Pressure in Steam Heating System

Ryan_16

Hello-
My house has steam heat, 6 radiators on two floors.
I have an 8 year old gas fired Burnham independence boiler.
The boiler runs for about 20-30 minutes at a time, which seems about right, and it is rare I have to add water.
I replaced most of the valves last year with good ones from the supply store, had the furnace cleaned by our local plumber this year, and drained it recently and filled it with new water.

That said, the boiler has very confusing pressure readings, which may or may not indicate a problem.
The boiler runs till the internal syphon gauge shows a PSI of 9. If it gets above that the furnace cuts out. However the Pressuretrol is set at 2 PSI.

My basic questions are:
How could the boiler get to 9PSI without steam shooting out of valves?
How is such a large discrepancy possible between the internal syphone gauge and the pressuretrol?
Could the syphon gauge be out of whack?
Could there be a clog in the internal boiler somewhere?

Apologies if these are dumb questions, but I want to understand the problem a bit better before I call the professionals in.

Thanks
Ryan

Brad White_203

Good Questions-

I suspect that if there is an internal siphon, (any siphon for that matter) it is probably clogged.

As for steam shooting out of valves, if you mean the pressure relief valve, that is set by code at 15 PSI.

Your system should probably run on one pound or less.

Those are hardly dumb questions and I for one am glad you asked. Safety is involved.

Dale

strange pressure

I too think the pigtail is plugged, also set at 2psi could mean different things if you have an additive differential type control or a subtractive type. The common old pa404a from honeywell is additive in that the off setting is added from the on and the differential. Besides changing the pigtail, I like to just put a water hose adapter to the bottom water drain valve outlet and run a clear hose up to the ceiling joist. Mark the off or normal water level, 28 inches up from that is one pound, another 28 (56 total) is 2 pounds which should not be exceeded as an off pressure. This is a cheap and very accurate check of gauges. good luck

Ryan_16

Yeah, the pigtail being clogged would make sense. When I first bought the house I pressurized the system, so some water and gunk might have gotten in there.

I'll try the hose trick as well, that sounds like a good idea.

Thanks for the help.
Ryan

Fred Harwood_2

Clear hose

Dale, I've used that clear hose trick to verify pressure for years. It's simple and cheap, and very, very accurate. Especially good for verifying Vaporstat settings.

Also, I use it to monitor small pressure changes as the steam arrives at the main vent, a large radiator, etc. Provides another window into the system.

rich on heat

Hose "pressure meter" a great idea!

My boiler's pigtail was all crudded up and pitted. Got a new bronze (red brass) one from Mc Master Carr
http://www.mcmaster.com/
Type "pigtail" in Find Products space.

Unknown

aarrrghh not another one

Never knew that "furance" have pig tail!! I thought only BOILERS have them....