Heating Help

Can't Heat 4th Floor Apartments in Front

Hi everyone,

We manage a 4 story brick building with 4 apartments per floor (2 in the back
and 2 in the front per floor). We have one pipe steam heat with oil fuel. The
boiler (see pics) is located near the back of the building so the mains that go
to the 2 stacks of apartments in the back are shorter than the mains that run
to the 2 stacks of apartments in the front of the building. The mains to the
back apartments are about 20-25 feet long after they exit the boiler room (the main
vents on the short mains probably are not working, but the back of the building
has no problems heating so we haven't touched them). The mains that go to the
front 2 apartments are about 55-60 feet long after they exit the boiler room.

We used to have an old heat timer that was probably out of calibration and the
building used to overheat (heat ran day and night). We have since installed the
MPC Platinum Panel by Heat Timer with an internet communication panel and space
sensors in each unit. The building runs cycles like the normal heat timer, but
it takes feedback from the space sensors and will not run a cycle if the
average temperature is above the set average. Our set average is 70 degrees
during the day and 67 degrees at night. The system works very well in mild
weather and usually works ok once the weather is consistently cold. However, if there is a sharp drop in outdoor temperature, we sometimes run into problems.

At 11:00 PM the night cycle starts and the boiler turns off and will not run
cycles until the average temperature in the building drops to 67 degrees. This
works very well on most days. It keeps the building cool at night for sleeping
weather. In the morning the heat timer runs a boost cycle (the cycle gets
longer the colder it is outside. It sometimes runs for 1.5 hours if very cold)
When the temperature drops from a day with a high of about 45 to 50 degrees to
the next day where the temperature is 20 to 30 degrees the two apartments in
the front of the building on the top floor do not heat up. They keep falling in
temperature and it is very difficult to get them to heat up (even with the heat in bypass for 2 hours). Additionally, the
front top floor apartments are always cooler than the rest of the building, but
usually within 3 to 4 degrees of the average.

What happens is that starting at 11:00 PM the boiler turns off for heat, the
pipes get cold, temperatures in the building fall. The front units are cooler
to begin with because the sun is on the back side of the building during the
day. Since the boiler stays off for a longer time at night now, the pipes get
cold. In the morning the boiler starts up, and temperatures climb in most of
the units with the boost period, but temperatures barely rise in the top floor
front units. (They then start to fall throughout the day) The other units in
the front usually heat up with the back ones, but are still a bit cooler than the back ones.

We tried to solve this problem by doing a few things:


1. We made sure that all supply valves were open and replaced some radiator
vents in the units. (All radiators are able to heat up and hold steam)

2.We installed new main vents at the end of each run to the front of the
building (see pics of old vents and new vents).

3. We even installed master vents on the top floor to help get the air out and
the steam up the apartments faster. (see pics).

What else can we do to get these apartments to heat up along with the rest of
the building? Any help is appreciated.


Hopefully that wasn't too long, I just wanted to provide as much pertinent
information as possible. If you need any more information, please let me know.


Thanks,

Jeremy


 

Can you confirm

a couple of assumptions I might make?  That is -- the third floor front apartments heat OK, just like the rest of the building?  And the front apartments are all on the same riser, or same two risers?  If they there are two risers (one for each stack) for the front apartments, do both top floor front apartments behave the same way?

You see... what I'm looking for is what, if anything, is common between the two top floor front apartments, which is not shared by the rest of the apartments.

For some reason -- and we'll figure it out, I'm sure -- the two top floor front apartments aren't getting steam from a cold start.  Logically something is in common for those two, shared by nothing else -- and that something is preventing steam from getting there under certain conditions.  It is most likely that somewhere in the piping there is a sag or loop which is allowing water to collect, and keeping steam from getting by... but there are other possibilities.

insulation and resistance

Jeremy --

I'd like you to have a look at my Excel venting sheet (link in signature) .. it's not enough to simply vent all the rads .. you are going to need to provide some resistance to the back apts to equally send all the steam to all places in "roughly the same time" ... in my system, I have a pair of mains (insulated) and it takes roughly 4minutes extra to go an extra 10ft of main length (2in pipe). since your mains are so drastically different, that could be 20minutes just to get to end of the front mains. all the while, the back rads are busy on their way to satisfying avg building temp.

using the excel sheet .. i would play with the minutes to vent column (which really translates to resistance) and i would raise the minutes to vent higher for the back mains and lowest runs ... the lowest minutes to vent values should be your highest front locations. please note that if you set all minutes to vent to be the same value, this should equate to all rads getting heat at the same time. additionally, since you have added additional venting, i think you should use each "vented segment" as a different piece of equipment in the first column.

and just a note, although it does look pretty good from your pictures .. try to insulate everything you have access to using 1" fiberglass pipe insulation.

let us know.

Response to Jamie

Jamie,

The third floor front apartments heat ok. They aren't as hot as the back, but
only a degree or two below the average (not 10 degrees or more below the
average like the top floor front apartments when the weather changes). (See
temperature data and boiler cycle time data in pictures below)

Apt 7, 8 are back 3rd floor.

Apt. 9,10 are front 3rd floor.

Apt. 11,12 are back 4th floor (top floor)

Apt. 12A, 14 are front 4th floor (the top floor hard to heat apts)


If you look at the data from 12-15 to 12-16, the top front apts (12A and 14)
fall in temperature over night between 12-15 and 12-16, they come up a bit in temperature in
the morning with the boost, but starting at 8AM or 9AM on the 16th they start
to drop again. This always happens when the temperature drops quickly. You'll
see that on the 16th, the boiler ran throughout the day, but the temperatures
in apts 12A and 14 keep dropping. Once they drop more than 7 degrees below the
average space temperature they are thrown out of the equation by the heat timer
(this works well if someone leaves a window open or likes to cook often, but
not when you can't heat the cold apts)

There are a few risers and radiators in the front units. I attached a diagram
to show where they are. The first riser along the very long main to the front
of the building is located between the kitchen and one of the bedrooms. The
farthest riser is in between the bedroom and livingroom. The farthest riser is
where we put the master vent.

The front units are mirror images that share the same livingroom and hallway
wall. Neither of the top front units share the same riser or even the same
main. What they have in common is that they are the farthest apartments piping
wise from the boiler. All apartments below them have exposed risers coming up
through the apartments that are not insulated, but the top floor does not have
risers in the rooms because the radiators connect directly in at the top of the
riser. Would that make a big difference? Also, parts of the mains may be
missing insulation once they are in the walls after the boiler room. I would
need to check to verify though.

The radiators in apt. #12A and #14 are all able to get hot. I put the boiler in
bypass mode for about 2.5 hours today and the radiators got hot all the way
across. However, I kept the building on so long that the back apartments were
near 80 degrees and the hard to heat apartments were still only mid to high
60's.

Any other information you need please ask. Thanks for the help thus far.

-Jeremy

Do the

different floors have different risers, or do all the apartments in a stack (say, 12A and the apartments under it) all share the same risers?

I'm beginning to think that, curiously, a combination of insulation, or the lack of it, and venting may be what we are looking at -- but I want to sleep on it.

The stacks,

like apt. 12A and apartments underneath, share the same risers.

response to jpf321

jpf321,

Thanks for your response. Are you
suggesting that I try to slow the venting in the back of the building so the
front has more time for the steam to get to the risers? If so, how would you
suggest I do this? (buy radiator vents with a slower venting rate or something
else?) We are renovating an apartment in the back of the building so I have
access to some of the mains that go to the back of the building. One back main
has an area where there used to be a main vent, but is now plugged (that should
slow down the steam) and the other main has a vent that looks like the old main
vent that used to be in the front of my building (see pictures from original
post). That vent seems to be painted over so it probably doesn't work anyway.

