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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Wiring : I have a trane xl80 2 stage furnace - I am

Customer Question

JA: Hi. What is your issue regarding?
Customer: wiring
JA: I'll do all I can to help. Tell me a bit more about what's going on so we can help you best.
Customer: I have a trane xl80 2 stage furnace - I am replacing a nest with a honeywell rth2300b
JA: Is there anything else the HVAC Technician should be aware of?
Customer: not sure where w2 goes
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and then connect you two.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello tell me what model NEST you had wired, and what color wires went to each terminal on the NEST, and how long you ran the system with the NEST connected, and how well that worked.

The wiring can get convoluted changing to and from a NEST depending your entire system, not just the furnace, but the cooling... does the unit outside run in the summer only .. or does it run in the winter as well.

I need all of this information in detail in order to help you.. post your responses here, we can go from there.

Customer: replied 1 year ago.
1. Nest was running fine for 6/7 years.
2. C, G, RH, W1, W2 are the wires available.No cooling.
Customer: replied 1 year ago.
C G RH W1 W2
green blue yellow white red
Expert:  Phil replied 1 year ago.

W2 is second stage heat, used on two stage furnaces and on heat pump systems for back up heat.

Tell me which terminals are on the Honeywell thermostat, so far it looks like a single stage heat only thermostat, you need a two stage heat thermostat.

I still need to know if you have a heat pump outside that runs in the winter as well as the summer, or just the summer, cooling only....that is crucially needed information in order to get the correct thermostat... there are hundreds on the market.

Customer: replied 1 year ago.
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** a single stage heating thermostat... it will also accommodate a heat pump... if the unit outside does not run for heating in the winter, then you have the wrong thermostat on two counts.

You have not told me yet if the outside unit runs in the winter or not, so I cannot specify the correct thermostat for you.

Let me know, we can go from there.

Customer: replied 1 year ago.
I never said there was an outside unit. I dont know what you are referring to.
Expert:  Phil replied 1 year ago.

Hello again, I apologize deeply. You said 'no cooling' I *assumed that you had cooling along with the furnace, and that it was simply not working.....and in that case there would be a unit that sits outside that runs in the summer.

That said, the issue of a W2 terminal remains... that is the *second stage* heat function. Your old NEST thermostat had second stage capability, the new thermostat you bought does *not have second stage capability.

In other words it is the wrong thermostat for your system.

Any 'conventional two stage heat ,24 volt thermostat that includes the following terminals, R, G, W1, W2, and C will work' if you get one that one *does not say 'heat pump' anywhere on the box, it will also be easier to wire and program. If it says 'heat pump' on the box, along with the words 'conventional system' and includes and O/B terminal or terminals then it will be more difficult to wire

Such a thermostat will generally also have a 'Y' terminal, that is for cooling, if you do not have cooling then simply do not connect it.

Again I apologize, on this end I am 100% totally blind to what you have, so I ask questions to narrow that down. There are literally thousands of different configurations the market... first step is always to determine which of that range of options that you have.

If you want to buy the thermostat locally, take this note to one of the more experienced clerks in a large hardware store that sells thermostats, then have them select a 'conventional 24volt thermostat with two stage heat' (that is not also for heat pump).

If you are going to buy it on line, just say so, and I will located one for you.