Increase in pressure in Oil Burner

I have a Burnham V7 that was replaced in 2003, due to bad casting. It's a hydronic system with the Oil burner circulating hot water to the water heater. The system has 3 zones, plus priority for Hot water. The main 30Lb pressure relief on top of the burner started leaking about a week ago, I replaced the relief valve, and turned on the burner, the hot water started calling for heat, when the system got to 205 degrees, the pressure was at 31 or 32 lbs the relief valve started to drip. I'm wondering why the internal pressure is up to 31 or 32, during the winter it's running 8 hours a day and no leakage, pressure was 29 or 30. What could be causing an increase in pressure.
Thanks
Gregory

 

sounds like your high limit is too high (should be ~180F), for one. runaway pressure could be a blown expansion tank diaphragm aka waterlogged expansion tank. search the forum and you'll find the procedures for checking this stuff. normal system pressure should be around 12-15 psig. good luck.

 

I just checked the expansion tank it has 0 air pressure, it has a stated max of 12 psi, I will try to pump some air into it in the morning.

 

The tank could have just leaked air but this is rare. Most likely the tank needs to be replaced. If the installer was thoughtful enough to install a valve between the tank & boiler, this change out is a simple job.

 

I put 12lbs in and it's holding, I may have released it when I was checking the pressure and cleaning the relief on the top of the tank. We will see how it holds.
Thanks
Gregory

 

The oil burners pressur has not gone past 15 or 16, that with it running thru one of my wifes 30 minute showers, on and off for 10 to 15 minutes. Looks good. Thanks for the help and excellent advice.
Greg

 

Sounds like you have it fixed. Good job. If it holds for a couple of weeks you should be in good shape.