I guess I’ve been trying to speed up
the front, rather than slow down the back. That way the boiler will run for
less time. I will take a close look at that excel sheet tomorrow with fresh
eyes. I will probably have some more questions for you though.

All parts of the main that I have
access to are insulated (I’ll double check to make sure). There may be some
areas along the main that are not insulated. If I can access them, I will
surely add insulation. Should I open up areas to insulate if I find that some
portions of the pipe are not insulated? Would this make a dramatic difference?
If yes, then I would consider opening some walls.


Thanks,
Jeremy

putting the 16 unit system in good order

if it were my newly acquired building, i would :
1. install a vaporstat, and 0-16 oz. gauge, setting the pressure at 8 oz. max. 
2.wrap insulation strips around any exposed mains any where between boiler and radiator.
3. buy and install at least 2 gorton#2's [on antlers]  for each dry return, or end of counter-flow main. check that steam is getting to all main pipe ends in the basement at the same time.
4. clean the sight-glass, and verify that the water is clean, and pure.
5.temporarily turn off the night setback during the investigatory period, as well as any auto/over-fill setup. i would have a wire with 2 alligator clips so i could short the control system, making the boiler run constantly for the tests.
6. after getting the steam at correct low pressure to the furthest risers in the basement simultaneously, i would move to the top floor, and see that steam is arriving at the top floor radiator shut-off valves simultaneously. check the intermediate floors after the top. the goal is to enable steam to arrive at all radiators on all floors virtually simultaneously. any big radiator vents could be saved for any slow top radiators. in the lost art of steam heating, there is mention made of steam travelling through pipes at a speed of 60 mph, so it should not take to long for it to get to the stop valves of any radiator. disregard any measurement of room temperature until you have the steam moving quickly.
7.once the steam is in the right places as quickly as possible, then it is time to start making whatever control system you have turn the boiler off and on at the right time. it may not even have the right control, for the purpose, but you won't know that until you have the steam working properly.
in the next few weeks i would watch the waterline for loss of water, or getting too dirty, and act accordingly.--nbc

A few Questions and Responses

Nicholas Bonham-Carter,

Thanks for the suggestions. I have a few questions for you or anyone that can
answer:

1. We have a vaporstat already. Not sure if it is set correctly. Please take a
look at the picture and advise on where to set MAIN and DIFF. on the gauge if
it should be different from where it is now.

2. I'll take a look at what mains I can see tomorrow and plan on adding
insulation to any accessible section that isn't covered. Should insulation go
around the header as well?

3. Right now we only have one main vent at the end of each long main to the
front. We have since sealed them in the wall, but left a little panel for
access. If needed, we could get in there and install more vents. I attached a
picture of one of the main vents we installed. I believe it is a Hoffman #76. I
know you recommended the Gorton #2, but is the one we have ok as well?

The master vent at the top of the stack is a Hoffman#75.

venting choices

the hoffman vents are quite a bit more expensive, and less capacious than the gorton #2's, which offer "more bang for the buck". as you can never have too much venting, use those generously. with the high velocity of steam at low pressures, there should be no difference in arrival times for front and back, if the air can get out equally quickly.
i agree with the suggested vaporstat settings, as you need  some residual steam in the lines as the boiler re-fires, in order to avoid the sucking in of air. naturally, when the heat-timer is satisfied, the vents will open to enable the subsequent vacuum to be relieved, and prevent possible rise of the boiler water up into the wet returns.
just make sure that the hoffman vents are not the "75/76-H" model which has a vacuum check valve in it. how many mains are there? if they are more than 50 ft. long i would put 2 gortons on each, and can be mixed with the hoffmans. the hoffmans could also be moved to the shorter mains, and the gortons put on the longer ones. the point is use plenty of vents!--nbc

Question about Hoffman 75 or 76-H Vents

One of the main vents I have is Hoffman No 76 Main Vent Vacuum Valve (pictured below). The other is Hoffman 75 Main Vent Air Valve (pictured below). So is the 76 the wrong type to have? I have no idea why there are two different kinds installed. May have been a mistake.

I'm going to post some main measurements in my next post. From measuring so far I think the main to the front could be up to 60 or 70 feet long after the first take off from the boiler header.

running out ...but ..

a quick response before i head out for the evening.

have a go at the excel sheet .. and set all your times to a constant to start .. perhaps 5mins. that is, your desire to vent the entire system (including having hot rads) within 5mins .. this is not going to be the real-life effect so don't get too excited .. but the theoretical model .. then have a look at the various "CFM to vent" needs for the various system elements.

please remember that steam is going to travel the path of least resistance .... it you want it to head towards the front first (or in a balanced manner) then you should probably work to slow the rear .. and yes it may mean putting smaller vents in the rear... the excel sheet has recommendations for both Gorton rad vents and Hoffman 1A adjustable vents. my email address is in the sheet, you can contact me directly if you like.

i would not open any walls to insulate until such time as we have worked on a better balance. to begin with, it might be useful to time the system as it stands currently .. i did see pipes in your pictures that were not insulated .. (black pipes shown in rooms with rads) .. those look like they are accessible

time until boiler header get steam_____
time until each main end gets steam_______
time until each rad get steam______

this will provide you a baseline and allow you/us to understand improvements as they are made.

Jeremy, these guys are right

when they say to speed up the front main rather than slow the rear one.

Measure the length and diameter of both mains and tell us what vents you now have on them. This will give us a starting point. You may need something like what you see in the picture below.

take steamhead's info over mine

I'm an enthusiastic newbie .. i try to do the right things .. but if steamhead says to speed up front rather than slow rear .. let's work on getting that done. Have a look at this article, written by another "authority" and give it some thought as well: [url=http://www.heatinghelp.com/article/11/Hot-Tech-Tips/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell]http://www.heatinghelp.com/article/11/Hot-Tech-Tips/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell

after thinking some about steamhead's comment .. it's not so far off of mine .. the general answer is to balance the system to ensure that steam arrives everywhere pretty much simultaneously .. I think that in the end, it will mean a "slower" back (relative to front)...however, since you have the back setup already .. lets speed the front (relative to back) from the current back setup .. rather than change the back to come down to the current front setup...same premise .. different starting point...as Einstein stated it's all about relativity. I guess I just learned a valuable lesson once again .. always look towards speeding up rather than slowing down relatively speaking...again, generally, you want to make all paths equally attractive as paths of least/equal resistance...and let's start with the current back and speed from there.

get back to us with the main lengths and diameters as steamhead suggests.

i did have other question out of my curiosity .. in the floorplan you provided, where it the t-stat located? do all apts have the same floorplan? are the t-stats located in the same place in each apt?

jpf321:

Thanks for the article. It has some good information. I
think I'll probably need more main venting. In another post I listed the type
of main vents we have in the building and asked if anyone thought I should
change them, add to them, etc.

I'll get you the guys the main lengths and diameters ASAP.

 To answer your questions: All front apartments have the same floor plans.
They are all two bedroom apartments (2 per floor  and mirror images of each other). The back of the building contains
one bedroom apartments. When you say, "are the t-stats located in the same
place in each apt" is t-stat, thermostat?


-Jeremy

Steamhead:

I've been reading Dan Holohan's books. That's when I realized about trying to speed the front up rather than throttle back the rear units. However, what I have done so far doesn't seem to have been enough.

I will measure the length and diameter of the mains tomorrow. Should I take the measurements of diameter from the area closest to the main vents? I'm not sure if the main diameter gets smaller as it gets further from the boiler room. The diameter of the mains in the boiler room look larger than near the main vents at the end of the run.

