I have been having some issues with the heater lately. First off I have a heat pump with backup gas furnace, and a/c. It seems that the fan continually runs. It also seems that the heat pump never runs even though I have the thermostat set to “heat” not “emer heat”. Also the fan seems to run almost all the time.

I smacked the thermostat the other with the ladder my mistake…so I kind of think the thermostat might be causing the issues. BTW…I just bought this house, so I am not familiar with how things have been working. I can just compare it to my old house which also had the same type of heating and cooling.

So…since I thought it might be the thermostat, I purchased a new one. I am replacing a Robertshaw programmable thermostat (model number 9620 I think) with a Honeywell RTH7500.

I notice in the installation manual that it states if the old thermostat had wires on W1, Y1, and W2 that some system modification is required. Does that mean if it had wires on all three, or just on one of them? And what modifications?

I’ve installed the new thermostat as the directions describe, I took Y1 to Y and W2 to E. I went through the setup of the thermostat and told it which heating system I had. Installer setup number 170, I told it I had #9 which is, multistage conventional heating and cooling, 2 stages of heat (wires on w and w2) and 1 stage of coolilng (wire on Y).

The problem I have currently is the only system options I get are “heat, off, and cool. I don’t have emer heat, as the manual describes I should have. Just for kicks I turned it to heat and cranked up the temp some. The fan kicks on, the furnace does not come on, and the heat pump does come on…I can hear a buzzing sound…but the compressor fan doesn’t run.

Current setup

Old new
R R
G G
O/B O/B
C C
Y1 Y
W2 Aux
E E


So…anyone with any suggestions? I have it on “off” for now.

Thanks!

I would be surprised to see a quick simple answer to this. It looks like you have several problems and some of them are outside my experience. Lets start with the gas furnace where I know the most. Does its controls have the R, W, Y, G, and B or C labels on the terminals? If so, try jumpering the R (hot from the thermostat) to W, heat. The gas burner should come on, and in a few minutes, after the air warms up the limit switch, the blower should come on at low speed. If you remove power from W, the blower should run a little until the limit switch cools off. If it doesn't work, check to see there is 24 volts between the R and the W. The R should have a red wire running to the transformer. The W should connect to the gas valve which should also have a blue wire running to the transformer. Some of the connections may be on a circuit board, harder to trace.

Next, jumper the R to G. The blower should start up at once at high speed and shut off when you remove the jumper. In either case, if the blower doesn't work right, likely the problem is a relay, again, often on the circuit board.

Now going to your thermostat. I am not sure what O/B does, perhaps switching the heat pump between heat and cooling, It looks like E signals the heat pump to produce heat, and W2/aux for the gas furnace. Y/Y1 is for cooling, and C is the opposite terminal of the transformer from R. I don't know how the system is supposed to select the heat pump or other heat. What does the directions say?

If you go to https://www.askmehelpdesk.com/showthread.php?t=15608, you will see I didn't give much better of an answer to a similar question. Perhaps among the 3 of us, we can get this figured out. Questions like this keep coming up, and I am sorry I am not able to give good answers.