High Pressure on Steam Boiler

cokeefe

Hi everyone, I recently bought a house with an old steam system and have come across an issue with my boiler that I have not been able to figure out by reading past posts on here.

I noticed recently that the pressure gauge on the boiler is reading very high pressure when the boiler is on. It will drop once the boiler is off, but this takes a while and it only turns off when the thermostat temperature is reached. For example the pressure will build up to 20 psi (I know this is way too high) and then drop back to 0 across the next few hours.

Reading posts on here I figured my pressurtrol was not working properly and that the issue may be because of a clogged pigtail. I just replaced the pigtail today with a new brass one and added a second pressure gauge off a tee. Unfortunately the store only had a 0-15 gauge, but I wanted to make sure the issue wasn't because the other gauge was completely broken so I still bought it and put the gauge on (it is facing sideways because I forgot to buy a second elbow lol).

After replacing the pigtail, draining the water through the low water cutoff, refilling the water, and adding the new pressure gauge- I turned the heat back on and there was no change. The new gauge is not reading any pressure and the pressuretrol is not reacting to the building pressure in the boiler. I can manually trip the pressuretrol, which will cause the boiler to turn off. I was also able to pour water through the pigtail, down and out the low water cutoff (which makes me think there is not a block from the LWCO to pigtail).

I'm not sure if this could be related, but I don't believe there are any main vents on my pipes.

Overall I'm very confused as to what may be causing this problem, any help is appreciated. Pictures are attached for reference.

JohnNY

Why didn't you put the tee on the pigtail on the run and the gauge on the bull with the elbow?
It sounds like your pressuretrol isn't working.

KC_Jones

I think I need a clarification here.  The new gauge is reading no pressure, but you still feel there is a problem.  Why?  If the brand new gauge isn’t reading any pressure, the old gauge was most likely faulty.

Just a bit confused about what problem you think you have after replacing what presents as a faulty gauge.

ethicalpaul

I too am confused. I swear I read that pressure was high and then he said that now it's unchanged with no pressure. That sounds like a change!

Why didn't you put the tee on the pigtail on the run and the gauge on the bull with the elbow?

Because a lot of people not in the plumbing trade don't know to think of the orientation of a tee and don't know the terms "on the run" and "on the bull" But I would say this issue is secondary.

to the Original Poster: Is the LWCO being "blown down" weekly? Is there a chance it is blocked? (edit: on re-reading I see he says there is flow through it so probably not)

Another note: The pressure does not take an hour to drop after the boiler stops firing. It's almost instant.

cokeefe

Thank you everyone for the responses. I believe I did try to orient the gauge like that initially, but wasn't able to fit the gauge next to the pressuretrol without it facing down at the floor.

I guess I'm saying there was no change because the old pressure gauge continues to rise as steadily as it was before I replaced the pigtail, but as you've pointed out the old gauge could be faulty. I actually didn't consider this just because the needle on that old gauge seems to move so consistently as the boiler runs. Also to clarify, the old gauge is still on the front of the boiler and it's an internal syphon gauge.

I think another reason I was worried about the new gauge just not working or not reading any pressure is because the pressuretrol never seems to cut in. The boiler will run until the thermostat cuts it off and this can be for an hour or more. I have never had the pressuretrol cut in while the boiler is running. I realize now that this may not be a bad thing, but I figured at some point I would get some king of reading on the new gauge even if it was as low as .5psi.

Thank you all for your help, as someone who has never worked with steam it can be a bit challenging figuring out exactly what normal operation is.

ethicalpaul

How long is your boiler running on a typical call for heat? it may in fact be correctly sized (SHOCKER!) and not building any pressure.

If you want to force it for a test (I would), you can make it recover from a 7 degree setback with blankets on some of the radiators. You should see some pressure build then.

Jamie Hall

The old gauge -- the one built into the boiler -- may well be faults -- and acting more as a really bad thermometer than a pressure gauge. Consider: if it is blocked from really reading the boiler, the water trapped in it can't go anywhere. Now if you heat that water up, it expands and -- internally -- raises the pressure in the gauge. So... it goes up slowly as the boiler heats up and then sits there when the boiler is running, then as the boiler cools off it slowly drops down again. You could probabbly calibrate it as a lousy thermometer...

Back to reality -- I suspect that @ethicalpaul may be right -- that for once we have a properly sized boiler and it is doing exactly what it is supposed to do. Try his trick of raising the temperature a lot -- and don't expect that 0 to 15 gauge to move much. Even a pound isn't much on that scale.

Oh and don't worry about the gauge orientation. It'll work just fine as it is.

cokeefe

If I'm raising the temperature about 2-3 degrees for example, it might take 45 minutes to heat up the radiators. I haven't timed it, but that is an approximation. I'll definitely try testing it now with raising the temperature up 7 degrees.

Thank you for that explanation Jamie, that definitely does make sense. Do you think it would be worth trying to replace the old built in gauge with a new one? Or just ignoring it and referring to the new gauge off the pigtail will suffice?

ethicalpaul

Just ignore the old one. Code requires one with that scale, but it doesn't require that it works, and almost none of them in the whole wide world do work

Also I see that you don't think you have any main vents. See about getting them, at least one per main pipe that your system has. We can help.

cokeefe

Thank you so much for your help. I tried raising the temperature and putting blankets over the radiators. About an hour and 15 minutes later the gauge registered increased pressure (about 2psi) and the pressurtrol kicked in. I guess I didn't realize how long it could take that long to build any pressure and that the needle may not move at all while the boiler was running.

I'll take a look at some of the information on main vents and see about getting those set up.

Thank you everyone again for all your help, it is greatly appreciated.

Long Beach Ed

ethicalpaul said:

Just ignore the old one. Code requires one with that scale, but it doesn't require that it works, .

Eh, where did you get that from?? In the world of codes, an inoperative gauge is not a gauge.

ethicalpaul

Long Beach Ed said:

ethicalpaul said:

Just ignore the old one. Code requires one with that scale, but it doesn't require that it works, .

Eh, where did you get that from?? In the world of codes, an inoperative gauge is not a gauge.

Let me turn this around and ask you, when's the last time you saw an inspector check the gauge?

Long Beach Ed

ethicalpaul said:

Code requires one with that scale, but it doesn't require that it works,
...
Let me turn this around and ask you, when's the last time you saw an inspector check the gauge?

That's not very ethical, Paul.

BobC

Around here the only thing our inspectors are interested in are their tee times and that all important 19th hole.

i do think that 30# gauge should be operational if not very accurate if nothing else to warn someone something very wrong is going on before liftoff occurs. You really don't want to be in the room when the boiler pressure relief valve goes off.

Bob

Mad Dog_2

For the most part most gauges that come with the boilers are minimum quality where that wasn't case years ago.  If you really want to see whats going on Order a Weksler Liquid steam gauge that reads in ounces only goes up to say 5 psi.  You still need the one that comes w the boiler as per code. (30psi I think?)   And switch to a 4 PSI  Vaporstat to dial it in. Mad 🐕 

EBEBRATT-Ed

Soundslike it is working fine. The pressure control works and shuts off the boiler that is the most important thing. Ignore the old gauge. The fact that the boiler heats the building and does not build pressure is a good thing