I included a close up picture above of one of the main vents that we installed in the front of the building. I'll put it in here as well. Its currently inside the wall, so I did my best to read it off of the picture I took. It says No. 76 Main Vent Vacuum Valve. ITT McDonnell & Miller. Under their website it's listed under Hoffman Specialty Model 76 under vents then steam: [url=http://www.hoffmanspecialty.com/HS-General-Catalog.asp]http://www.hoffmanspecialty.com/HS-General-Catalog.asp

The master vent at the top of the stack is Hoffman #75 Main Vent Air Valve.

Are the vents currently installed the right kind? Do I need more venting?

Thanks for all of the help.

measure are precisely as possible

yes t-stat = thermostat and I guess what I meant to say was temp sensor since I realize they are connected remotely.

measure as precisely and with as much detail as possible .. the goal is to get a proper figure for the air which is within the system. measure from the header of the boiler to the end .. you already mentioned mains towards back at about 25ft and towards front @ 50ft ... but try as best you can to determine the diameters and lengths ..
for example ..
front main .. header + 35ft @ 2in + 15ft @ 1-1/2in + 10ft @ 1-1/4in
front main current vents: 1piece hoffman 76 at far end and ????
do the same for rear main.
you are really trying to paint as detailed a picture as possible of the system piping short of actually drawing it out. feel free to post pictures liberally as well.

(this chart may help you to measure AROUND (outside circumference - column 3) the pipe and then determine pipe-size (inner diameter - column 1))

thanks for the chart and info.

The space sensors in the units are in between the kitchen and the hallway on
the inside hallway wall about chest high. They aren't thermostats though. The
heat-timer controls the heat cycles. If you are unfamiliar with its operation,
here is how it works:

There is an outdoor temperature sensor placed outside on a north facing wall
(to avoid direct sunlight) and an indoor system temperature sensor that is
placed on either the furthest radiator riser or one of the dry returns (it's
usually hard to wire it to the furthest radiator). Regardless, you set the
indoor system sensor at whatever temperature the system sensor reads when the
last radiator in the system or hardest to heat radiator begins to get warm. In
my building that is 160 degrees (although for some reason heat does not seem to
be reaching the last radiator now). The heat timer then runs the burner in a
precycle up to 160 degrees (in my case the boiler runs for about 12 to 16
minutes to get up to a system temperature of 160, it then runs a cycle, see
below).

At that point it is assumed that heat is established (heat has traveled through
all mains and up all risers and has arrived at all radiators) Then the heat
timer runs a 60 minute cycle with an on and off period (example 10 minutes on
50 minutes off). It stays on for longer amounts of time depending on how cold
it is. You need to set day and night temperature cut offs and heat adjustment
(letter A to P: the higher the letter, the longer the cycle). During the day,
the heat timer will not let the burner turn on if it is above the cut off
(default is 55 degrees). If it is 40 degrees outside it calculates a formula
(55 degree cut off minus 40 degrees outside = 15 degrees). If you are set on
letter D heat adjustment, there is a chart that determines that 15 means run
the boiler with a 4 minute cycle. If it is 30 degrees outside it would take 55
degree cut off minus 30 degrees = 25. According to the chart it will run for 9
minutes. It is an exponential scale.

If that paragraph above seemed kind of complicated the whole point is that you
match the heat loss of the building with the increased heat cycle times as it
gets colder (the more heat loss the more heat you need) You change the heat
adjustment until the cycle time seems comfortable. My system is upgraded so I
can go on to the heat timer website to control my system remotely, view
temperature data, cycle times, etc. Check it out: htcontrols.com or check out
the main website at heat-timer.com

The internet control management system is very convenient. It can even send
text messages or e-mails if your burner locks out, if heat does not establish
after 1 hour, if the average temperature drops below a certain set amount, etc.
There is a lot of additional equipment you can attach to it. If you have any
questions, let me know.

But anyway, the space sensors act only as a set back to make sure the building
does not overheat, they do not call for heat.

I'm no expert,

but your vapourstat does not seem to be set properly. It looks like you have 14 oz cutout, but virtually no differential. Do you have problems with the boiler short cycling? You need some differential between cut in and cut out pressures. It appears to be a subtractive vapourstat, so you might try 14 cutout, and 7 differential (which would have your system working between 7 and 14 oz of pressure - this might be higher than you need)

If somebody else suggests different numbers, use them - I'm no pro.
I'm pretty sure no differential is wrong so since nobody commented on it I thought I would.

Assuming your mains are well vented, I'd suggest bigger vents on the radiators in the cold rooms. This should allow them to fill with steam faster. The conventional wisdom is that vent size should depend on radiator size - probably a good rule of thumb, assuming that the radiators were properly sized for the heat loss of the room. But if a room is still cold, then more venting can help if the radiators never fill with steam during normal operation..

Oh good!

That's one of the older vaporstats -- hang on to it.  They are very very reliable.  You do have it set higher than need be -- try setting the main at 12, and the differential -- which is subtractive -- at 8.  That may turn out to be a tad low, but it's a place to start.

The general buzz also seems right as far as it goes; try getting more venting on the front mains and risers (I'd go for Gorton #2s, both for the main vents and the top of riser vents).  The Hoffman 76 is a very very reliable vent -- but it isn't all that fast, particularly compared to the Gorton #2.  This may help speed things up in front.

I am still concerned, though, that there is a bit more to it, and I think I would be inclined to go to some lengths to make sure that the front mains are well insulated.  I would also be inclined to insulate the risers, if you can get at them.  It is surprising how long it can take steam to make its way through a cold pipe, good venting or no.

David K and Jamie,

I thought something might be wrong with the vaporstat
settings. Although, we are getting steam in the building without short
cycling... Can someone explain how you come up with the vaporstat settings? I
get that you need high pressure to low pressure in order for the vents to open
and close, but how do you know where to set it and what to change it to if it's
not right.

Jamie, what if we kept the Hoffman 76 and added additional Gorton #2 as well on
the main? That should work, right? Although I guess we would have to do some
additional piping. Is it bad to mix main vents?

UPDATE: It's still well below freezing today and the third floor FRONT of the
building, while still getting heat, is about 5 degrees below average. Basically
the front of the building is a bit colder than the back, but the top floor
front is A LOT worse. It doesn't help with balancing that the sun shines on the
back of the building all day either and not on the front.

Pressure settings and vents

First off, let me reiterate -- that vaporstat you have is one of the old mercury ones.  Hang on to it.  Don't let anyone talk you out of it.  It is worth its weight in gold, and then some!  It is much much better than the new ones.  There is only one better pressure controller available, and it's rather expensive -- Gerry Gill makes it.

The optimum setting for pressure is something of a guessing game, once you get in the ballpark.  The idea is to have enough pressure to get the steam reliably to the end of the system -- and 8  to 10 ounces should do that -- and no more.  On some buildings (and yours may be one) it may be necessary to go as high as 14 to 16 ounces on the cut out (for reference, the Empire State Building runs with a 24 ounce cut out!).  The differential controls the length of time between when the burner cuts off and when it cuts back on again.  You don't want it too short, but you don't want it longer than a minute or two, either.  You sort of have to feel your way on it.

On the vents: no reason not to keep the 76.  It's a fine vent, and just about bullet proof.  The best thing to do is to add the Gorton #2 along side it, and just about any combination of Ts and nipples and elbows which will fit your space will do it, so long as the vents sit upright and are above the main (no loops or dips in the piping permitted!).  Sometimes the odd union in between vents, or between the vent piping and the main, can make life a lot easier.  You'll hear such arrangements referred to here on the Wall as "antlers" or "menorahs" --  for obvious reasons.

