Help! Pressure rising after adding water

ChrisCS

Help! I recently bled water from my hydronic heating system, and then added some water to get the pressure at 15 psi. The syatem is off, not circulating. Now, pressure has risen to 20 psi in 2 hours. Is this a problem, or is the water preaaure just balancing itself out?

Jamie Hall

This is a problem, and my bet would be that the valve which you used to add water isn't shutting off tightly.

hot_rod

did you check the expansion tank? If it is waterlogged pressure will build as the water is heated.

ChrisCS

New expansion tank. So it isn't that... and the system is off.

Any "easy" way to replace the fill valve haha....?

EBEBRATT-Ed

The PRV fill valve probably hasen't been used much and when you added water it opened and now will not reseat. Just shut the manual valve that feeds the PRV until you can replace it.

hot_rod

Is there a domestic hot water device connected? An indirect tank, plate HX or tankless coil? Pressure can cross over in any of those applications. It may creep up high enough to cause the relief valve to discharge. Has the relief valve been changed? Accurate pressure gauge on the system?

Even an old isolation valve on a boiler fill valve can leak if infrequently used. Only a physical disconnection could tell that with 100% certainty. Is there a union on either end of the fill valve? Is there a backflow device installed with the fill valve?