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The Wall
Jamie Hall

Jamie Hall

Joined on September 16, 2002

Last Post on April 24, 2014

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Swivel joints

@ March 25, 2014 5:35 PM in Short Cycling Despite First Time Main Vents Installed

are not what is meant, rather swing joints -- and swing joints are any configuration of elbows and nipples which can allow the spacing between one end of a pair of parallel pipes to change relative to the other end.

For example.  Come straight up on two risers.  Elbow over 90 degrees.  Reasonable length of pipe.  Elbow up 90 degrees, continue up.  Or better yet...

Make a drop header with two risers (let's assume 3" risers): go straight up 24", 3" pipe.  Elbow over 90 degrees on both risers.  Go horizontal (pipes parallel) with 3", say 15".  Elbow DOWN 90 degrees.  Go straight down with 3" say 12 inches.  Line from the riser at the front of the boiler, elbow 90 degrees to horizontal 3", in line with the line between risers.  Go back the distance between the risers.  Back riser hooks in with 3x3x3 T.  Now go back a bit more, and hook your steam mains into the top with 3x3xwhatever Ts.  And back a little bit more and hook your equalizer in with a 3x2 reducing elbow, 2" down...

Steam to shutoff valves?

@ March 25, 2014 5:27 PM in No steam reaches shut off valves.


There's a contradiction here.  What sort of system do you really have, and how is it controlled?

I totally agree!

@ March 24, 2014 7:30 PM in i got to get rid of this steam heat system, i got questions

I just didn't want to sound heavy handed or cheap!  The radiators in the museum/house which I care for have just been wirebrushed, primed, and painted with quality acrylic and hold up just fine -- and look fine, too.

Did you get anywhere?

@ March 24, 2014 7:27 PM in Pressuretrol mystery

Pressuretrols are usually pretty bullet-proof critters, and the microswitch can usually take a pretty good amount of current -- although like any switch, they can be overloaded.  Usually, though, if a switch fails from overload it will fail closed (contacts welded) rather than open -- and whacking it won't help!

If you still having the nightmare, can you put a low pressure gauge on an independent pigtail to see what is really happening to the pressure?

And what are the settings on the pressuretrol?  Is it possible that the cutin pressure is low enough that it isn't being reached reliably?  That can happen...

Just to add to the discussion...

@ March 24, 2014 7:23 PM in Short Cycling Despite First Time Main Vents Installed

first, your system is behaving exactly as expected when dealing with a combination of a slightly oversized boiler (probably not that much oversize) and a setback. 

The principle is this:  if you wish to raise the temperature of a space from one temperature -- say your 62 -- to another -- say your 68 -- it is going to take a certain amount of heat input to do it.  BTUs.  That's inescapable.  Now your radiation can only pump out BTUs at a certain rate; so and so many BTUs per hour (it's to a very close approximation 240 BTU per hour per EDR).  Then there is the heat loss from the envelope, which varies with the difference between inside and outside air temperature.

So.  It will take the radiation a certain amount of time, determined by the number of BTUs needed to raise the temperature less the heat loss through the envelope, to raise the temperature from the setback.  However, the boiler is slightly oversize, and puts out more BTUs per hour than the radiation can emit.  Once the radiation is all up to temperature, there are only two things that can happen -- either the pressure goes up, since the steam can't condense any more, or the boiler can be turned off on pressure.  The latter saves a good bit of fuel and money in comparison with the former, as well as being much better for the system!

And that is the "short cycling" which you are seeing.  It has nothing at all to do with venting, and all the fiddling with venting in the world won't make a bit of difference to it.  Neither will changing the pressure settings on the boiler, incidentally.

The Nest -- which in my mind is an exceedingly expensive solution to a non-existent problem, but never mind that -- is doing what you ask it to do.  Other programmable thermostats would do the same job if asked to do the same thing.