The problem child apartments would be on the shady side, and on the top floor.  That is the worst possible heat loss in the building!

We'll get there.  No fear.  Just keep the tenants happy... !

Jamie,

Thanks for the info. Is either the menorah or antler setup better than the other? Should either of them be pitched to allow any condensation to escape if it gets up there, or just keep the arrangement level?

It really is tough that the front is shady and the furthest from the boiler. I really need to speed up the mains.

pressure discussion

Jeremy --

I asked similar questions about how to determine optimum pressure recently .. have a read through this thread: http://www.heatinghelp.com/forum-thread/128681/Understanding-working-steam-pressure

FYI, I'm still not sure if I understand how to obtain optimimum pressure, however last night I turned my vaporstat down to 3oz with a diff of "bottom scale" .. in my case, due to ignition delay, this differential allows the pressure to drop a few oz. before the fire starts up again. I had been running at 8oz and 4oz .. but I keep dropping it. The way I understand it, as soon as the vents close, no more steam can enter anyway, so why build any pressure at all, I'm trying to trigger cut-out as soon as I begin to sense pressure. And yes, all my rad vents are closed due to steam at 3oz. My longest run is 55ft @ 2in + 20ft @ 1-1/4 into a 27sqft EDR Burhnam Radiant.

BTW, my vaporstat was much more precise at 8oz than at these low pressures .. a setting of 3oz really doesn't trigger until 4.5/5oz. and the bottom scale diff actually causes the needle to be jumped below 0oz.

What I'm particularly please at however is that last night when it was at 16degF with 10mph winds .. my boiler shut-down on pressure but did not start up again (t-stat was satisfied) and it was the shortest cycle I had so far (41mins) with no recycle based on pressure .. but perhaps I just got luck on that cycle. Anyway I ramble.

Main Length and Pipe Diameter

One picture below diagrams how the main runs from the boiler room, underneath one of the front stack of apartments, to each take off riser.

I included as many pictures as I could of the mains so you can follow them in the pictures. The pictures are ordered from near boiler to the end of the main (pics ends at the main vent). I could not get pictures of the middle of the run because the pipes are in the wall. The bad news is that the middle of the run is not insulated. The pipe sits uninsulated in a small space in the wall. Should we open walls to insulate or only as a last resort if more venting does not improve the situation?

It was a bit difficult to get the diameter of the pipes, but my measurements should be pretty close. I start my measurement of one of the mains to the front of the building from the first take off upward from the boiler. Is that the best place to start?

11 ft. @ 4.5 inch outside diameter then 70 ft @ 3.5 inch outside diameter. At the end of the run is a Hoffman #75 Main Vent Air Valve. At the end of the other main run to front (similar in length is a Hoffman #76 Main Vent Vacuum Valve).

I also included pics of the main vents again here. Let me know what this tells you. Any advice is appreciated.

Thanks,
Jeremy

Here are my vent calculations

Since you measured outside diameter, the 4.5" is actually 4" inside diameter and the 3.5" is actually 3".

11' of 4" at 0.9 cubic feet per running foot is 0.99 cubic feet.

70' of 3" at 0.5 cubic feet per running foot is 3.5 cubic feet. Adding the two gives us 4.49 cubic feet of air.

We want to vent that main in about a minute at an ounce of pressure if we can. So:

According to Gerry and Steve,  one Gorton #2 will vent 1.1 cubic feet at one ounce of pressure. Dividing 4.49 by 1.1 = 4.08.

So you should start with four Gorton #2 vents at the very end of the main. You can get away with four of these vents on a 3/4" riser.

The branch lines could use much smaller vents. If you vent the risers near the top, you may not even need branch line vents.

Question About Additional Main Vents

What is the best way to add the additional main vents? Can I
put them in series on an antler or menorah in the same spot I have my current
main vent? Or is another location more ideal? Which is better: an antler or menorah
set up (or do they work equally well)?

My mains take a 90 degree turn go about 2 feet then take an additional 90
degree turn where the main vent is 6 inches up on a pipe. The main then
continues and eventually goes down into a wet return. (see pics)

Thanks for the help.

-Jeremy

Antler or menorah

will work, as long as all the pipes are pitched so water cannot collect in them. 

See my just previous reply to you, but also

You surely do need more main venting.  The good news is that it looks as though you have enough space to put a nice antler on; use the spread sheet to figure how many Gorton #2s you need on each main, and then start putting things together!  As I said in that previous post, you can keep the 75 and the 76; they won't hurt anything.

The bad news is... get the vents on, and see what happens.  But I'm going to bet that you are going to want to open up that wall... and insulate those mains... don't get out the SawZAll until you try the extra venting, though.

looks like...

using the spreadsheet... it looks like 70ft @ 3.5" + 11ft @ 5"(being liberal) requires 2.147cfm @ 3minutes to vent...this equates to 2pcs of Gorton #2.

it would require 5pcs of hoffman #75 or close to 6pcs of hoffman #76 to sufficently vent.

you can see now jeremy how much more venting power the Gorton's have. if you still have questions about how to use the spreadsheet, please contact me directly.

Going Forward

I plan on adjusting the vaporstat and increasing the venting to start.

It seems that most people on here prefer the Gorton #2 vs. Hoffman 75 or 76 because the Gorton#2 vents faster. Are there any disadvantages to the Gorton #2 vs the Hoffman 75 or 76. Jamie, you commented that the Hoffman 76 was a very very reliable vent. Is the Gorton #2 the same caliber? What are the pros and cons of each?

I am not as concerned with the cost of the vent as much as reliability and effectiveness. This is a 16 unit tenanted apartment building and I need to make sure everyone has acceptable heat.

The main vents only have a small access panel to allow me to get to them. They are otherwise walled off. I do not want to have to go back in there anytime soon after adding additional venting.

Is the advice to go with Gorton #2 vents for the mains still the same?

If the above does not help, then I guess I'll be opening some walls to insulate the pipes better. Thanks to everyone for the help.

-Jeremy

hoffman 76 vacuum vent

that 76 has a disk on the top, which can be removed when the cage is "unscrewed". it will not relieve the vacuum without the removal of the disk. the gortons are much more capacious, and if they are to be mounted in a hard to return to spot, add an extra one, to keep the escape air velocity down as low as possible. this avoids a buildup of debris in the vent. an antler and menorah of 3/4" pipe are equally effective, and i like to put a ball vave under each vent, so as to make later changeouts safer, and easier.
reliability of vents i would think is related to obstruction, from dirt, and i have had good luck with both hoffman, and gorton, as long as they are protected from water-hamer.
you can wait until the system is running perfectly, venting-wise, before insulating the hidden risers. if they are protected in the interior walls, they are not so critical, as if they were out in the open, or in an outside wall.--nbc

without knowing the pros/cons...

I think Steamhead's signature picture speaks for itself.

You may also want to look at Rod's post in the thread about my system regarding "Main Vents".. it also includes drawings about how to mount things .. http://www.heatinghelp.com/forum-thread/128365/Looking-for-a-Steam-Pro-for-site-survey-visit#p1179896

TRV Video ...

Jeremy -- I just saw this video for the first time .. watch the first 1-2mins .. maybe it will give you something to think about ..

cool video!!

these may be the solution, HOWEVER the system must still be balanced, as well as possible, as later balancing can be trickier, with the valves installed.
an analogy would be if your car brakes are dragging, however instead of fixing them, you put in a more powerful engine to overcome the drag!
remember that these valves cannot call for heat, or fire the boiler, as they are more like the new antilock brakes which will slow down that one slipping wheel on the ice
i suspect when you have finally worked the bugs out of the system, the radiators will more simultaneous.--nbc

day cycle..not products

actually .. i was referring to looking specifically at the day cycle part of the video .. i wasn't at all trying to suggest that TRVs were a solution in this case. Since Jeremy has mentioned that the rear apts are sunnyside and the front apts are shady. 

