Regulating pressure in a single pipe steam system

Pete Novak

First of all I just want to say this is a fantastic site, and I'd like to thank you all for your help. I own an old 4 unit apartment that is undergoing renovations. In order to save money on heating, I turned off 8 out of 11 steam valves. (So the system could concentrate on heating the rooms that being used) The system is a single pipe steam system and it was running around 5psi. Then I fixed a leaky steam vent and a leaky steam valve. This caused the pressure to shoot up around 8 or 9psi. Needless to say when the pressure got this high, other things started leaking. I realize the system should run around 2psi. How do these systems monitor steam pressure, and how can I adjust it??

Thanks!!

Steamhead

Pete, find a good steam man

and get him over there quickly! Your system is building way too much pressure and if that is not corrected, something could blow!

Now to answer your question- Each boiler has a pressure limit control that stops the burner if the pressure gets too high. Usually this is a small gray box. But sometimes these things malfunction, or the pigtail below the control gets plugged. Or someone sets them too high. One-pipe steam should not go over 2 PSI.

The next line of defense is a safety valve on the boiler. These are usually set to blow at 15 pounds. But since the current level of pressure is causing leaks, I don't think you can wait.

Your situation is very dangerous. You need someone there to fix it RIGHT NOW. Pay the weekend rate if needed.

If you don't know a good steam man in your area, go to the Find a Contractor page of this site to locate one near you.

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Pete Novak

OK thanks. I'll go there today, and get it taken care of. What I'll immediately do is open all the other radiators, which should decrease pressure, then I'll adjust the gray shut off box all the way down. I remember it is a honeywelll unit, w/ a small linear slide, that looks like you could use it to adjust the thing. I'm not sure what it is set at, but I'll slide the lever all the way down.

Pete Novak

setting the pressure regulator

The honeywell unit on the system that I had seemed a bit strange to me. On the outside was a linear slide adjusted by a screw which seemed to adjust the cut in pressure. I took the cover off it and it had reostat (sp?) which adjusted the "differential". Then there was a formula that said " Cut out equals cut in plus differential". Why wouldn't that be easily accessable instead of concealed behind a cover? Anyways, I put my differential at one, and my cut-in at one, now it shuts off at two psi like it should. Thanks for your help!!

Steamhead

Glad you got to it in time

now watch the fuel bill go down. That's the usual Honeywell PA404A control. I suppose the differential wheel is inside because once the control is set properly it shouldn't need any further adjustment.

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