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shadow82399 09-20-2009 10:57 AM

3 wire thermostat
I am trying to replace a broken thermostat. It is a 3 wire White Rogers, one of three zones to a hot water boiler heating system. One wire is red, one is blue, and the last is white. Every thermostat (programmable) I buy has slots for 4 wires. Can I leave a slot open? I don't have a cooling system.

SKIP4661 09-20-2009 03:29 PM

For a three wire zone valve, the stat needs to have a contact that closes when when the call for heat is complete. The zone valves power open with a call for heat and power closed when the call for heat is satisfied. The average 4 wire digital heat and cool stat will not work for this application. There are some that will accomplish this but are usually more high end.

shadow82399 09-20-2009 04:30 PM

So what can I replace the thermostat with? One is completely shot, the others are just really old and I would like them updated.

beenthere 09-20-2009 07:37 PM

White Rodgers has stats that you can use. Don't remember the mod numbers off hand.
You may want to search their website.

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