Piping

Check the boiler piping. It is under sized.

UPDATE:

We have made a few adjustments to our system that seem to have helped. When we called in a heating company, they told us our boiler was underfired and they upped the nozzle size and made a few other corrections. They also said we did not have the low-high-low fire modulation hooked up correctly. They attached our vaporstat to control the modulation of the fire and put in a pressuretrol to control the operating pressure. That seemed to help a bit, but I decided to follow a lot of the suggestions on this board as well.

I bought some Gorton #2 main vents and placed 2 on each long main to the front of the building along with 1 hoffman #75 that we already had. Each long main to the front of the building now has 2 Gorton #2’s and 1 Hoffman #75. The back of the building (with much shorter mains) currently has no main vents, but the building seems much closer to being balanced. The top floor front apartments could be a bitwarmer (compared to the other front apartments), but they no longer drop to the low 60’s.

My Questions:

1. If I add main vents to the back mains, will it take away steam from the front mains?

2. Steamhead, you recommended 4 Gorton #2’s at the end of the front mains and mentioned that we can vent the main in about a minute at an ounce of pressure. How do we do that if the pressuretrol is set to cut in at .5 PSI and out at 1.5 PSI? Will adding more Gorton #2’s with the current setup still be beneficial? I’m trying to understand why people talk about venting at one ounce of pressure when most systems do not even run that low. Can someone explain this to me? Should I still add the same number of Gorton #2’s with my current pressure settings?

3.   We created a menorah setup as shown in the pictures below. It was difficult to obtain pitch on one side of the menorah. If the pipe is about level will that be ok? If it were slightly back pitched would the vent not work at all? It doesn’t seem like that much water could puddle up in a ¾ inch pipe even if it was only level.

Thanks for the help.

When you say

"each long main to the front of the building",

does this mean you have two sets of the following........

"11' of 4" at 0.9 cubic feet per running foot is 0.99 cubic feet.

70' of 3" at 0.5 cubic feet per running foot is 3.5 cubic feet. Adding the two gives us 4.49 cubic feet of air. "

what is the pressure of your system?

i think you need a lot  more venting of the mains. also, you need a good low-pressure  gauge, as i mentioned several weeks ago.
remember that the main vents are only controlling the escape of air in the system, and that with them you can only control the steam arrival at the risers. if the mains are massively vented, then my view is that the arrival of steam at all the risers is almost instantaneous, [at 88 FPS]. i would put the same several gorton #2's on each return. you can never have too many vents!
find out how to jumper the starting control for the boiler, so that you can make some tests without running upstairs, to enter some settings into the heat-timer. find out if steam is arriving simultaneously, based on the radiator temperature.
you might want to use a good thermostat, instead of the heat-timer, for a while to get the system sorted out, and see if the heat-timer might be part of the problem.--nbc

Steamhead:

The first 11 feet of 4" pipe is shared and then the main splits into two different branches that head to the front of the building. Each branch is 3" pipe and about 70 feet long each.

I think the thing confusing me is the venting capacity chart from Balancing Steam Systems by Gerry Gill and Steve Pajek. It seems that at higher pressure, air is vented more quickly. Is that right? If so, why do we use the one ounce scale? Maybe I'm just missing something.

OK, the first part is shared

You might be able to get away with adding just one Gorton #2 to each 70-foot run, leaving the existing Gortons and the Hoffman #75 vents in place.

As to the pressure, jpf is right. A steam system always starts at zero pressure, so you need to vent at as low a pressure as possible.

venting...

please remember that vents are always open until they get steam to them and that pressure doesn't increase until vents are closed .. therefore a system will always, or almost always, be at 0oz/in at startup and will be at 1oz long before 8oz and will only get to 8oz once vents have already done their job and are now closed in the presence of steam. hope this helps. 

After reading all of the comments,

it sounds like it may be best to buy 2 additional Gorton #2s for each long main so I end up with a total of 4 Gorton #2's on each long main to the front of the building (or at the very least buy 1 additional Gorton #2 for each long main to the front). That way I will have the maximum amount of venting on the menorahs set up in the front.

My plan would be to re-use the Hoffman #75's on the shorter back of the building mains that currently have no main vents. Does this sound like a good idea, or would adding more venting in the back take away from the front? It would be much easier if I could just go in and out of apartments anytime I wanted, but since there are tenants in each unit, it's not so easy to test out ideas, time the steam, and try different set-ups, etc.

The back of building, despite having no main vents, seems to heat fine... Occasionally the top floors will be a bit cooler than the lower floors, but steam doesn't seem to have a problem reaching any of the back apartments no matter what floor.

Thanks for all of the advice and information.

maximize and measure

maximize the venting to as close to open pipe as possible .. aren't you in NYC? i'd love to stop by and poke around .. contact me directly .. perhaps I can also loan you my temp dataloggers for some measuring tests ..

anyway .. maximize all venting as much as possible to take the timing for steam arrival to vent point out of the equation ..

assuming they are in good working order, the hoffmans on the back would be fine .. i think that it was in this thread that steamhead taught me not to de-vent/limit  an area but rather to increase venting on the weak area. how's your pipe insulation? i've gotten to know the guys at Allstate Insulation in Maspeth ... they are very helpful.

JPF

I'm actually located in Boston, but if you ever are in my neck of the woods, let me know.

I did run the open pipe test with 3/4 inch pipe and it reduced the time it takes steam to arrive at the end of the main by a few minutes compared to when I just had one Hoffman #75. Like I said before though, it's hard to run tests because I have to go in and out of tenants' apartments multiple times. They've been nice about it so far, but I don't want to push my luck. It's also tough because to test accurately it is usually best to do it from a cold start, no? Then I have to turn the boiler off for a few hours. If I do it from a warm start then it will naturally not take as long for steam to reach the end of the main because the pipes are already warm.

We purchased some 1 inch thick fiberglass insulation for areas where the mains are not buried in the walls, but haven't put it on any pipes yet. The header isn't insulated, so I figure that should help once covered. I wanted to see how much the Gorton #2's helped first before adding insulation.

The two 70 foot long mains that go to the front of the building are not insulated the whole way. The parts that I can see when I poke my head inside the wall are not covered. No one on the board seemed to indicate that it would be worth it to open up the walls just to insulate the pipes inside. Either way, It would be pretty disruptive to the tenants. Unless it would make a pretty big difference, I'll just leave the pipes in the wall alone. After adding a couple more Gorton #2's I'll start on the insulation in accessible areas and let you know how it helps.

cold start vs. warm start ...

i would do my testing using the more common start .. all my testing is done with my boiler water at lest 170dFahr since I have an aquastat on there for my DHW and I will never be below there.

yes things will certainly change depending on temp of boiler and pipes .. but you can never really get the same start conditions every time.

as I mentioned here the other day, warm pipes will increase speed to main end. if your system will likely never be off for longer than X time, don't test with it being off for longer.

open pipe test

when you do that test again, can you hear any noises indicating a sag of water-filled pie restricting the flow- something like panting or gurgling?
don't forget how important low pressure [8 ounces is ideal] is in the speed of steam arrival!---nbc

Pressure is set to cut in at .5 PSI and out at 1.5 PSI

When I did the open pipe test a few weeks ago I listened for sounds. About a minute or two before the end of the main got hot I heard water rushing through, but I think it was from the condensing process. There was no banging or water hammer sounds. It did sound like the air would come out in spurts at first. A rush of air and then nothing, then a more air, until eventually the air was coming out more constantly. Does that sound right?

