New Thermostat/Old Boiler

Old 10-05-05, 05:48 PM
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New Thermostat/Old Boiler


Some advice if folks don't mind. I'm trying to install a new thermostat with programming ability, and basically, I don't want to mess up my 1950s circa boiler, just yet. (new home owner and money is tight).

There are 4 wires coming from the basement. red/black from the transformer, and white/green (which are spliced back into white/black in the basement) that go to the furnace. The system is 12v A/C (from r/bl). I need to which wires go to to which screw on the new thermostat (White-Rodgers 1F80-261). My options are: RH RC W B C G O Y. I'm pretty sure that Red from transformer goes to RH. White goes to W and Black goes to C (I think common ground). That leaves me with a Green(Black) that goes to the furnace, but I'm not sure where that goes.

Any help would be greatly, greatly appreciated. My furnance guy refuses to work in my new town (from burbs into city) because of Inspector graft problems.

Old 10-06-05, 04:41 PM
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4 wires

I've never seen a thermostat for heat only which used 4 wires. To what do these 4 wires connect? What terminals were they hooked to on the old thermostat? You should have 24VAC between at least two wires.

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