There are two ways to eliminate the cycling on pressure when all radiation is filled.  One is to reduce the firing rate on the boiler at that point -- just as when you are driving a car, you back off on the gas when you reach your desired speed.  You can't just downfire the boiler all the time -- you'd never get the radiation quite full, just as you can't accelerate your car with the same throttle setting you cruise at.

At the present state of the art it is simpler to cycle the boiler to maintain pressure where it belongs than to modulate it -- and only very slightly less efficient.

The other way is considerably simpler: limit your setback, if any, to what can be recovered before the boiler starts to cycle on pressure.  And that depends on the boiler and the attached radiation and, to a certain extent, on the structure.

Is there a possibility

@ March 24, 2014 4:25 PM in END OF MAIN AIR VENTS

that where the radiator vents are now there were once crossover traps?  They look like ordinary radiator traps, but the piping is up from the steam main, the over to the trap inlet, then down from the trap outlet to the dry return.  They function in exactly the same way as main vents -- say Gorton #2 or the like -- in allowing air, but not steam, to escape from the main.  It then goes into the dry returns and is usually vented from them -- often and the boiler.  Any condensate is taken care of by the drips to the wet returns.  Works like a charm.

And does not need an F&T!

Do post pictures as Steamhead suggested...

If there are end of main air vents --

@ March 24, 2014 12:31 PM in END OF MAIN AIR VENTS

big ones -- the little radiator vents aren't doing much.  But something sounds a little like a late modification here.  It would help to know if there are dry returns on the system which extend to the ends of the mains, and if there are wet returns which also extend to the ends of the mains -- and, if so, if there are drips from the mains and the dry returns to the wet returns.

Glad we convinced you!

@ March 24, 2014 12:28 PM in i got to get rid of this steam heat system, i got questions

As to painting radiators -- the remove, sandblast, and powdercoat is the best way to go.  Does a nice job.  It is not, however, the only way to go.  You can leave them in place and wire brush them, then paint with a good metal primer such as Rustoleum, and then paint them to match the room or whatever.  You will find that there are two schools of thought on the paint, though; one school says you have to use high temperature paint.  The other school (to which I belong) has had perfectly good results with using the same high quality acrylic (Benjamin Moore in my case) that is used on the walls.

The other thing to do is to start thinking about the system itself -- and the best place to start with that is to get yourself a copy of the book "We Got Steam Heat" from the shop on the Wall.  "The Lost Art of Steam Heat" is another, but is a little more formidable (although quite readable).  Steam heat isn't really rocket science, but one does need to know a little about how it is supposed to work to make it work properly -- unfortunately, not all that many plumbers have learned.  You may find that there are aspects of your system which aren't quite as they should be.

You can always ask questions here on the Wall -- we try to be as helpful as we can be!

You will also want to get a good, reliable oil burner and boiler technician to come in and thoroughly clean the boiler and properly clean and adjust the oil burner.  That alone can make a tremendous difference in fuel usage.

You  also want to pay attention to the envelope of the house.  Insulation is always a good idea, but not always that simple with older houses, although in most cases there are insulation materials which can be blown in (I'm not keen on foam, as it can damage the plaster as it expands).  Infiltration is the big problem; good storm windows work wonders (replacement windows are not, in my view, a cost-effective option; a good double hung -- maybe with a little adjustment -- plus a good storm window works just as well) and good storm doors help a lot too.

Pennsylvania winters are just a little tougher than California ones!

Good luck, and stay with us!


@ March 23, 2014 7:43 PM in i got to get rid of this steam heat system, i got questions

Why take it out?  I agree that it may not have that Kalifornia charm, but it's there, and it works.

A pellet stove is a fair amount of work, but as a secondary heat source it does have its points -- although saving money isn't one of them.  However, it will not heat your upstairs particularly well.  This may not be a problem if you like cool or cold bedrooms.

Also, it won't run itself when and if you go away on vacation or something of the sort -- what do you propose to do then?

Third, it is highly unlikely that ripping the automatic heat source (your steam system) will make your insurance company or local building inspector happy -- and will make your house essentially unsalable in the future.