When I did the open pipe test in the back of the building, it seemed like the steam rushed out faster with less spurts of air then no air, but I last tested that out several weeks ago, so I might not be remembering exactly right, but that was my general impression. I also heard the water sounds in the back but I think it was just condensate flowing towards the wet return like in the front of the building.

Last time I listened to the main vents (from the front of the building), they began venting air about 5 minutes after I started the boiler. With one Hoffman #75 it took about 14.5 to 15 minutes for the end of the main to get warm (from the start of turning the boiler on from a cold start). With an open 3/4 inch pipe it took about 11 to 12 minutes to get warm. At the most it seems like I can get the steam to the end of the main 3 to 4 minutes faster with maximum venting. Does that make sense it would still take that long (11 minutes) with an open pipe?

Cut In ...

With an 8 oz cut out, what would you recommend for the cut in?  I'm currently operating my apt building (4 story/4 units) at 12oz/4oz.

just a sugestion

you may have wrong size nozzel or partically blocked nozzel. i have had service calls were that was the problem.(in buildings and bakery ovens)   

About the Nozzle

That's a good thought. A few weeks ago the heating company came by and replaced the nozzle. It was undersized before and seemed to be set up incorrectly. The observation glass was all sooty before too. Now it is crystal clear and has been for a few weeks. I have a heating company coming back to take a look at the system and install a new low pressure gauge. We have a Weil McLain Model 80 Boiler with 8 sections. I think they wrote on the card that the new nozzle size is 4.25 (the old one was 3.75). I really have no idea what nozzle size is correct. I'm relying on them to tell me what's right.

nozzle size

the W-M website should give the info on nozzle sizes for various sizes of their boilers.--nbc

the load is important here for nozzle size

The old nozzle may have been put in to fire the boiler to match the load. In increasing the nozzle the boiler may now be over fired for the system. Was the system working before the nozzle was " improved" ?

The system:

The system produced heat, but not well to the top floor front units. The heating technician likened the smaller nozzle to "trying to boil water with a candle" or something like that. It's still not perfect; we still have days where the temperature of the top floor front units drops lower than the rest of the building, but it seems to have been better. It could also be that one of the service technicians who was here before changed the nozzle and it was wrong. The observation glass was all sooty so something was wrong with the way the burner was firing. I don't know if it was the nozzle size, but the head of the service department who just installed a bigger nozzle said we needed it.

What would happen if the system were overfired? How can I check?

I still need to add a few more Gorton #2's to the front of the building, as everyone has suggested. I went to pick a couple up at a local supply house, but the 2 they had in stock did not pass the blow test. I'm waiting for the next shipment.

how badly did they fail?

how badly did they fail the blow test .. i'm pretty sure that humans can blow at relatively high pressure .. much higher than 1.5psi

i have a gorton that fails blowtest but very slightly .. that is when i blow really hard, the air seeps out .. but since i operate at 5oz .. it works just fine.

there was a post on here a while back about how hard someone can blow .. i'll have to try to find it.

Blow Test

No air at all came out when I blew into the pair of Gorton #2s. I had bought 4 good ones the week before and could blow through them as easily as an open pipe so I figured something was wrong with the pair I was about to buy and said I would come back when they got a new shipment.

Over sized or "right" sized nozzle

A larger nozzle may waste fuel and cause short cycling of the boiler. The soot can be cause by many things including burred shoulder on the nozzle and a burner that was never tuned. Also leaking ropes on the combustion chamber can cause lots of extra air which can affect flame shape. Often times over sized oil boilers are down fired to better match the actual load of the building. A survey of the system as a complete unit needs to be done to accurately tell what the system needs for steam. I just installed 5 Gorton #2's on a system and they all work well. Can vents be added before the radiators to get the risers (stacks) filled faster?

added after rereading post
I guess you are adding vents, go away for a few days and the whole train goes past. Do you have an EDR for the building?

Charlie

So the only way to know the correctly sized nozzle is to see how many radiators (and which type etc) and piping are connected to the system? The last time the heating company came by, the tech only spent some time in the boiler room before telling us the boiler was underfired and that adding a bigger nozzle would help. He didn't go into each apartment and see what was connected. Does that mean he probably made a guess or is there another way to know what size to add? If he just upped the size without good reason it would use more oil for no reason then, right?

Even after he changed the nozzle, we are still having an issue with the top front apts. I  already added 2 Gorton #2's in addition to the already present Hoffman #75 on each long main running to the front. I know it is still recommended that I add more vents, and I plan on doing that, but is there anything else that could be going on here?

We added "master vents" at the top of the furthest from the boiler riser right before the radiator in each top floor front apt. Check out the last picture of the first post in this thread to see what we did. That's a Hoffman #75 in the picture.

As always, any comments and advice are appreciated. Thanks.

I am thinking someone chose that nozzle for a reason

the reason could have been wrong but they had a reason. The load is one factor for nozzle size but the boiler and burner need to be kept with in certain parameters too. Jeremy can you do a radiator survey? Dans book E.D.R. will be able to give you the square footage of your radiators and then you add them up to check the boiler rating compared to the load. Often times symptoms are confused for causes with steam systems, actually with any heating system. Its like taking Advil for your sore shoulder and ignoring the fact you carry a 50 pound back pack off that shoulder for 10 hours a day. Some how that steam needs to get to the top and the rest of your building when you need it. It may be it never did well from day one due to poor layout of the piping. It may also be the other side is better insulated than it had been and this side is still not so the heat load has changed. A building may have be3en torn down or built near by that change the micro climate around your building from the day it was built. The question is simply how do we make what we have work.

The first step is to find out the connected load.

I think that the top floor front

was always harder to heat since my family acquired the building. Like you said, that doesn't mean it never heated well at some point though... I actually just ordered that book a couple of days ago. I will probably take me awhile to figure out the E.D.R because there are probably around 30 to 40 radiators in the building. Will that book show me everything I need to know?

Appropriate nozzle and firing rate

A simple way to check if the firing rate is in the ballpark is to check and see if the burner cycles on the vaporstat or the thermostat (or heat-timer). If during normal operation the vaporstat cycles constantly during a call for heat, then most likely the firing rate is too high for the installed EDR. On the other hand, if during a recovery from setback the burner fires constantly for a long period and never cycles the vaporstat at all, chances are that the nozzle is too small and you are underfired.
By spending a little time observing the vaporstat while the burner is in operation you can get a pretty good idea of how well the firing rate is matched to the installed EDR.

Edit: I just read your more recent post where you mentioned that the tech now set up the system with HI-Lo-Hi modulation. The above only applies to on-off control of the burner, not the new modulation setup.

 In the case of Hi-Lo-Hi modulation, you would ideally have the boiler fire at Hi until all radiators were hot and filled with steam. At this point you would start to build pressure, and the vaporstat would switch the burner over to low fire where it would remain, maintaining constant pressure for the rest of the heat-timer cycle. If this is what is happening, then your firing rates are set up just about right.

Was the nozzle changed before or after the modulation was set up?

Mike:

Thanks for the reply. Yeah, this thread is getting long, so it's easy to miss something. The nozzle was changed the same day the modulation was set up.

When the burner first turns on it goes into high fire to start. It stays there for either a few minutes after start up (haven't timed exactly how long). It then proceeds to go into low fire for a couple of minutes then back to high fire for about 15 to 30 seconds and
then back to low fire for a few minutes. It keeps doing this until the call for heat is over.

