SIngle Stage Thermostat with a 2 Stage Furnace

[ryzvy]

I am in the process of changing the HVAC system in my house (2 level, 2300 square foot plus attic) with a Trane XL14i air conditioner (4 tons, 13.5 seer, R210a) and an XL19i dual stage furnace (92%, 110K BTU). My old thermostat used a 5 wire cable. The thermostat that came with the new system uses 6 wires for the 2 stage heating. The instructions says I can use it as a single stage thermostat with a 5 wire cable by jumpering the connections W1 and W2; but if I do this the second stage heating will kick in 10 minutes after the first stage starts. My concern is am I losing any efficiency by using the thermostat this way? Will the second stage heating kick in automatically after 10 minutes even if it is not required? Should I try an run an additional wire?

The furnace is heating the house fine so far, but it has not gotten very cold yet. I did however notice that the heating cycles on and off frequently. After the house reaches the set temperature (68 degrees), the furnace shuts off but the blower keeps going for a few minutes then shuts off as well. Then after about 10 minutes they both turn back on again. Sometimes they turn off again in less than 5 minutes? Is this frequency of cycling common or do I need to have a chat with the guy who installed the furnace? As I said, so far I am happy with the heating as my previous furnace was a nightmare and used to run non stop without heating the house much. I regularly got gas bills of over $600 a month the past couple of winters. I will be just happy if I can cut that down somewhat.

[seadragon]

Absolutely run the extra wire if you can and use the 2 stage feature of the thermostat. Your furnace will run much better with the thermostat controling staging. I was in a similar situation when I first got my system and the furnace ran on high stage quite a bit. After setting the thermostat to control staging, it will run on low for up to an hour or so then shut off. It rarely goes on high stage, except when coming out of setback in them morning.

You will not get the full advantage of a 2 stage furnace unless you let the thermostat do the driving so to speak.

[mayguy]

What brand t-stat you got for two stage?

most of the time you can use 5 wires, and just use the battery for power. Hook it up to two stage, you'll be happy with the comfort, and long cycle time. Make sure the t-stat is set at 3 CPH

[BaldLoonie]

White-Rodgers 1F85-277 will do 2 stage heat with 5 wires. Runs off batteries. The Vision Pro IAQ will do everything imaginable on 3 wires. '

The XL19i is an air conditioner or heat pump, not furnace though.

[chaard]

Your furnace wil run with a single stage t-stat. The furnace will switch to second stage itself when the t-stat hasn't been satisfied after ten min.

As for the blower running, you need a pro to set the blower off delay dip switches, so that you not cooling down the house in between off cycles. The blower will run for a min. of 90 sec. after the last call for heat.

[ryzvy]

Originally posted by mayguy
What brand t-stat you got for two stage?

most of the time you can use 5 wires, and just use the battery for power. Hook it up to two stage, you'll be happy with the comfort, and long cycle time. Make sure the t-stat is set at 3 CPH

Thanks to everyone for all the helpful suggestions/opinions. The thermostat is a Trane that came with the system. Its one of those touch screen models with 7 day programming. XL800 series I believe; don't know the exact model number. So I think I will forego the 24 V power and use that wire for the second stage heating. Does the t-stat retain its settings when I change the battery or do I have to re-program everything from scratch?

Is the 5-10 minutes cycle time for a furnace too low?

The XL19i is an air conditioner or heat pump, not furnace though.

My bad, I meant to say XL90.

[ryzvy]

Originally posted by mayguy
Make sure the t-stat is set at 3 CPH

How do I set this?

[BaldLoonie]

The Honeywell/Trane touchscreen stats run on battery too and can use 5 wires. Makes such a comfort difference to use a 2 stage stat. Stat should retain all settings when changing batteries. Check the installer setup to make sure the dealer set to 2 stage, Option 170 setting 9. Also where you reduce cycles to 3. Option 240 I think.

[ryzvy]

Originally posted by BaldLoonie
The Honeywell/Trane touchscreen stats run on battery too and can use 5 wires. Makes such a comfort difference to use a 2 stage stat. Stat should retain all settings when changing batteries. Check the installer setup to make sure the dealer set to 2 stage, Option 170 setting 9. Also where you reduce cycles to 3. Option 240 I think.

Thanks! How do I view/change "installer setup"? Is there a special menu?

[mayguy]

It all should be in the installer manual that came with the t-stat.

When it's wired up to W2 at the t-stat, make sure the jumper is rempved at the furnace so it not using the timer.

[ryzvy]

Originally posted by mayguy
It all should be in the installer manual that came with the t-stat.

When it's wired up to W2 at the t-stat, make sure the jumper is rempved at the furnace so it not using the timer.

Hmm I did not receive the installer manual, or at least the guy did not give it to me. All I received was a single sheet of paper with the wiring diagrams and the glossy brochure with general features.

[morris nj]

I just had a Vision pro 8320 installed on a Trane XV80. my CPH is set for 5? Would that be correct for an 80% Furance. I think 3 is for 90% and above.

[ryzvy]

It all should be in the installer manual that came with the t-stat.

When it's wired up to W2 at the t-stat, make sure the jumper is rempved at the furnace so it not using the timer.

Is there some place I can download this installer manual from?