[marklar]

OK, I have an old thermostat that needs to be replaced. Just to be thorough, the old thermostat is a Goodman mod #HPTD18-60. It's a 24v line that controls both heating and cooling and has a multistage heat pump.

The new thermostat is a honeywell RTH7400D. The old thermostat uses the following wires:

Y, COM, R, G, W2, E/W3, O, B

The new thermostat uses R, O/B, Y, G, C, L, E, AUX.

The problem is that the O and B on the new theromstat are on the same connection. It says that if the old thermostat had both an O and B wire then I need to contact honeywell. I did that and got no help. They just said to call someone to install it.

Where should all the old wire go in the new thermostat?

I don't want to spend a service call fee for soething that should not be this hard to install.

Thanks for any advise.

[labman]

If you didn't get any instructions on the functions of the contacts of the thermostat, I would go back to where you bought it. If they can't help, ask for your money back. I think for what you pay for the more complex thermostats, you are entitled to at least a list of the terminals and their functions.