The operating pressuretrol is currently set to cut-in at .5 psi and cut-out at 1.5 psi. The vaporstat that controls the low-high-low modulation is set to 14 oz with a 1 oz differential (the differential is subtractive). I also posted about this set-up in the control section:

[url=http://www.heatinghelp.com/forum-thread/129384/Carlin-Burner-Question-about-Low-High-Low]http://www.heatinghelp.com/forum-thread/129384/Carlin-Burner-Question-about-Low-High-Low

The last comment I got was from Steamhead. He suggested having my tech rework the firing rates so the low fire is higher and leave the high fire the same. I am still a little confused on exactly how the vaporstat is controling the fire while the pressuretrol is controling things too. Can anyone break that down for me? Are my vaporstat settings correct?

Firing rate modulation

What Steamhead said is correct. Your Lo firing rate is just a little low and is inadequate to maintain the 14 oz pressure setting required by the vaporstat. In low fire, the pressure starts to drop and when it hits the threshold of setting minus differential, the vaporstat returns the burner to Hi fire until it reaches 14 oz again and the cycle repeats. In your present setup, the pressuretrol does nothing unless the pressure should rise to over 1.5 psi, so for all practical purposes it is now there just for a backup if the pressure should rise that high in low fire mode.
Your vaporstat differential seems a little low at 1 oz, which may be contributing to the Hi-Lo cycling. You might try increasing it to 2 or 3 oz, which should reduce the cycling. Another thing you can try is to reduce the vaporstat setting to 12 oz, which would not require as much of a Lo firing rate to maintain the lower pressure. You seem very close to the ideal settings, so just a little tweaking may possibly do the trick.

Fire Rate Modulation

Now I'm starting to understand how this works. Thanks for the explanation, Mike.

So the purpose of the operating pressuretrol is only to serve as a back up in the case that the low fire exceeds 1.5 PSI? We also have another backup pressuretrol with only a main scale (no differential scale) that serves as a back up.

To make sure I understand. The burner starts up in hi fire and stays there until the cut-out (14 oz on my system) when it then kicks into low fire. If the pressure drops one ounce (the differential on my system) the hi fire kicks back in until it reaches 14 oz again. Is that right? Is the goal to maintain 14 oz of pressure so the burner doesn't return to high fire during the same call for heat?

I think I understand now what Steamhead suggested. It seems like there are 3 ways to solve the cycling issue then:
1. increase firing rate of low fire mode (I have no idea how to do that, but that's what the tech could do)
or 2. lower cut-out setting on vaporstat
or 3. increase differential of vaporstat

Is that right? If so, is one of the solutions better than the next?

Understanding how it works

Yes, I think you now pretty much understand how it works. You want to start the call for heat at high fire, to rapidly exhaust the air from the system and fill the piping and radiators with steam. Once the vents close and the radiators are hot, the system will start to build pressure. Now you need a lower firing rate (less heat) to prevent the pressure from continuing to increase. This is what your vaporstat is now doing, sensing when the pressure reaches 14 oz and activating low fire which ideally would maintain the 14 oz until the call for heat ends. Your Lo firing rate is slightly less than what is needed to maintain the constant pressure, so as it drops to 13 oz, the vaporstat again activates Hi fire to bring up the pressure to 14 oz again. Because your differential is so low, only an ounce of pressure change is causing the switching. If you increased the differential it would require a greater drop in pressure to activate high fire and therefore the cycling would definitely occur less often, although it might not completely eliminate it.


Increasing the differential is a very simple adjustment, so it is what I would try first. Reducing the 14 oz setting is also simple and easy to try. Steamhead's solution is really the best, but the firing rate adjustment must be be done by a trained tech with the right equipment, so I would save that for last.


Right now, your operating pressuretrol does nothing, because in low fire the system cannot even maintain constant pressure, so it will never reach the 1.5 psi cutout. If however your Lo fire setting was too high, the pressure might gradually increase until it reached the cutout setting, thereby shutting of the burner an preventing the pressure from rising higher.

UPDATE

Firing Rates
I finally got the service tech back to try to clear things up. He told me that there is only one nozzle and the firing rate for the low and high fire is changed by pump pressure. He said that the low fire is 4.25 GPM and the pump runs at 100 pounds pressure and the high fire is around 6.5 GPM and the pump runs 300 pounds of pressure. (hopefully I got all the terms right)

The tech put the vaporstat up to 16 oz. The boiler now stays in high fire for longer than a normal length call for heat. I put it in bypass and it took 27 minutes for the burner to go into low fire. It then only stayed in low fire for 20 to 30 seconds before going back to high fire for a minute. It kept repeating this until I shut the burner. The tech said that we need to be able to have 1 pound of pressure in the radiators upstairs and if we don't have it in the boiler room then we don't have it upstairs. (Even though the pressure didn't reach 1 pound for a long time, the radiators on the top floor still got hot all the way across). I'm not sure what to think here. Question 1: Does that matter that we don't have 1 pound of pressure upstairs????

EDR: I looked at all of the steam radiators and couldn't find the exact kind in Dan's book. Most of the radiators I believe say "Gurney" as the type or maker. It's really hard to read. Anyway, I measured a few of them and since they were the same in many units, I approximated about how many square feet we have total. The steam heat is only on floors 2, 3 and 4. In those floors the total radiators add up to 1200 square feet EDR. I think I read that if you have mains that are not insulated (mine are not all insulated) you should use a larger pick up factor of 1.5 instead of 1.33, but I'd like to know what any of you suggest. Question 2: If we use 1.5 then we have 1800 total EDR, right? The first floor forced hot water radiators and baseboard are not included in the radiator EDR calculation above. I wasn't quite sure how to add that in. Question 3: Does this help in determining the nozzle size? Can someone give me advice on if our sizes are close to what they should be?

Connected Mains. We have 5 mains in the building: 2 long ones to the front with some small branches and 3 shorter ones to the back.

All mains (front and back) share 11ft of 4 inch pipe that rises from the header.

Front Main #1 then goes 70 ft. with 3 inch pipe.
Front Main #2 goes 65 ft. with 3 inch pipe.

The back mains share 7 ft run of 3 inch pipe and then split 3 ways:

Back Main #1 30 ft. of 2.5 inch pipe
Back Main #2 20 ft of 2 inch pipe
Back Main #3 36 ft of 2 inch pipe

Questions 4: When figuring out venting at one ounce of pressure can I divide the air in the first 11 feet of shared 4 inch pipe by 5 (there are 5 mains total) because that way vents in the front and back can share the venting load. Same question with the shared 7 feet of 3 inch pipe to the back of building. Can I divide that by 3 so the back 3 mains share the venting load?

Update about Problem
When I started this thread we could not get the top floor front apartments to heat as well as the rest of the building. This may be a venting issue or the way we set up the heat timer control, or something else. Two days ago the only thing I changed was adding venting to the back 3 mains. I put in one hoffman 75 on back main #1, one Gorton #1 on back main #2, and 1 hoffman 75 on back main #3. Front main #1 already had 3 Gorton #2s and Front Main #2 also had 3 Gorton #2s. I figured that since the back was always warmer than the front, I wouldn't need as much venting. The only reason I added any main vents to the back was because the second floor was getting very hot and I thought adding main vents would help balance the heat across the floors in the back.

As soon as I added main vents to the back, the front apartments (2nd, 3rd, and 4th floors) all got warmer over the next day (around 72 to 74 degrees) and the rear apartments stayed cooler (the rear 2nd and 3rd floor were 67 and 68 degrees and the fourth floor rear apartments were 62 and 64 degrees). It was almost as if my problem switched from the front to the back. I can't figure out what is going on. The only difference that occurred at the same time is that it has been cloudy the past two days as well and the back apartments usually get sun for the whole day. Question 5: Should I add more venting to the back?

