tranexl1200 t-stat wiring problem?

[chuga]

I have been trying to replace the old thermostat with a new digital honeywel thermostat for my trane XL1200. I hooked up the new thermostat like the old one...only 4 wires were available and I used the same color codes. It works ok, but when the t-stat turns on/off there is a loud "click click" noise. Loud enough to wake you up at night..

So, I returned the t-stat and bought a new one and get the same result. a loud click-click.

My question is, could something be wired wrong which is causing the t-stat to get damaged an "click" louder than normal when turning on/off??

When checking the wiring outside, only 4 wires are used there.

yellow - yellow wire (Y)
green - black wire(G)
white to 2 brown wires(w1/w2)
red to red(R)

from thermostat not hooked up are:
orange, blue, and black wires

from the trane the blue wire is not hooked up.

should I hook the blue(B) trane connection up to the blue wire from the thermostat??

now that I have a new thermostat should I "un jumper" w1/w2 browns and run them seperately?

my real issue is fixing the "click" noise...

thanks,

[BaldLoonie]

Good stats are relay controlled and will make a pretty good click. Mine makes 2, fan & contactor. Something you have to get used to or buy a model with electronic switching though they tend to be less reliable.

What is this? Cooling only with electric heat?

[chuga]

thanks for the reply,

it is a 2-stage gas heat, 1 stage cool unit outside.

should the blue wire from the trane be hooked up to the common on the thermostat? Right now the blue from the trane is not hooked up to anything...

thanks,

[duckman373]

You should definately rewire the furnace to run in 2 separate stages. It may be best to call in a pro to help you out though.

[Edited by duckman373 on 06-26-2005 at 04:16 PM]

[chuga]

The guy who serviced it said it automatically kicks over the 2nd stage heating, even with a single stage tstat. Is this correct? Seems like I read somewhere if you switch to a tstat capable of doing multistage you should disable the tstat in the furnace and let the digital tstat control it.

Do you think the loud clicking is normal? (the relay switch) or could it have been damaged/wired wrong and now louder?

thanks.

[BaldLoonie]

For the best comfort, you'd want a 2 stage stat rather than have the board's timer fire high in 10 minutes. That requires at least 5 wires, preferably 6 between stat & furnace.

[tpa-fl]

Everyone here's giving you the right advice... you want a multistage stat and let the stat control the furnace's staging. It'll give you a far more comfortable environment and probably will give you an efficiency boost as well.

As far as the clicking goes, it's a sign of a good thermostat, seriously. Quality thermostats use larger relays, which means they'll be more reliable over time and can handle larger loads. Cheap stats use small relays or triacs, with the latter being very failure-prone. While it is possible to damage the relays through miswiring, I'd imagine you would have caused damage to the furnace and/or condenser at the same time. (Yes, miswiring can damage more than just the thermostat) Regarding the wiring, don't go by the colors, rather go by the terminals that the wires are connected to. While some of the installers & equipment use a somewhat standard color code, not everyone does.

[chuga]

thanks..

one other question,

the "C" terminal in the trane unit outside, which has a blue wire coming from it, does not connect to the thermostat.

One person has told me that this might be causing the relay to "click" louder, because the tstat is not getting power from the blue "common" wire since it is not hooked up.

this sound reasonable??

thanks,

[BaldLoonie]

It's gonna click the same regardless of anything else.