So... I would strongly recommend leaving it in place.  You might even consider investigating the system a little, and learning something about it to see if just maybe its efficiency could be improved -- which is very likely.

I might add

@ March 20, 2014 2:29 PM in Two pipe system -return main with vent off mainly sucks in during cycle

that you note that the water will come out of the vent connections at the end of the cycle.

A vacuum cannot do this.  This is a pressure problem.

A couple of additional thoughts

@ March 20, 2014 2:26 PM in 2 Pipe Steam Woes - Cold Zone Of House

in addition to what NBC has noted.

First, is there any vent at all at the end of main C in the addition?

Second, check the pitch of everything.

Third, is the boiler big enough?  As NBC noted, you need to add up the EDR of all the radiation on the system, and compare it to the required pipe sizes as they go along (the tables to which he refers are in The Lost Art of Steam Heating) and then to the rated EDR of the boiler.

I have been thinking about this one...

@ March 19, 2014 7:00 PM in Two pipe system -return main with vent off mainly sucks in during cycle

but without really looking at the whole system, I can't say just where the vacuum may be forming -- and, more to the point, why the Gortons aren't releasing it.

I will say that it looks as though the system has been repiped -- possibly extensively repiped -- at some point, judging by the use of copper in a dry return (which really isn't a good idea), which makes me wonder just a little about what else might have been done.  A full diagram of the system would probably help.

As to steam main venting -- in principle an F&T at the end of the main, leading to a dry return and a drip , should act as a main vent.  It is one of the standard ways of venting mains.  Usually, though, there is more or a drop to the F&T -- and more of a drop to the dry return.  With that little difference between the elevation of the steam main and the dry return, I would have expected to see a crossover trap, with both the steam main and the dry return dripped to the wet return, and a main vent or set of main vents near the boiler.

But you do need main venting, in addition to the dry returns.  Yes, the main is vented through the radiators and the traps into the return, but without main venting (or crossover traps, which do the same thing) the heat will be slow to get to the far end of the main, and will be uneven particularly in warmer weather.

Your short cycling

@ March 18, 2014 9:21 PM in Steam Boiler Short Cycling from Pressure

is absolutely typical of a situation where the boiler is somewhat oversize for the system.  Don't raise the pressure -- you're OK where you are.  Raising the pressure won't make a bit of difference, except burn a little more fuel.

You may be able to downfire that system; check with a really good burner and boiler tech. on that.  It's often possible, and you wouldn't need to downfire all that much; I'd try about a 10% reduction first, and see what happened.  You don't want to go too low...

I don't know Carlin gas burners.  Carlin oil burners are, however, somewhat noisy.  Nature of the beast.

You should not

@ March 18, 2014 9:16 PM in Two pipe system -return main with vent off mainly sucks in during cycle

be getting a vacuum in either the returns or the mains, at least not with those Gortons on there -- unless they are somehow seeing steam and closing.  Since they are on the return (at least that is what it looks like from the picture) they should never see steam.

I'm not a big fan of F&T traps.  Crossover traps and drips at the end of a steam main; F&Ts, generally no.  Are there vents on the mains as well as vents on the return?

Or am I misinterpreting the picture?

Also, what pressure are you running at?  There is a remote chance that you are backing water out and far enough up to get to that return, if the pressure is high enough (remember that 1 psi is 28 inches).

Hadn't thought of that!

@ March 17, 2014 5:39 PM in Controlling feed rate for skimming

Neat idea.  Perhaps you could create a hose with female couplings on both ends, hook one end to a boiler drain (if you have one!) and the other to a convenient hose outlet?

I would be very much inclined

@ March 17, 2014 12:15 PM in In ground condensate line replacement

to use Aquatherm or equal, although either copper or ductile iron could be used instead.  I wouldn't use steel, even galvanized or tar/epoxy coated.  If you think you have trouble with corrosion on coated steel pipe, take a look at what the pipeline companies do -- coated, wrapped, and then cathodic protection and they still have major corrosion problems.

