I recently had a new Trane XV95 (model DH2B060A9V3VA) and 2 stage Honeywell thermostat (model TH8320WF) installed in my house. I don't have an air conditioner (not needed in Anchorage AK) or humidifier or additional filtration system. The HVAC company sent two guys who had the job done in less than four hours while I was ten minutes away at work. Over the weekend while I had time to go through the installation manual and and examine my new furnace I found that they had wired it for 1 stage heating using a 1 stage thermostat (page 36 of installation manual below) presumably because the existing thermostat cable only had 4 wires. Nobady at the HVAC company explained to me that the exsiting 4 wire cable would be a limitation, and the estimator/sales guy had sold me on the 2 stage system which added $1100 after looking specifically at the existing wiring.

Now I am trying to figure out how I might be able to wire it for two stages with the 4 available wires and it seems to me that since I don't have or need AC that I could do the regular 2 stage furnace on two stage thermostat wiring (page 37 of installation manual below) except that I wouldn't have a G wire connection because I would use that wire to connect W2. I know it would eliminate the ability to control the fan independent of the furnace which I'm willing to live with for 2 stage heat.

Are there any problems with this plan that I should know about? I know that I'd have to also change function 0170 in the thermostat setup (I think 9 would be correct) and I think I'd have to change the dip switch on the IFC board for the stage delay from the default of 10 minutes to 0.5 minutes. Are there any other settings that I would need to change? Any other thoughts or comments on the situation?

Furnace installation manual: http://www.bayareaservice.com/wp-con...ion-Manual.pdf

Thanks in advace for any advice.

 

I would call them back out and insist they pull a new stat cable. At no charge to you.

 

I agree with skaggsje, you paid for a two-stage furnace AND thermostat, the least they can do is to install it properly. If they balk then tell them to take the cost out of the estimator's paycheck. If they still balk then take them to small claims court and sue for the cost of someone else making it right.

 

I agree that the HVAC company should make it right and I'm going to meet with the estimator to discuss the situation soon. As luck would have it he is out of State at the moment and when he returns I'll be gone for a few days. I'm thinking about approaching him with an offer to reduce my bill for the situation if he balks at the notion of pulling new wire which seems likely since I suspect that they'd have to tear into some walls to do it.

With that in mind I'd still like to hear thoughts about the option to move the G wire over to W2. Anyone know of problems with that idea?

 

I don't think it's a problem to try that. BTW, with a single stage stat it will still run in 1st stage and 2nd stage but it be controlled by a timer.

 

I understand that with the current configuration the 2nd stage is energized by the IFC board after ten minutes of running on the 1st stage if the call for 1st stage heat from the thermostat remains. It would then shut down and wait for the next call from the thermostat to energize W1 and the cycle would repeat. I would prefer for it to run most of the time on the 1st stage and only engage the 2nd stage if inside temps continue to fall with 1st stage engaged then keep W1 energized until both stages are satisfied. According to the heat load calcs (done by 3rd party) I should rarely need the 2nd stage but the 1st stage should run in few but long cycles. To me this seems like a big improvement over the way the old unit ran and the way the new unit is currently configured to run.

The old unit was a 26 year old Trane that was still running well but not very efficient with 80K BTU input and only 49K BTU output.