Relief Valve dripping and rellieving.

Jon33

I have a oil fired, forced hot water system with a storage tank as one zone for domestic hot water.  The relief vale would let water out most in morning with a slow drip otherwise.  First off the fastfill combo and the relief were replaced...to no avail.  Next I replaced the expansion tank.  This corrected the problem for about two weeks.  It started doing the same thing.  I replaced the relief valve at this point, hoping maybe it had gotten gummed up in the process.  This fixed the problem for about 3 days.  Now it has returned.  I am wondering if it is a problem related to the storage tank or boiler.  Any suggestions to try on either end would be appreciated.

Paul Fredricks_3

assume

I assume you are talking about the relief valve on the boiler, not on the storage tank.



It's very possible that the coil in the storage tank is leaking very slowly, raising the boiler pressure. The only way to be sure is to turn off the boiler and shut the valves to the storage tank, from the boiler, so that it is isolated from the boiler. Then watch the gauge on the boiler. A slow leak may take quite a while for the pressure to rise.

EddieG

Also..

As Paul stated it could be in the tank. What is the system pressure running at when the boiler is around 180 degrees? What was the expansion tank air pressure before it was hooked up to system? Where is the fill piped into the system? Where is the circulator(s) located in the system?