Boiler building pressure, HELP!!!!!

dann crist_2

the system worked for ten years---STEVE---since physics is constant, if the problem were the location of the PRV it would have happened long before now even though I agree that what you suggested can be problem, it's not likely the problem here

Russ

Boiler building pressure HELP!!!!

Just come from a customers house where the Hot Water
Baseboard boiler is building pressure past 30#. Now the system has been installed for ten years it has a indirect
waterheater & four other zones.Now part of the problem
is that the boiler has a XL100 T&P relief valve on it,
and no releif valve on the indirect.But why has it worked for 10 years until now.I got the call that the boiler was
blowing water & steam out the relief valve.Have already
checked the expansion tank & S1156F valve, the expansion tank, is piped off the half inch feed line on the return side, it has honeywell zone valves & a grunfos pump on the return side also.So my question is although the guy who installed it took major shortcuts why has it worked for ten years until now & what suggestions there are to remidy the problem it dont seem to build pressure until the pump kicks on

Big Ed_2

Bomb

You found a 100XL on the boiler and no relief on the indirect. What you have there is a homeowner's home made time bomb. I hope you set it right . Well the 100XL would not pop until 150# , so it's releasing under temperature now, which is 210* (I think) . I guess the boiler temperature never reached it until now.

dann crist_2

another subtle problem

is likely occurring, the core inside the indirect tank may have a leak, thereby allowing house, domestic water pressure to slowly increase the pressure in the boiler as the higher pressure in the domestic system overcomes the rather low pressure in the boiler. to test for this isolate the indirect coil ( hopfully the meathead who installed the system allowed for this to be done) The boiler should then maintain it's normal range. Tank replacement is the only solution to the pressure creeping up to above 30#

This occurs without other symptoms in tanks w/o a double wall coil common about ten years ago. the tanks w/ double wall coils simply leak onto the floor.

Steve Eayrs

How did you test the fill valve?

I have seen ones that worked fine, but because of the placement its tied into the system on the return, (before the pump?), would draw water in to the system when the pump kicked in. The age old vaccume problem.... May need to move the tee for boiler feed to another part of the system, (pressure side instead of vaccume), or better yet repipe the system pumping away, and change everything. I imagine that you have other potentual problems, that would be fixed in the process, if the guy was dumb enough to install a 100# relief vlv on the boiler.
Placement of pressure tank, and amount of pressure in it, could also contribute to the problem.
Steve