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Primary/Secondary zone differential bypass valve
Recently had a new gas boiler (GV90+) installed, including all new zone controls. Heat is baseboard hot water running 3 zones plus DHW, all using zone valves and the primary circulator pump in the boiler. Control is using a Taco 4 zone controller with priority. Everything seems to be setup and sized appropriately. One part of the install that looks wrong to me is the system is setup with a primary/secondary loop. (I think i have the terminology correct) The primary loop feeds directly back to the boiler (using 3/4 pipe which matches the zones, 1" feed/return lines). I understand primary/secondary is normal, but since the system is using zone valves instead of circulators it looks like there should be a differential pressure bypass valve, but instead the installer put a ball valve in the secondary loop and suggested putting it in a partially closed position. I asked him about it and he said something to the effect that it's not really needed and he likes to use as few parts that could fail as possible. How wrong is this setup, and how much could it be hurting my efficiency? The boiler does seem to short-cycle quite a bit, (on for 3-5 minutes, off for 3-5 minutes even when the two larger zones are calling for heat, and i'm wondering how much the incorrect primary loop is contributing to this. I'm going to start measuring return temps with the valve closed and partially open to see how much of an impact it has. Also, the boiler already has a secondary pump to protect the heat exchanger, so is a primary/secondary loop even necessary?