Heating Help

It's the same...

@ February 12, 2010 7:38 PM in 2 pipe steam problem

It's still the same concept.  What matters is the relative pressure difference between the two points.  Just watch the glass tube.  If it doesn't drop much, then, by definition, water isn't stacking up in the return.  If the water level in the boiler goes down fast (ie not from creation of steam), then you might have an issue with a flooded return.  But it takes a special kind of screwed up system for this to happen.

A few things...

@ February 12, 2010 4:34 PM in 2 pipe steam problem

I think there is some misunderstanding about boiler pressure and the impact on raising the water level in the returns.  First, pressure in the boiler does not cause the water level in the returns to "stack up" on a one-for-one basis.  In other words, a boiler at 1 psi of relative pressure (27 inches of water) does not cause the water level in the return lines to rise by 27 inches.  What matters is the difference in pressure between the boiler and the the pressure at the point where the dry return turns into a wet return.  That pressure difference is what's most important and it will vary from system-to-system and will also vary during the cycle.  If you have a massively oversized boiler, then this pressure difference will be strongest at the beginning of a cycle and can cause the water to literally shoot out of the boiler into the returns.  (A properly sized equalizer helps stop this effect even in a massively oversized unit.)

Assuming the sight glass is working properly, if you aren't seeing a massive reduction in the water height in the boiler, then you aren't going to have a problem with water stacking in the returns (and this flooding a vent).

I know that NBC and Jamie know this - just think we need to be clear for the benefit of others.

Dry steam

@ February 5, 2010 3:11 PM in DROP HEADERS

Drop headers help the steam shed excess water before heading into the mains.  Old boilers used to perform the drying process internally, but the limited inside space on new boilers forces some of this process to the header.

Sounds Normal

@ February 5, 2010 1:42 PM in Uh Oh. Cracked?

Sounds normal to me.  Remember that when you start the system, the steam pushes the air in the rads out of the system.  That air is relatively high in humidity.  When the system turns off, dry air from your house rushes into the rads and absorbs water, which then gets pushed out on the next cycle.  Even a system that has perfectly working vents loses water in this way.  For your system, a half a cup a day seems about right to me.

Vacuum

@ February 4, 2010 9:18 AM in Where are we on the Gorton #2 quality?

When the system turns off due to pressure, those main vents will (should) reopen to allow air back into the system to satisfy the vacuum that occurs when the steam collapses.  Are you sure that steam/air is coming out?  If you are basing this on sound, you may be hearing a (loud) whistle as air rushes into the mains through the vent.

Alerts

@ February 2, 2010 4:56 PM in 30 day Vacation - How much setback

Assuming you have a permanent internet connection, you can get a couple of thermometers and perhaps a water alarm for pretty cheap.  They can broadcast temperature (either regularly or if it drops below a particular temp) to an email account.  You can also get similar alarm platforms that will do the same by dialing out over a regular phone line.  It's pretty cheap to do and adds a lot of secutiy for people in your position.

H75s

@ January 31, 2010 10:55 AM in leaking gorton #2's

When both are working as intended, two Hoffman 75s are about equal to one Gorton #2.

I posted a few days ago...

@ January 31, 2010 1:54 AM in What is the life expentency of a vent?

When I changed my vents a little over a year ago, I used a mix of VairValves, Hoffman 1As and Gorton Ds.  All of the VariValves have failed in less than 2 years.  In my opinion, they just don't work.

My thoghts

@ January 29, 2010 3:02 PM in Removing radiators

I would cap the takeoff as close to the riser/main as possible.  Heating pipe is just a waste.  Plus you never know when a perfectly fine pipe will spring a leak.  Cap it as close to source as possible.  I'd probably leave pipe that's buried in a wall well enough alone, though.  It can serve as a nice conduit for things like fiber and ethernet cable.

Thoughts on One Pipe Vents

@ January 29, 2010 2:31 PM in Thoughts on One Pipe Vents

I replaced my boiler in 2008 in connection with a major house renovation.  Some radiators were moved as part of the process.  Everything was eventually done correctly (in no small part due to the guidance from this board and from Dan's books).  I have gone through one full heating season and am more than half way through the second now.  When I redid the system, I had all the radiators sand blasted and refinished.  I also, of course, took the time to replace all the vents.

Total sq ft of rads is about 1300.  A total of 19 rads and 4 convectors.  As a bit of a test, I used a combination of VariValves, Hoffman 1A and straight Gorton D vents.  I used Hoffman 75s as the main vents -- I just trusted the design better than Gorton #2s.  The Hoffman 75s have been great.

So far, every single one of my VariValves has failed.  Almost all of them become stuck closed or mostly closed.  Even when working, they spit like a camel.  Note that I have very dry steam and run at 1 to 2 oz of pressure.  I have a vaporstat that kicks in at 5 ounces and it almost never kicks in as the t-stat is satisfied before I get much over 2 ounces unless coming back from a setback of more than 6 degrees (vacation).  The water simply didnt want to drain out of these VariValves.  All of the Hoffman 1As and Gorton Ds continue to work perfectly.  Haven't had a single one fail on me.

