Hi
We are trying to install a new honeywell themostat model rth230b.
Our old one is a trane baystat240 model 3aat80b1a1 problem being seven wires with no clue what colors or letters are for what?? The new thermostat seems to have five wires can this connection work and do you know the diagram or instruction on this installation??

Regards,
Shaun

This Honeywell stat is basically a 4 wire stat for heating and cooling only, the fifth wire is only if the cooling has it's own control circuit.

I attached the wiring diagrams for this stat, which you will find in the instructions.

With the seven wires you have on the old stat, sounds like you have a heat pump system, which this stat will not operate.

If not, best you can do is open the heating and/or cooling cabinet to see if there is a control wiring diagram to learn what the seven wires are for. Trane wiring diagrams are rarely available on the net.

If you are not sure if you have a heat pump, that is covered in a sticky in the Heat and Air Conditioning forum, https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313.html#post268231

We were fortunate to have Northern Heat join us last fall just in time for the flood of furnace questions. He is sharing his extensive HVAC experience including a fine sticky that answers many questions.

We now have excellent people in plumbing, heating, and electrical. I am happy to leave most of the questions to the forum expert. Unfortunately a few others don't. I only answered here todirect you to the sticky.