Having problem with 2 stage furnace

[nortonma]

i have a Trane 80% gas 2 stage furnace which i believe the second stage is not coming on. There is a single stage thermostat and w1 and w2 are jumped out on the board. How do i tell if the second stage is coming on.

[chapmanf]

Do you mean W1 and W2 are jumpered together? Are you sure it isn't the first stage that's not coming on?

[markwolf]

What a hack thing to do......install a two stage furnace & only use high fire!Have a two stage stat installed!

[Jultzya]

Guys, guys, guys...

While I wouldn't install a single stage stat on two-stage equipment, it will fire both stages of heat.

It will first start up on "low fire" and continue to run till the board timer "times out" and kicks in the second "high fire" stage. Then shuts down after the stat is satisfied.

But the comfort and efficiency is lost by not using a quality two-stage stat.

[chapmanf]

While I wouldn't install a single stage stat on two-stage equipment, it will fire both stages of heat.

It will first start up on "low fire" and continue to run till the board timer "times out" and kicks in the second "high fire"

Yes, that's the plan, when the board is correctly wired and configured for use with a single stage stat. The details would have to be in the manual for that specific board, but I was concerned that jumpering W1 to W2 could be overriding the on board timer and selecting high fire unconditionally. I was not suggesting that has to be the explanation, but if I saw it I would sure go to the manual for that furnace and make very sure that was the correct way to wire a single stage stat.

[curry]

Man. I sure am glad I got a seminar scheduled for these two stage and VS sytems.

[BaldLoonie]

On a Trane, W1 and W2 jumped triggers the 10 minute timer.

[chapmanf]

OK, I withdraw my question. (at least it did its job of getting somebody who really knew the answer to post. )

[chapmanf]

And then to the OP's question ... I take it you're watching the unit carefully for more than 10 minutes and you're not noticing the firing rate change? It can be easy to miss if you're not watching and listening right when it changes. The sound of the inducer might be the best giveaway. One some units (don't know Trane) the inducer always starts on high draft for the prepurge, drops to low draft for ignition ... then will return to high draft after timer runs out. If you can give more info on exactly what you're seeing that makes you doubt it's working right, someone might get an idea.

[gje1]

BoldLoonie is right, but i would check the dip switches to make sure they are in the correct positions for 2 stage firing and not in high fire mode. See the owners manual. You should easily be able to hear the difference between high fire and low.

[Jultzya]

Originally posted by chapmanf
OK, I withdraw my question.

If you don't jumper them, how is the unit going to know whether it's a single stage or two stage stat?

[docholiday]

I dont know the trane, but the logic would be if you use a two stage stat you connect it to w1 for first, and w2 for second, if you jump w1 and w2, you in effect fire it on high. If you use a single stage, you wire it into W2. The furnace board should recognize this as a single stage stat because it recieved the call on W2 without a call on W1. Again, Trane may be different. Now if the board has a dip switch that needs to be configured then I would start there, fix that and wire per the wiring diagram.

[Jultzya]

W1 is first stage
W2 is second stage

single stage stat will be wired to either W with them being jumpered to take advantage of the onboard timer.