Pressure Relief Valve Opens on Boiler

rbmcduffee

I have a Peerless residential boiler - model G-760-W-S - which the manufacturer no longer acknowledges. The 15 pound pressure relief valve blows about twenty minutes after boiler turns on. I replaced the valve last winter because of minor leakage - a drip, not open - and had no problems until initially calling for heat yesterday. The "Internal Syphon Compound" is stuck at 30 pounds on the pressure end of the scale. When I turn the boiler on and open the tank drain, the burner cuts off when about a quart of water has been removed - seems the float valve works. Burner comes back on promptly. "Cut In" is set at 0.5 pounds. (There's no cut out to which I have seen references in other posts.) The pressure relief valve closes in short order when the boiler is turned off. What could be causing such a problem? Is it likely that I have a bad pressure relief valve?

Separate Question: I'd like to buy one of Mr. Holohan's books - which one? (There are a lot of them.)

KC_Jones

SHUT IT DOWN NOW!!!! It is most likely doing it's job and you probably have a clogged pigtail on your pressuretrol. If so it isn't reading the boiler pressure and letting it get out of hand and you hit the safety. You have a dangerous situation and need to get it resolved immediately.
After you shut it down take some pictures of the boiler and we can point you in the right direction or tell us where you live and we may be able to recommend a steam pro to come help you out.

delta T

Agreed, a 15lb relief blowing means that the control on the boiler is not sensing the pressure and shutting the burner off when it should. Shut it off and get a pro out there imeadiately

delta T

The books on steam for you would most likely be 'We Got Steam Heat' and if you want some more detail and history 'The Lost Art of Steam Heating'.