Internal Syphon Gauge Maxed Out

GuyWithPuns

Hello, I have a one pipe steam system. I just went to start it up for the winter and as it kicked on and ran for 20 minutes or so the gauge that reads "Internal Syphon" climbed up to, then exceeded, its max rating of 30 psi. I shut my thermostat off so that it would stop calling for heat. What's going on? What can I do about it? Is this something I need the boiler serviced to address? Thank you for any help you can provide.

I called my steam company and got some useless AI secretary. It eventually forwarded my message to the office but I'm in a cold house until I figure this out. Thankfully it's still in the 50's but I would like to do something about it soon.

mattmia2

you can get a gauge with a hose thread from a hardware store and screw it on to one of the drains on the boiler, open the drain, fire the boiler, see what the gauge reads. If the gauge on the boiler gets clogged with water trapped inside, as that water heats it will build pressure in the gauge. most likely the problem is with the gauge rather than the boiler.

bburd

If the steam pressure rose above 15 psig the safety relief valve should have opened. Maybe the gauge is faulty, maybe it's not. If the gauge is accurate and the safety valve failed to open, that boiler could blow up your house and scald or kill people. Leave it turned off until a qualified professional can assure you that it is safe to run.

Jamie Hall

Well… two rather diverging comments. Both of which I agree with — to a point. I'd go with @mattmia2 's suggestion, though — it can't hurt and is cheap and quick. @bburd is quite right — if the gauge is accurate, you do have a problem — so I'd only fire the boiler when I was right there to keep an eye on my temporary hose bibb gauge and shut it off if things got wild. the reason I am inclined to go with @mattmia2 , though is that you would have to have two independent failures for the gauge reading to be accurate (Maybe three for some boilers): the pressuretrol would have to have failed closed, and the safety valve would also have to have failed closed. Further — not a failure really — the vents would have been shrieking at you…

STEAM DOCTOR

I would bet my boots that the pressure did not rise to 30 PSI in 20 minutes. I would be surprised if it even got to one psi. That pressure gauge is almost certainly faulty

GuyWithPuns

Got a gauge and hooked it up. Opened the valve and fired the furnace. The needle didn't really move. I ran it for a while with no problems. The service guy came out and confirmed that everything was fine and that it was just a problem with the gauge. Thank you everyone for your help.