Sorry for such a long post, but there was so much information to convey. Any advice people can give is very much appreciated. I hope I can figure this out.

some apartments chilly..some not

this system would be an ideal one to survey with an I.R. camera. with the boiler firing from fairly cold, start in the basement, and see how the mains heat up, especially the risers. use a jumper on the boiler to fire it continuously for the test. repeat the test for the top floor to see where steam arrives first. you may need larger radiator vents on the top floor, with regular hoffmans on the 2nd, and 3rd.
in the absence of a camera, the ouch test with hands on the pipes works well enough. don't concern yourself with apartment air temperature, until you have all rads getting steam almost simultaneously.
on my 3-storey, 1-pipe system, with 55 radiators, and 1,050,000 BTU, i have 6 returns coming back to the boiler, with 3 gorton#2's, plus 1 hoffman 75 on each. the antlers are quite long so there is less likelihood of premature vent closing. since you have a vaporstat, i would reduce the pressure to 8 oz, and see if that makes any difference. steam travels more quickly at low pressures. in the spring and fall with short boiler firings, you need all the air out as quickly as possible. don't forget that the steam chest of the boiler also has air to be removed, so increase that venting. the goal is to have the supply pipes, and returns filled with steam as quickly as possible.--nbc

Nicholas:

Thanks for the response. When I put the boiler in bypass it runs continuously. That should be the same as what you are saying about putting a jumper on right?

Two other people and I ran around the building timing how long it took the risers to get warm about two weeks ago. At this point in time we had gorton #2s on the front mains and no main vents on the back. We checked the third floor risers because the risers go right into the radiator on the fourth floor and aren't visible. During the test the front risers heated up at about the same time as the riser coming up from the shortest main in the back (8 to 9 minutes or so). The risers coming up from the two longer mains in the back actually took a lot longer to heat up (which isn't surprising because they had no main vents below).

Somehow though, the rear apartments were still warmer (72 to 74 degrees) and the top floor front apartments were colder (60-62 degrees). All radiators could and do get hot all the way if the boiler runs long enough. That's when I thought the control was preventing the burner from turning on because the warmer apartments factored into the space average and wouldn't allow the burner to come back on. If the building was perfectly balanced, but the apartments in the back got a lot of sun, they would heat up more and the space average would rise, telling the burner not to turn on. I took all of the warmest apartments in the back out of the equation about a week ago.

I then added main vents to the rear and the situation appears to be reversed as stated above. I guess I should run around and see how long it takes the risers to get warm again. It's been cloudy and stormy the past few days so the back apartments aren't warming at all with the sunlight that normally hits them (that could probably add 4 or 5 degrees). It's weird that only the top floor in the back gets temperatures as low as 60 and 64 while the front is now up to 74.

I can lower the pressure on the high/low vaporstat from 16 oz to 8 oz, but then I wouldn't be able to get a pound of pressure at the top floor radiators like the service tech said I needed... Any idea why the service tech told me that I need a pound of pressure up at top floor radiators? Is that not true? He seemed to think that I needed to have up to a 1.5 PSI at the boiler otherwise I would have "lazy steam". From reading Dan's books and looking at the forum I know that everyone always says lower the pressure and that vaporstats are great to have and if you have the proper venting you can run on lower pressure. Can my 4 story building run well off of the vaporstat? When I asked the tech why we need higher pressure he said, "that's not high pressure, high pressure is 5 or 6 pounds. You need 1.5 pounds for this building." Is that just wrong? Is there any reason we would need more pressure than a vaporstat control can supply? I'm definitely willing to try lowering the pressure, but I'm just trying to figure if what the tech is telling me is wrong or if not, why could be right.

wrong?

yes, less pressure is the new more with steam. a couple of ounces is enough. the point i was trying to make was to follow the steam as it rises from the basement mains, and then track it as it rises from the basement to the top floor. you may have a little obstruction, and never find it unless you follow the steam. the I.R. camera would make the task easier! ggod luck!--nbc

Get a new tech

Looks like you need to get a more knowledgeable tech. Simply increasing the pressure is not going to resolve what appears to be a venting problem. You mentioned that all the top floor radiators were hot all the way across long before the pressure reached 1PSI. If that is true then you really don't need anywhere near 1 PSI to fill the system completely with steam. As Nicholas suggested, I would try gradually reducing the vaporstat cutout setting from the present 16 oz and see how the system responds.

another thought

the heattimer system will only work effectively, and comfortably, when the system is perfectly balanced/vented. why not just use a good steam-rated thermostat until you have worked these problems out. i would suggest a honeywell visionpro with a remote sensor located in the apartment with the most winter exposure [north east?]. if because of it's exposure, you find it too sensitive, then you can set the temperature down to 67 deg.
and yes, you need a new tech who knows something about steam. as you may have read here, the empire state building needs 1.5 psi, but not your building! was he the reason for the heattimer?--nbc

Heat-Timer Control

No, he wasn't the reason for the heat-timer. We had an old
heat-timer before and I guess we just decided to go with the new one because we
met with one of the sales reps who said we would lower our oil consumption a
lot with the new MPC platinum.

I don't have the numbers on me now, but I think we lowered our consumption
around 15% with the new heat-timer. That's before we started adding the venting
over the last month and tweaking the system more. I can take the space lock
feature off or change which apartments are factored into the space lock. Going
forward I plan on lowering the pressure as suggested, adding more venting to
the back, taking the back apartments with sun exposure out of the heat-timer
space lock equation (that way if the building is balanced, but the rear
apartments with sun heat up more, it can't throw the heat-timer off with high
averages causing the burner to not run)

What are the advantages of the Honeywell visionpro and how does it work
differently? How much is it?

Less Pressure & Venting Question

Thanks for the responses, Nicholas and Mike. I'll try lowering the pressure and see what happens. The system will probably stay in high fire for a shorter period of time, and low fire may be able to maintain longer. Do I want the system to stay in high fire until heat circulation is established (eg. stay in high fire until steam reaches last radiator in system and then go to low fire)? What signs should I look for to know when the pressure is at the right setting?

As far as venting: if 3 mains share 11 feet of 4 inch pipe before splitting up, can I divide the amount of air in the shared part of the main by 3 so each of the vents at the end of the 3 mains help vent the air out? This seems pretty intuitive, but I figured I should make sure before spending the money on vents. The total cubic feet of air in that shared part of the main would be .99 cubic feet. If each main needs to vent the air on its own I would need 1 Gorton #2 (1.1 cfm each) on each of the mains in the back to vent the air at one ounce of pressure. If they all contribute to the venting I would only need 1 Gorton#1 (.33 cfm each and much cheaper $$) on each back main.

Thanks

Less pressure

Yes, ideally you would want the boiler at high fire until all the radiators were hot and filled with steam. Until that happens, the system will not be able to increase pressure because the vents are still open and all the steam is condensing as fast as it can be produced. Once the vents close and the radiators are at steam temperature, steam cannot condense as fast as it is being made,  which causes the pressure to start to rise. At this point you want the boiler to go to low fire so the steam production is just adequate to meet the ability of the radiators to condense it. Now the system is in equilibrium at low fire and should operate at constant pressure until the call for heat ends.


I would continue to lower the vaporstat setting until the system remains in low fire without excessive cycling until the call for heat ends. If you reduce the setting too much,  the burner will go to low fire before the furthest radiators are completely hot and the heating will become less even. You really want a setting in between that point and where you are now.


The Heat-timer you have is more suitable for your application than the Vision-Pro because it allows for multi-indoor sensors and also takes into account outdoor temperature when calculating the heating cycles. Getting it to work correctly is more a matter of determining which apartments should be sensed to provide the most accurate overall control of the building