Convert Trane XL90 to Stage 2 Thermostat Controlled


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Old 01-02-19, 09:56 AM
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Convert Trane XL90 to Stage 2 Thermostat Controlled

I just completed the wiring for my Honeywell Lyric 2 stage stat W2 connection to the furnace W2 connection and the set-up of the stat to two stage. The question I have is there any other setting or dip switch setting needed on the furnace or the control board?
 
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Old 01-02-19, 05:16 PM
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Welcome to the forums.

If it was setup for single stage previously then yes.... you will need to make changes.
Post the full model number of the furnace. It can be found inside on the side wall near the burner.
You could post the part number off the control board too.
 
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Old 01-03-19, 07:14 AM
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The model number is TUX100R943W3
thank you and I look forward to your responses.
 
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Old 01-03-19, 06:46 PM
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Apparently all that's needed is to jump W1 to W2 for single stage heating and to remove the jumper for two stage thermostat operation. If you had W1 and W2 jumpered.... opening the jumper is all that's needed. A little service info for your unit. Download it so you have it.

Manual for your furnace (pdf)
 
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Old 01-04-19, 05:52 AM
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Hi Pete, thank you very much for the information and manual. This is what I have done already - remove jumper between W1 & W2.. I can tell that stage 2 is getting initiated at beginning of heat cycle when stat is heating more than a couple degrees. However, it then falls back to stage 1 during the first 30 seconds or so. Would this sound like a mechanical issue or control board?
Thanks again.
Ron
 
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Old 01-04-19, 05:10 PM
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Try this..... remove the W2 wire at the furnace and see how it reacts.
If acts normally it would be the stat calling for stage 2 heat.
 
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Old 01-05-19, 06:10 AM
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Yes, I did this and the furnace did not attempt to go to stage 2 during start of cycle. Reconnected and set stat to heat 5 degrees and it did attempt to go to stage 2. Do you think this is a stat setting on Lyric, control board problem or mechanical issue? My thinking is the stat is working and control board is working but another issue within high heat.
Thanks for your thoughts.
 
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Old 01-05-19, 09:21 AM
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You're saying that stage 2 does not come on with W2 disconnected. That means the stat is powering W2. That would eliminate a furnace problem

I don't know if it's a setting or just how the heating algorithm is set up. The stat will call for stage 2 heating if the the set temp and room temp are more that a few degrees apart. I'm not sure what that exact figure is.
 
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Old 01-07-19, 03:48 AM
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I agree with you and believe the stat is controlling W2 stage 2. The problem I am trying to determine now is when W2 is initiated (either by stat or board) it begins to fire but does not and reverts to stage 1. Is this control board or a mechanical issue. During my annual inspection the HVAC guy is recommending s new board and says no problem mechanically. But if stat now is signaling W2 and not the board - is the board really bad?
 
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Old 01-07-19, 10:16 AM
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Did you set your stat up for 2-stage?
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Could be caused by a pressure switch issue - there's a second pressure switch for second stage that must close. The inducer should speed up, close the switch to allow it to run on high fire.

It may be reverting back to first stage rather than shutting off and giving an error code.
 
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Old 01-07-19, 10:32 AM
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yes. I did change the stat from single stage to 2-stage. Is the pressure switch controlled outside the control board? I don't believe the HVAC technician tried 2-stage activation by the stat and just assumed it was a control board issue @ $970. I have no problem paying for a fix - this just doesn't smell right.
 
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Old 01-08-19, 08:13 AM
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Can you give a little bit more about the pressure switch that may be faulty?
 
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Old 01-08-19, 11:46 AM
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When there's a call for second stage, it should attempt to go into second stage.

If there's a problem, it may flash an error code and then drop back to low. You have to monitor it to see what it does.

The pressure switches make sure there's a proper draft through the heat exchanger. High fire uses higher venter motor speed and the high fire switch is supposed to close.

The diagnostics are done with a multi-meter checking voltage drop across the switch if it gives a high fire pressure switch error. If the switch is not closing, there could be a reason and replacing it could be a waste of money.
 
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Old 01-08-19, 01:36 PM
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Thank you! This is good information. Let me give it a try. thanks again.
 
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Old 01-11-19, 03:12 PM
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In looking at the error code, it looks like it is 7 flashes when it is in stage 1. Does this lend any idea if it is related to the stage 2 issue?
 
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Old 01-11-19, 11:09 PM
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the error code info should be on the schematic on the blower access panel, side facing into the furnace.

see what 7 flashes mean.
 
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Old 01-12-19, 10:31 AM
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It says GAS VALVE CIRCUIT ERROR.
Thanks
 
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Old 01-14-19, 10:06 AM
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The Furnace appears to be running fine and having no problem with gas flow from what I can tell. Any ideas why it shows this error during full stage 1 heating cycle?
 
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Old 01-14-19, 11:58 AM
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Is it giving the error only with a thermostat or board timer call for high fire?

The 2-stage gas valves have 3 wires -> common, low fire and high fire and it may be wise to ohm it out from the molex connector in the board to rule out gas valve and connections to it.
 
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Old 01-14-19, 05:41 PM
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I get the error code even when it calls for stage 1 and only heating 1 degree temp change.
 
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Old 01-14-19, 05:46 PM
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That's odd.

And it's not going into second stage when the stat calls for it with a wire between W2 terminals at furnace and stat?
 
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Old 01-14-19, 06:37 PM
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Not sure if this help but figured I'd throw it out there.

I have an XL90 but I'm controlling it with a Nest G3. It was pretty simple to get up and running. I removed the jumper and wired in the W2. I went into settings and told the Nest about the W2 and everything worked great. I did have to change the timer jumpers on a Honeywell zone controller but that shouldn't apply to you.

The Nest will display when a Stage 2 call is made, It needs about a 4+ degree differential before it will do so. Can you find out if the Lyric is displaying a Stage 2 call or if it should do so? Do you know what the logic is for a Stage 2 call?
 
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Old 01-15-19, 04:10 PM
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I experienced the same with Lyric, easy to setup to stage 2 and W2 connection. I am still not sure of the algorithm to kick in stage 2. My understanding is if the stat controls stage 2/W2 it kicks on at start of call for heat where if control board controls high heat it runs for a while ie 15 mins and then kicks into stage 2. I was able to clearly hear a difference when setting stat to temp difference by +5* and cold outside 10* and then it dropped to stage 1. At that time I did not know about error code and since then I have experienced several cycles of error code 7 for sure at stage 1 and may have had stage 2 kick to stage 1 but not 100% sure. My question at this point is I regularly trigger stage 1 heat (1-2 degree increase) and get error code 7 during entire heating cycle with no problem. What does gas valve circuit error mean while it is operating as normal? Could this also be same cause of stage 2 failure?
thanks all for your input - I appreciate it.
 
 

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