I have since replaced all of my VariValves with Hoffman 1As.  In a couple of cases, due to the size of the radiators, I tapped the rads and put in a second 1A vent to get similar venting capacity of a VariValve.
I really wanted the VariValves to work.  They are small and don't "clank" like the 1As do when shutting.  But, at least for my system (which runs great), they simply didn't work.

Just my thoughts.

My thoughts

@ January 28, 2010 1:41 PM in Remove redundant steam mains?

You won't save much, if any, on efficiency.  The boiler will continue to burn the same amount of oil/gas per minute and, my guess, is that you won't be running the boiler for any less time after the retrofit, particularly if those mains are well insulated at the moment.  You will likely need to replace those loops with bigger pipe (assuming they were sized correctly to begin with).  So, if you have two mains of 2.5", you may need to replace them with a single 3.5" main.  That 3.5" mass won't be equal to the mass of 2 x 2.5" pipes, but it ain't gonna be far off.
Do this for aestetics and other reasons, not for expected energy savings.
Also, if you do this, start your calculations from scratch.  Use a properly sized main loop with real returns and parallel flow.  You'll be thankful you did.

Water Hammer

@ January 24, 2010 10:40 PM in connecting dry returns above water line

The biggest issue this causes is potential water hammer as the steam runs up the condensate line.  I haven't seen it slow down venting, though.

OK

@ January 23, 2010 12:12 PM in wide open 1/2" pipe

ok...then i think you have an issue...have you turned off every radiator so that your open port is the only exit?  If so, and it takes 7 minutes to reach the open port with warm/hot pipes, then your boiler is either way undersized or isn't producing the rated amount of steam.

Try this...

@ January 23, 2010 11:56 AM in wide open 1/2" pipe

Turn on your boiler and put your hand on the part of the horizontal main closest to the boiler.  Wait until steam hits that point (you will know when this happens...it will go from cold/warm to very hot in a second).  It won't burn you, but you'll know when steam hits that point.  Now immediately start timing and go to the open port at the end of the main.  When steam hits the port, stop timing.  That's the vent time of your main.  My guess is that you will see it is about 3-4 min, which is fine.  Just sounds like your boiler takes a bit of time to start the steam process.  You could have an undersized (or underfired) burner relative to your boiler.  Also check that your boiler is not overfilled with water.  You may want to zee how fast the boiler makes steam (from a cold start) with relatively low water vs relatively high water.

Boyle's law

@ January 20, 2010 5:47 PM in plastic tubing level doesn't match guage glass level?

Capillary action would be negligible in a plastic tube of that size (and would work in the opposite direction as stated above).
Assuming the sight glass valves are fully open on the top and bottom, the only explanation is that the pressure from the "air" in the boiler and the return pipes, taken as a whole, is less than the atmospheric pressure in the basement.  Probably because the "air" inside the boiler and pipes has a different composition (saturated with water vapor) and temperature than the "air" in the basement.  Remember that Boyle's law (pV=nRT) only works for an "ideal" gas.  You are working with two different non-ideal gasses in your setup.
First thing I would check, though, is the top valve in the sight glass. To make sure you don't have a vacuum under cold conditions.  That's happened to me a few times due to crud.

When running

@ January 20, 2010 1:53 PM in plastic tubing level doesn't match guage glass level?

Is the level difference there at rest, when boiling or all the time?

The standard...

@ January 17, 2010 10:00 PM in piping

Black pipe IS the standard.

Basement system

@ January 17, 2010 9:22 PM in Hot water baseboard on steam system

I have one pipe steam sized about right for my house.  Radiation is 1250 sq ft and boiler rating is about 1500 sq ft.  I have the system running well at about 2 oz of pressure.
I'm considering adding a water baseboard or water rad in my basement (exercise room that's about 55 degrees in winter).  The rad or baseboard will be significantly lower (at least a foot lower) than the minimum water line in my boiler.
I have read Dan's articles on this, so I'm up to speed.  But since this zone would be under the boiler water level and I'm not looking for any temp control, I'm wandering if I can simplify a bit.
Question - Anyone see a problem with just using gravity and basic thermodynamics to create a loop (without a bypass to cool the water)?  I'd control the flow with a simple ball valve.  Will I have steam flashing?  Remember that the min boiler level will be a foot (or two) above the highest point of this loop.  If this works, I would prefer it to pumps and bypasses.

Vaporstat Adjustment

@ January 11, 2010 1:38 PM in why do Honeywell vaporstats suck so badly?

I woke up this morning and my vents were absolutely hissing.  I normally operate a very quiet system around 2 oz of pressure (I changed from an oil to gas boiler last year and had it properly sized).  My vaportstat never kicks in (thermostat is temp satisfied before pressure builds), but I have it set to kick out at 8 oz and back in at 2 oz.  I went downstairs - my gauge was reading 14 oz of pressure.  WTF!  I played with the screws on top and realized I was having the same problem as gerry.
Pig tail is fine (ie, not clogged - because the gauge is on the same tail with a T).  I had to really crank the top screw down to get it to trigger, and then it wouldn't re-energize.  Where is the adjustment screw that can make this p.o.s. work?  I would actually like this thing to work so that the few times a year I need it (coming on from a deep set back when out of town for a  few days, for example), it works.  Where is this special adjustment screw you speak of?