How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Sean Your Own Question
Sean, HVAC Technician
Category: HVAC
Satisfied Customers: 194
Experience:  Owner HVAC company
Type Your HVAC Question Here...
Sean is online now
A new question is answered every 9 seconds

I had a honeywell t stats go out. bought a new wifi stat.

Customer Question

i had a honeywell t stats go out. bought a new wifi stat. honeywell also. the equiment i have is as follows: trane compressor XR15, Trane furnace heatpump with gas backup XB80 model tue080a948l3. the furnace has five wires to connect to, so i also have a honeywell interface module thm5421c, i guess this is to make the connections work for older furnace unit? the new stat is rth8580wf1007. i need to know if they are compatible, if so i need to know how to wire the stat, the module and the furnace
JA: Thanks. Can you give me any more details about your issue?
Customer: well like what?? that was pretty comprehensive
JA: OK got it. Last thing — HVAC Technicians generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: HVAC
Expert:  Sean replied 1 year ago.
Ill check into this and see if I can help
Expert:  Sean replied 1 year ago.

I looked into this, What is full model number THM5421C1008/U ??? is that it?

IF it is, The thermostat you purchased will not work and you will need to get the thermostat that matches that equipment which is TH9421 VisionPRO IAQ Thermostat

How many wires do you have at that the thermostat now?

Customer: replied 1 year ago.
the module just shows thm5421c, i have 5 wires there now, the heat works but only the gas, NOT the heatpump (compressor not coming on)so the module is to connect the newer xr15 compressor to the older furnace i guess. so is there another option besides the module, can it b e bypassed? if not then i guess i have to spend the big bucks on the correct stat. if that is the only option, do you know the wriing diagram then for the module?
Expert:  Sean replied 1 year ago.
Im out for a little while as soon as I get home ill dig into this and we will figure out a solution. It may require some pictures to send to me if you can.
Expert:  Sean replied 1 year ago.

would you like to work on this?

Expert:  Sean replied 1 year ago.


Customer: replied 1 year ago.
I called Honeywell, bypassed the module, dont need it, programmed stat, 5 wires ok, air came on. But fan in auto mode stayed on. Need more programming, honeywell has a case number, ill chk more today
Expert:  Sean replied 1 year ago.

Alright ill hold tight if you have any questions ill help ya.

If you wanna try and fix it we can ?

Expert:  Sean replied 1 year ago.

Just wanna touch base with you and see if Honeywell got ya squared away or if you have any questions.

IF you completely changed thermostats i would recommend Sensi if its not too late. Great easy thermostat!

Expert:  Sean replied 1 year ago.

If you can rate our conversation so we can close this out unless you need more help. Rating our conversation is the only way that we get paid for our time otherwise we make nothing for our time.

Related HVAC Questions