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Thermostat for variable speed blower

bobkbobk Member Posts: 16
Greetings. In my new house I have an Amana (AMVC950905DXAB) gas furnace and Goodman A/C. I installed an ecobee thermostat last year, and since I only have 4 wires, I used the G wire for C, since the ecobee needed a C wire. The heating/cooling in the house seems uneven, so I thought I'd try leaving the fan on all the time, but of course, that means I need the G wire. I bought a cheap Honeywell thermostat and hooked it up, but "fan on" doesn't work. I think it's because I have a variable speed blower, two-stage furnace, and it needs some other kind of voltage. Is this right? If so, can anyone recommend a thermostat that will work? and doesn't need a C wire?
And what about the uneven temp in the house? Is leaving the fan on the right thing to do? Honeywell sells sensors for other rooms that communicate with the t-stat -- does anyone have experience with those?


  • mattmia2mattmia2 Member Posts: 2,002
    Did you try adjusting the balancing dampers in the ductwork?
  • HVACNUTHVACNUT Member Posts: 3,582
    Well, run a new 8 conductor thermostat wire. Why have a 2 stage furnace if you're not going to take advantage of it? Does the ecobee have W1, W2? Is it 2 stage A/C?
    Or a Honeywell Pro9000WF with RedLink gateway and EIM (equipment interface module). You only need 2 wires at the thermostat. R and C. 
  • bobkbobk Member Posts: 16
    Thanks for your suggestions. I've done some reading and realized I'm in over my head. doesn't take much. The manual for the furnace recommends a ComfortNet CTK01A communicating thermostat. If you don't have one of those, You can select single stage thermostat with a dip switch on the motherboard, and then stage transition is on a delay -- you can select auto, or set the delays with dip switches. The blower speed should be 30% of max if continuous fan is set on the thermostat. So it should work the way I have it, with the single stage thermostat, but the continuous fan setting doesn't work. I'm beginning to think my new thermostat is defective.
    Any more suggestions?
  • HVACNUTHVACNUT Member Posts: 3,582
    You removed the Ecobee and replaced it with a cheap Honeywell? So now there's no Common but no need. Battery powered. If you jump R and G at the thermostat sub base, the fan should come on at 30%. If not, try the same thing at the board. 
    Put the 2nd stage dip switch on auto.
  • bobkbobk Member Posts: 16
    Ok, thanks. I can try that. I was kinda hoping I could select fan on with the thermostat switch. that's why I replaced the ecobee -- to get back the G wire I had used for C.
  • unclejohnunclejohn Member Posts: 1,661
    Use the tstat that the manufacture recommends. Some variable speed fans require a "G" and a "Y" input to work properly in the cooling mode. You will also get cool to dehumidify with the right tstat.
  • bobkbobk Member Posts: 16
    Thanks. That sounds like the right thing to do. Unfortunately, the dang thing is pricey. The CTK04, the most recent version, is $500!
  • ratioratio Member Posts: 2,614
    True, but if it's the communicating stat, it only needs 4 wires to operate; & the communicating stat the only way to get the highest performance out of the system…

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