Question about Honeywell Programmable Thermostat Heater

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Honeywell RTH230B I've just replaced my old thermostat with a new honeywell RTH230B but it didn't work. I installed it exactly as the instructions guided. The fan is supposed to run when switching to 'ON' position but nothing run. My furnace is using gas. Please advise. Thank you so much.

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  • matkieng Feb 04, 2008

    Thank you so much for your advice. I did as you guided and finally I could make it! Both heater and A/C are working perfectly after burning 3 transformers :-) I am wondering why Honeywell did not put a simple advice like this in the User Guide Manual.

    Again, I greatly appreciate your help.

  • matkieng Feb 04, 2008

    Thank you so much for your advice. I did as you guided and finally I could make it! Both heater and A/C are working perfectly after burning 3 transformers :-) I am wondering why Honeywell did not put a simple advice like this in the User Guide Manual.
    Again, I greatly appreciate your help.

  • Anonymous Sep 05, 2008

    thermasat doesn't show digits or numbers

  • Mike_Schwin Oct 23, 2008

    I am replacing an old non-digital Honeywell dial thermostat with the Honeywell rth230b thermostat. I have Y- G- W- R- B wire coming out of the wall. On the old thermostat the blue wire was not used, it was wrapped up and tucked into the wall space. The rest of the wires when to their corresponding colors:

    Y = Y
    W = W

    G = G

    The red wire was stripped bare in two places and wrapped around both red (h & c) terminals.

    I put the red wire in the Rh and used the jumper provided to the Rc and connected the other wires to their corresponding colors. I put fully charged batteries in the unit and actually tried 2 sets. The only thing that I can get to work is the fan while in manual mode. The thermo shows the little flame and snowflake when switched in too heating and cooling modes but nothing happens. The furnace worked fine before the change.
    Any Ideas?



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Normally, you should have 5 color wires: W-White, Y-Yellow, G-Green, R-Red and C-Blue.

The Blue wire is a common from the transformer on older systems, which is probably hooked to RC terminal.

Try this: Remove the blue wire and jump the RC to RH with the red wire and you will be fine. Blue wire should not be needed with the new thermostat.

This should also be stated in the instruction manual.
Hope this helps.

Posted on Feb 03, 2008

  • Thank Oct 17, 2010

    Thank you so much. I was with out heat for for Three months. Not knowing what to do with that Blue wire. LMAO. I did not have the money to pay someone. I tell you, I feel so good in this house right now. LOL. Once again,Thank you so much. You the best.

  • Ruth West Sep 30, 2013

    Thank you! I've been trying to figure out what that blue wire is for!


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The MacGyver solution above worked PERFECTLY. The blue wire is not needed in older systems and the problem can be solved by using the red jump wire. Just place the red jump wire around the red RH wire and insert the other end in the RC terminal and it will work. Great Forum!!!!

Posted on Apr 06, 2010

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I have a similair problem with this controller. I have a 5 wire coming from my wall. 2 of which goes to heating which runs fine. The 3 wires (red, white, and green) should somehow go to cooling but thus far I can only turn the fan on and off. Any help??

Posted on Jul 01, 2008

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Posted on Jan 02, 2017

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SOURCE: thermostat won't keep furnace fan running

You probably have a loose or broken wire to the fan relay. Check the wires on the thermostat first. Pull up on the bottom of the thermostat to remove it from the wall plate. You should see several screw terminals and the conductor wires that should be connected to them when you look at the wall plate. Check if any of the wires are disconnected or broken. If a wire is broken, strip a portion of the unbroken section of the wire and secure it to the appropriate screw. (The fan relay terminal is G for most setups.) If none of the wires are loose or broken, then you have to check for damage to the wires between your heating system and the thermostat or at the heating system. It could be a bad wire going to the jumper on control board or damage to the board itself.

I hope this helps. If the problem is not at the thermostat, you may need to have a professional diagnose and fix the problem. However, if you post additional comments about your heating system, Fixya experts may be able to help you diagnose the problem.
Cindy Wells
(we had the broken wires at the thermostat keeping the fan from working in the past. It's an easy fix if you are willing to handle small wires carefully.)

Posted on Jul 06, 2013

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