Zone getting heat constantly
I have a boiler with 5 heating zones. I currently have one zone that is getting heat pretty much constantly even with the thermostat off and pulled off the mounting plate.
I assumed it was a bad zone control valve and replaced the power head (Honeywell) that power head was definitely bad. The power head I replaced it with should be good but was removed last winter chasing another issue. I have another power head on the way but it won’t be here til Monday.
I was able to test all 5 zones and it sounds like everything is opening correctly when being called for heat. I have replaced the thermostat with brand new one and tested it with the other zones as well. Could I have wired the zone valve wrong? The wiring is sort of a rats nest. What else should I be checking to rule out?
I recently replaced the expansion tank, purge valve and backflow preventer. Those shouldn’t effect this issue just some extra info.
Comments
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"Could I have wired the zone valve wrong?" Most Likely. If the lever under the wire connections moves freely without resistance when the thermostat for that valve is off and another zone is calling for heat, yes.
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I had my wife turn each zone on and made sure each zone valve was opening independently. I will recheck it again today but it didn’t appear to be opening with any other zone.
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Why is the pump running and boiler firing when there is not a call for heat? Have you verified that the zone valve in question is closed when the thermostat is not calling for heat? The guts in those Honeywell ZV is a rubber ball on an arm that essentially rolls over to block the hole, rather than an actual ball valve like a Sentry. Those balls can and do wear out/fall apart so regardless of whether the head is doing its job, if the guts are shot, it'll still flow when the circulator is running
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Is it a 4 wire zone valve? If so remove all the wires from that zone valve, that will assure it is closed. If flow is still moving to that zone, the valve mechanism may be bad. What size circulator do you have?
Assuming this is a spring return type of HW zone valve. A pic would help see exactly what you have.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
I don’t believe the boiler is firing just constantly pushing heat thru that zone. What is the best way to tell if that rubber piece is shot? Starting to think that might be my issue.
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I’ll get some pictures later today but it is a 4 wire zone.
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I unwired the power head and found water still flowing. I have some spare valves from all the power heads I’ve replaced over the years. It looks like I can steal the guts from one and replace it without sweating a new valve on.
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Why is the circulator running when there is no call for heat? That's more important than the zone valve but yes you can rebuild the valve without swapping the body.
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Maybe gravity feeding from boiler; does it have aquastat controlled tank?
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It’s only happening when other zones are calling. I found that out when testing this morning.
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