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Extra zone coming on with priority DHW
Hi all, I'm not sure if our Taco ZVC 406 is fritzing out or what. Whenever our DHW (zone 6, priority on) calls, our zone 4 comes on. The box is 19 years-old but nothing has changed with it in terms or wiring or anyone doing anything with it or to it. I just happened to notice both zones on one warm day, so I tested it and sure enough, zone 4 calls whenever zone 6 calls. It appears as if zone 6 is causing zone 4 to call. Anyone ever seen something like this? Do I need to get a new Taco unit?
Thank you very much in advance,