Still high pressure on boiler

Tony_17

I have a hot water boiler with radiators. 2 pipes - Hot water going out, cool coming back in with a B&G pump. The house has two floors above the basement.
My B&G relief valve was coughing up about a gallon of water in the morning and night when the heat came on. The pressure gauge on the boiler read 30 psi. So we replaced the expansion tank and the unit that has both the pressure reducing valve and the pressure relief valve.
I think it should stay at 12 psi but it's more like 15 psi during the off time. When I checked it this morning it was high again, around 25-27 psi. What else could be causing the high pressure or how do I diagnose where the problem is?

Thanks for any help you can give!

Tony

Uni R

The big two...

This could be caused by air or water. If air is in your branches you need to bleed it out. This would cause high pressure readings. "Pumping away" will help to prevent this. The other thing would be a faulty automatic water feed. If you have a low water cut off you should leave it the feed shut off. If it is not functioning correctly it could be allowing too much water into your system at closer to street pressure than you want. Turn it off and monitor the system for a while.

Tony_17

Air or water

We bled radiators but one since we couldn't get to the valve on it. Perhaps I'll have to remove the woodwork around it to bleed it.

I had 100+ psi coming into the house so we put a pressure reducer on there as well. When I checked the water pressure today, it is around 60 psi. To test if water is the problem, should I turn off the water at the shut off valve right before the pressure reducing valve for the boiler which is supposed to reduce it to 12 psi? Once I've done that, how and when should I monitor and what am I looking for?

Once again - Thanks!

Uni R

Air or water

How are your radiators piped? Look at http://www.heatinghelp.com/heating_qa.cfm if you don't understand my question.


Yes the valve leading in to or from your the 12# prv, whichever your case my be. I'd give it a day, but check often in case your system has a leak and has been getting make up water and a regular basis. You don't want your boiler dry firing.

Tony_17

Diverter-Tee Hot-Water Heating

I believe it's the Diverter-Tee Hot-Water Heating system. I've turned off the water valve going into the system and will keep an eye on the system. Shall I be watching for pressure changes? The pressure usually goes up in the evening when the thermostat is set to go up.

Uni R

Pressure

Yes, watch that it doesn't get too low. If it drops under 10# you know you have a leak.


If the branches are all completely bled, then the only other culrpit is that the tank has capacity issues (perhaps too small for the water content and temperature rise).


BTW, my system is 12# cold and 20# hot.