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View Full Version : RTH221B Thermostat. Heat won't stop running


jasongardner9
Sep 13, 2009, 06:18 AM
I have wired it correctly, actually wired it, then rewired it after my furnace wouldn't stop running. I have looked online and through the manual and all indications are that it is hooked up properly. White wire to "y", Red wire to "RH" with jumper to "RC", and the Blue wire to "W".
We have an oil burning furnace with baseboard heat. We keep the furnace off in the summer so we don't waste oil heating hot water all day. As soon as we turn it on to heat the water, heat comes pouring out of the baseboards and won't stop until we turn it off. I even have the thermostat in the "off" position instead of "Heat" or "Cool". The heat will come out until I turn the furnace back off, even if it is for 12 hours and its 80 degrees in the house, it just keeps running.

Any ideas on what I am doing wrong and how to fix it?

wmproop
Sep 13, 2009, 08:32 AM
If you go to the other end at the furnace where the tstat wires are connected, make note of what color wire is connected to which post, with the power turned off disconnect the tstat wires. Then turn power back on,if the furnace still comes on and runs,you will know you probably have a stuck relay,, if it doesn`t come on or try to run you will know it is in the controls meaning a shorted tstat wire crossed wire,or a bad tstat which controls the furnace


In most cases the rule of thumb is the white tstat wire should go to w,, the red wire to RH. You didn`t say anything about a wire controlling the fan, or anything about if you had aircondition tied to the furnace

If you don`t have air you don`t need the jumper from rh to rc

hvac1000
Sep 13, 2009, 08:45 AM
I think they have a boiler with a hot water domestic coil

jasongardner9
Sep 13, 2009, 08:51 AM
I just disconnected the jumper and it seems to have solved my problem.

No A/C.

wmproop
Sep 13, 2009, 10:08 AM
Great, glad its OK now