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https://www.askmehelpdesk.com/showthread.php?p=55945#post55945

The thermostat is simply a multiple pole switch. Depending on the mode, it switches power from the transformer, red, R, to W, Y, or G. When the heat or cooling reaches the set point, it switches to off. If the heat quit when the old thermostat shut the power to W off, it should when the new one does too. Does the furnace have a B or C terminal? One of the pair of wires out to the A/C compressor should be connected to it. If you have 24 volts AC between the W and B or C when the temperature at the thermostat is above the set point, the thermostat is definitely not working correctly.

I don't know why the blue is connected to the Y instead of yellow, but as long as you have the same wire connected to the Y at both the thermostat and furnace, the A/C should work. Electricity can't tell what color the insulation is.

I just purchased this thermostat and am trying to install 2-wire heat only.

I have a WHITE wire from furnace, carrying 28 volts, and a RED wire with no voltage.

I hooked up WHITE to RH, and RED to W per instructions. Wire connecting RH to RC was removed as per instructions. Other jumber (HE HG) was not touched).


I get no switching when I set the thermostat. Can I take it off the wall, disconnect it, adjust the temps and test with a multimeter? Any other ideas?

Thanks in advance.

The red and white wires are reversed at the furnace. The red should be power from the transformer and the white connect to the gas valve. Any time the red and white, reversed or not, are connected one way or another, power should flow to the gas valve and other components needed for a heat cycle.

For the thermostat to draw power from the furnace, the wire from the transformer, usually red, should be connected to both the RH and RC. The thermostat itself also needs some connection back to the common side of the transformer to use power from it.

The thermostat also has a battery. Somebody reported success replacing the battery. With the battery powering thethermostat, what you did should work. Simply connecting the red and white, should start a heat cycle and continue as long as they are connected.



There are several threads here where people are having trouble with that thermostat. My instructions, that work with most thermostats, are not fixing the problem. Somebody needs to find some instructions for the thing and post them here. I have helped people figure out a number of problems, but am getting nowhere with the RTH230B

I also think this thread should have been left in heating and cooling where the others on this thermostat are. This is clearly a HVAC issue.

Please do not shoot the piano player. He is playing the best he can.

Thanks labman. Perhaps there is a general problem w/ this thermostat. I'll call Honeywell and see if they have any answers. If so, I'll post here.

Thank you so much for your help labman. Replaced the batteries, and now it works just fine.

IF LOW BATTERY LIGHT IS SHOWING, THERMOSTAT WILL NOT SWITCH HEAT OR COOLING ON!

I blame Honeywell for not including a note about this in their instructions. It would have saved me several hours of guessing, testing etc.

If you have a minute labman, perhaps you can contact Honeywell and suggest they include a sentence in their instruction manual that tells people the thing won't work if batteries are low (I contacted them, but it may mean more coming from you).

Thank you so much for your help, your advice saved me hours of headache.

Best Wishes,
Elahu Gosney

Honeywell can be contacted here:

http://www.honeywell.com/sites/portal?smap=honeywell&page=customeracs&theme=T9&c=n&BU=Solutions%20for%20Homes&SBU=Thermostats&[email protected]&web=http://content.honeywell.com/yourhome/ptc-thermostats/thermostat.htm