Hey all-
Attached is a one-line schematic which depicts the hydronic loop for our home's heating system. Hot water is supplied to two Unico AHU's, one per floor.
At the end of last heating season, the pump for the 2nd floor started leaking like crazy and according to the original installer, a new pump replacement alone (minus the motor) would cost more than a new cartridge pump (the old pump was a big B&G series 100 pump which according to a number of sources was grossly oversized anyway). I bought a new pump and flanges and replumbed the manifold, replacing all of the old black pipe with copper. I then purged all of the air from both zones using the fast-fill lever on the pressure reducing valve (a B&G). The system worked perfectly and there was zero air noise in the lines running to the second floor.
Fast forward to the current heating season. I noticed that there was again noise in the 2nd floor supply line. Further, my wife called me at work to report that water had come from the boiler relief valve discharge line. Here is what I noticed.
In the sketch, there is a combination pressure/temperature gauge on the boiler water inlet. When the system is idle (no call for heat from either zone), the gauge reads zero PSI. Since the outlet of the make-up PRV is connected to the boiler inlet, logic would tell me that it should always be registering a pressure equal to that of the PRV setpoint, i.e. 12PSI. Is this correct? I isolated the valve, made sure that the strainer was clean and verified that it passed water when valved in (although I did so by operating the fast-fill lever only).
Based on the fact that pressure gauge reads zero when the system is not running, is that in itself indicative of a bad PRV? If the system pressure drops below setpoint, one would assume that the PRV would attempt to raise the pressure. If the PRV is indeed not working, would one expect that it may lead to the system developing air in the lines? I was under the impression that the air scoop was responsible for removing trapped air in the system.
If any of you can offer any advice, I'd appreciate it!
Thanks,
Jimmy
Attached is a one-line schematic which depicts the hydronic loop for our home's heating system. Hot water is supplied to two Unico AHU's, one per floor.
At the end of last heating season, the pump for the 2nd floor started leaking like crazy and according to the original installer, a new pump replacement alone (minus the motor) would cost more than a new cartridge pump (the old pump was a big B&G series 100 pump which according to a number of sources was grossly oversized anyway). I bought a new pump and flanges and replumbed the manifold, replacing all of the old black pipe with copper. I then purged all of the air from both zones using the fast-fill lever on the pressure reducing valve (a B&G). The system worked perfectly and there was zero air noise in the lines running to the second floor.
Fast forward to the current heating season. I noticed that there was again noise in the 2nd floor supply line. Further, my wife called me at work to report that water had come from the boiler relief valve discharge line. Here is what I noticed.
In the sketch, there is a combination pressure/temperature gauge on the boiler water inlet. When the system is idle (no call for heat from either zone), the gauge reads zero PSI. Since the outlet of the make-up PRV is connected to the boiler inlet, logic would tell me that it should always be registering a pressure equal to that of the PRV setpoint, i.e. 12PSI. Is this correct? I isolated the valve, made sure that the strainer was clean and verified that it passed water when valved in (although I did so by operating the fast-fill lever only).
Based on the fact that pressure gauge reads zero when the system is not running, is that in itself indicative of a bad PRV? If the system pressure drops below setpoint, one would assume that the PRV would attempt to raise the pressure. If the PRV is indeed not working, would one expect that it may lead to the system developing air in the lines? I was under the impression that the air scoop was responsible for removing trapped air in the system.
If any of you can offer any advice, I'd appreciate it!
Thanks,
Jimmy
