Is the Pressure level normal?

olson221

Hi, I am a newbie. I have a silly question to ask about my Williamson steam boiler. Is it normal that when thermostat calls for heat, the boiler runs abt 10min till pressure hits 5psi and it stop for a few minutes till pressure drops close to 0. And it keep repeating the same way. Is there any way to increase run time to 20min? Such as decreasing anticipating pressure or clean air vent of radiator. Please advice. Thanks a lot.

Jamie Hall

No, that is not normal. First off, it should cut off at about 2 psi, not 5 psi. There is a control on the front called a pressuretrol -- most of them are a blue grey box with a scale on it. Could you post a photo of that and we can tell you where it should be set at?

Second, that short a run time indicates that your main vents -- if you have any at all -- are way too small or just not working at all. Can you wander around in your basement and find the steam main or mains, and then look near the end of it (them) and see if there is a vent on there? And take a photo of that and post that. Also, how long are the mains, and what diameter?

olson221

Is this the main vent? How do I know if it’s working or not? I know that pressure should really stay constant at 1-2psi while boiler is boiling. Could please you explain why it will stay constant? Don’t pressure keep rising if boiler keep boiling? Unless pressure is releasing somewhere. Why my pressure goes up so fast? In 10min to 5psi.

KC_Jones

Pressure is a function of venting capacity and boiler size in relation to the emitters. If you don't have enough venting or the boiler is over sized (we usually see both around here) you will build pressure.

One thing to be clear about, you do not want pressure....ever. Pressure is bad on a steam system, anyone that tells you differently doesn't understand it. The only pressure you should see is the amount required to overcome the "friction" of the steam getting through the pipes and pushing air out. Lower is better. Someone on here did a calculation of the "friction" of their system a few years ago and it was extraordinarily low.

That is not your main vent it is the pressure relief valve. The main vent will be out on the system piping either somewhere near the last radiator on the main or where the dry return piping turns down to the wet return. We have seen some other creative locations, but those are the 2 most common.

The white wheel on your pressuretrol should be set to 1 and the setting on the front should be as low as you can get it without disengaging the linkage. Looking at your settings, if you are getting to 5 (if the gauge is correct) I would suggest your pigtail is probably clogged.

olson221

Pigtail wasn't clogged as we just replace the pressure gauge and switch pressuretrol differential dial to 1. I don't think my system has a main vent. Now what can we do? replacing bigger air vent at the radiator would help running the boiler longer?(longer time to build up cutoff pressure limits?)

Jamie Hall

A bigger vent on a radiator really won't help at all -- and may lead to having water hammer at that radiator. Further, I assume that there is more than one radiator?

You may well have no main vent -- or a very old malfunctioning one. Try following the steam mains in the basement, and see if you can find anything which looks vaguely like a vent -- or even odd at or near the ends of them. Take a photo of it if you find such a critter, and post it and we can comment...

olson221

I went thru whole main pipe. No such vent uncles hidden within floors. However there’s also another clear pressuretrol between dry return and wet return area. I guess this is place for main vent. But I have this instead.

Jamie Hall

That pressuretrol in the photo is a manual reset safety high limit -- and hopefully never gets tripped.

I have a suspicion that you might be well served to get a good steam technician in to look over your system and see about getting it running up to its potential. Where are you located?

JUGHNE

Show us your boiler piping, floor to ceiling, both sides and include that 2nd pressure control.
It might have been where an air vent was.