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I cleaned up my wiring and installed a Taco 403-4 zone valve control. I have kind of a different system that was wired by a contractor that has left my area. There are 4 zones. 1 zone heats a baseboard zone on the lower level, one zone heats a baseboard zone on the upper level, one zone heats the lower level floor with radiant and 1 zone is for the domestic hot water. The previous wiring operation opened the radiant floor valve whenever one or the other or both of the two heating zones opened. I'm trying to figure out how to make the radiant zone open without adding a t-stat. This system worked great for years but it was set up with a priority relay for the domestic and on really cold days the house would get cold when the lovely bride would do laundry all day. It's a small house so running the hot water and heat at the same time isn't a big deal. what started the whole change out was a bad motor on the radiant zone valve, I just blocked it open for winter (warm floors are nice in Colorado in the winter!) but I want to get some control back. Zone valves are Honeywell V8043E1012. I wired the 2 baseboard zones and the hot water zone per Taco's diagram and they all work great. I just need to open (and close) the radiant zone whenever a heat zone calls for heat. Any help would be appreciated.