Pressure rising to 60psi

Steve Garson_2

I had to replace a leaking expansion tank last week on a radiant heating system. I installed a new one with a 20psi charge and charged the system to 20psi. The water-feed valve was then shut off.



A few days later, I saw the pressure gauge reading of 60psi. Puzzled, I drained around 2+ quarts of water and the pressure went back down to 20psi.



Today, the pressure was high again, so I drained some more. The water temp varies from 100* to 140*.



This all seems wrong. What is happening here?



Thanks,



Steve Garson

Boston, MA

Jean-David Beyer

What is happening here?

Indirect domestic hot water heat exchanger leaking domestic pressure into boiler circuit?

Steve Whitbeck

20 PSI

If this is a standard 30 PSI max pressure boiler the tank should have a precharge of 12 PSI.

And the most important question is WHY didn't your relief valve trip. If is has a 30 set point it should have tripped. Replace it NOW.

As far as the pressure gain IF you don't have an indirect domestic water heater ( hole in coil is pushing water into the boiler system ) Then the pressure reducing valve is bad and the shut off valve is letting water leak into the boiler. replace both.

unclejohn

You may

Simply have a faulty pressure gauge. Relief was not opening? Was the old tank a extrol tank or the old style. And as in previous post why the 20psi charge? Did you connect the new tank in the same location as the old?

heatpro02920

What kind of system?

radiant with a cast iron oil fired boiler with a tankless water heater for dhw? Gas with an indirect, oil with an indirect, a high pressure tankless with a plate exchanger, ect??? need more info, like was mentioned a boiler with a psi reducing valve and a extrol 30 expansion tank shouldn't be anywhere near 60 with out water pouring from teh pressure relief valve...

Steve Garson_2

More info

The "boiler" is a Bradford-White Combicore water heater.  The expansion tank was and Extrol tank that leaked and replaced with a new one with a 20psi charge. The feed water valve has been shut off, so the additional pressure must be coming from a leak in the coil, with city water coming in gradually, to the tune of 5psi a day recently.



I need to replace this with something that will last more than five years.  My steam boilers heats a 10,000BTU heat loss hot water loop,  The Combicore heats a 15,000BTU heat loss radiant heated room.  The Combicore has 65,000BTU input. So I will need a boiler to output the combined 25,000 BTU for heating, as well a 45-gallon indirect hot-water tank.



Any boiler recommendations?  The BTU requirements are so low that I don't think a condensing boiler would ever be cost effective, since I will not be in this house longer than five to ten years, at most.



Steve