If you were to use Aquatherm, the best way to avoid having a potential steam problem in it is to make sure that it is always -- always -- water filled.  And the way to do that is gravity -- If your condensate receiver (I presume you are using one?) is a couple of feet higher than the highest point on the buried line, that should do it.  Otherwise, something like a false water line arrangement before it gets to the receiver should work rather well.

The temperature

@ March 17, 2014 12:05 PM in How to gauge boiler temperature?

isn't that critical.  What you want to do is to avoid having it boil -- but keep it nice and hot.  Just below or at a simmer, in fact.  However, unlike a pot on a stove you can't see it -- so it is a little tricky to do.

Quite possibly the best bet is a candy thermometer (really!), and measure the temperature of the water coming out; if it's below about 180, switch the burner on and let it run until it gets up to 200 or so, maybe a little higher.  Then turn the burner off and let it cool down a bit.  And so on.  Until you get sick and tired of baby-sitting the thing.

13 minutes

@ March 16, 2014 7:57 PM in Check valve

does seem a bit long, but could I ask how that is measured?  If it's from the time the burners first fire to the first sign of condensate coming back into the receiver, then it may not be.  The real question is how long from when steam really starts to form (the header gets steam hot) to that first condensate return.

You could indeed run the system piped to bypass the condensate receiver, and it would be a good test if you can do it without major complications.  However, when you do, keep an eye on the boiler water level, as that is your real criterion.  If your water level doesn't drop that much, and then holds steady while the boiler is firing, then you should be -- in my opinion -- better off with a straight gravity system.

You might also consider the condition of your wet returns.  Is there any way to flush them out?  They do sometimes get gooped up and slow for that reason.

One usually doesn't worry that much

@ March 16, 2014 6:16 PM in Determining Boiler Condition

about the water side of a boiler.  The fire side, yes indeed -- there are access panels or ports or what have you which allow a good technician to get in there and get all of the soot scraped or brushed off and knocked down into the firebox, and then, of course, the firebox gets checked and vacuumed and generally all tidied up.  Then the burner goes back together and you adjust the air and oil or gas and off you go.  And all that should be done, as a minimum, once a year.

As I say, the water side one doesn't usually worry about.  However, if you wanted to, after you had drained the boiler you could get in there through any of the various ports with a mechanic's fibre optic borescope gadget.  They aren't all that cheap (!), at least for decent ones, but they do let you see what's happening.

As I read the manual...

@ March 16, 2014 4:08 PM in Check valve

for that baby, it says, "Where condensate return is not adequate, a low water cutoff and pump control, condensate receiver, and condensate boiler feed pump should be added" and it gives you a figure.

But the key words are right at the beginning: "where condensate return is not adequate".  It does not say it is required; only if the return is too slow.

So... the question is, is your return too slow?  Do you know?  if it is, have you investigated why it is slow?  It would be much more satisfactory to fix the slow return problem and let gravity drive, if you can.  Which, unless your place is really immense, I expect that you can.

Forgive me, but I think someone mis-read the manual.

Correct on both counts...

@ March 16, 2014 3:58 PM in Excessive Makeup Water Use/Proposed Elimination of Condensate Return Tank

" Point of clarification: Your are correct about the “pair of parallel
flow steam mains with drips … .” But regarding the “… which go to the
wet returns,” as I understand it, and what you and Nicholas (next post)
are confirming, is that the contractor turned the returns into dry
returns “twice:” first, when he installed the CRT, and second, when he
raised the height of the CR lines."

In other words, he messed up twice in a row.  His job is rather simple: un mess it up.  If that's a verb.  As Steamhead hinted, it would be nice if he admitted that he goofed...

I'd be worried

@ March 16, 2014 3:54 PM in Heat pump only, or combo?

about the low temperature end of things, too.  But I'm not familiar with the new generation heat pumps... but that is something I'd want to check out very thoroughly indeed.
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