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pconrad 12-07-2008 09:46 PM

Twinned Trane XE80 issues
I have two trane XE80s that are twinned. The secondary one stopped working. Looking at the flashing lights shows that there is no call for heat on the second one. I swapped the control boards so I know that the basic functions work. How can I test to see if the correct voltages are being supplied/applied for the twinning circuits?

beenthere 12-08-2008 03:33 AM

Need a multimeter.

How are they twinned. Which wiring method was used.

pconrad 12-08-2008 09:25 AM

They are twinned with the single wire method. (It actually uses two.)
1 wire connects each Twin lead, and the other connects the G lead.

beenthere 12-08-2008 11:12 AM

How is the heat controled, if there is no wire hooked to the R???

Without a wire of some kind hooked to teh red, it won't have a heat call.

The twin terminal is to sycronize the blower speeds.

pconrad 12-08-2008 11:55 AM

Whoops! They are connected with the Twin and the W lead like the doc in the link shows.
I don't see an isolation transformer in my system.

beenthere 12-08-2008 12:04 PM

If they are on the same breaker in the box, its not needed.
If they aren't its needed.

Sometimes, a system needs the isolation relay. But the installer doesn't use one. And they work for years. And then just stop working.

You need amultimeter/voltmeter, to see what, if any voltage is at the W terminal, of the working and non working unit.

May be that the thermostat can't handle the load, anymore.

pconrad 12-09-2008 08:07 AM

It was much simpler than that. While checking voltages, I found a broken wire. Once that was repaired, the system came back to life.

Thank you for your time.

beenthere 12-09-2008 11:26 AM

Your welcome.

Meters, they save a lot of duessing.

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