My programmable digital Thermostat stopped functioning properly all of a sudden. It had been working fine when set on AUTO. The heat would kick on when it reached the preset temperature. However, the Thermostat no longer allows me to set a temperature while on AUTO setting.

The only way the heat will come on now is if it is set to FAN ON. The heat will come on but needs to be shut off manually in this setting.

I do not know why this stopped working all of a sudden. I assume it is because of the Thermostat. I even replaced the 357A button battery but the problem remains.

The wiring coming out of the wall has two wires: Red and White. Thermostat has RC, RH, Y, W, G.
It is currently wired from the wall to the Thermostat like so:
Red Wire into W (on thermostat)
White wire into G (on thermostat)

Is this correct? Should it be Red into R and White into W? If this is wrong, why would it work fine for the past two winters and stop working all of a sudden? Should the Thermostat be replaced? How would it need to be wired?

The existing Thermostat is an Invensys with #0541R stamped on the back plate. I could not find any info on this model anywhere.

Any help or thoughts would be appreciated.

Thanks.

 

Invensys is a Robertshaw brand or vice versa.

I can't be sure unless you check on the furnace connections but the standard color code is that R (red) is power and W (white) is heat. G (green) is the blower in a forced air system and Y (yellow) is cooling.

So if the colors are connected correctly at the furnace then the red wire from the wall is connected to RH on the thermostat and there may be a "jumper" wire to RC. For a heating only application the jumper is not needed, yet does no harm.

The white wire from the wall is connected to W on the thermostat.

With your wires connected to W and G the circuit would be closed whenever the On-Fan-Auto switch was shifted to On. It is possible that if your thermostat has a gas-oil / electric heat selector (it would be on the inside of the thermostat) and if it were in the electric position it might work (more or less) with the wiring configuration you had.

So reconnect the red wire to R and the white wire to W and test it out. If it now works okay then sit back and enjoy the warmth. If it doesn't work we will move on to step two.

 

Thanks for the response.

There is a jumper wire from RC to RH.

I switched the wires so Red goes to R, and White goes to W. It did not work. Nothing happened and the heat would not come on using AUTO or FAN ON.

I have switched the wires back to the way they were before (Red - W, White - G) so the heat could still be turned on using FAN ON.

I thought it was wired incorecctly also but as i said, it had always worked without any problems. So, still working on this...

 

Did you leave or diconnect the jumper when you inserted red wire? Just minutes ago I installed new digital stat and had to leave in the jumper, as the old stat was wired that way, also. This house has features of: furnace heat, plus you can run the blower on "on" or "auto", and has central a/c. Only had 4 thermostat wires. (and the jumper wire already in the stat, on both the old and new one, between Rh and Rc)

 

I left the jumper wire in place.

Also, the Thermostat does not allow you to even preset the temperature in AUTO setting. The set temperature on the display does not change when using arrows to set while in AUTO.

This with the fact that it stopped working at all in AUTO is making me think it is a problem with the Thermostat.

 

If the battery you replaced with is good then the thermostat is toast.

 

Did you hold the arrow key in long enough for it to record as "set"? On some models you have to hold arrow key for a few seconds before it changes from the room temperature to the ability to change the "set" temp.

As far as the batteries go, did you inspect the terminals the batteries go against? Today mine were corroded with that battery acid froth stuff, and I cleaned mine up with baking soda-water-toothbrush.

No internal dip switches got bumped/changed position did they?

 

It wasnt a problem with setting the thermostat. I had been using it for some time.

I wound up buying a new thermostat - Honeywell. Wired the Red to the RH and the White to the W. Removed the jumper from the RH and RC as stated in the instructions.

Everything is now working properly again with the new Thermostat. It just seems that the old one died on me.

Thanks for the repsonses and help.

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