Keeper
I put the 24V adaptor in the furnace room and ran a homedepot 4 wire t’stat wire up to the tstat.
This setup is in my cabin so don’t have any pics.
Apologies for reviving such an old thread, but I’m considering doing precisely what has been discussed towards the bottom here. My thermostat was wired with an old two wire connection to the furnace, and while the furnace supports the 5 wire style, it is extremely difficult to deliver a new wire to the thermostat location. The old wire is stapled to the joists, and pinned between various pieces of frame and sheetrock in my partially finished basement. Pulling the cable through has proven impossible and running a new one would be extremely tricky. I do have a good 120v power source directly underneath the thermostat’s location however, so wiring up an additional two wire lead from a basement mounted wall wort to the thermostat would definitely be doable.
It seems that with two wires from the (heat only) furnace, and two wires from the 24v power brick, I’d be in business.
In reference to @soconnorny’s question, there should be no reason that this wouldn’t work with the TRANE since both of these models are designed to be powered off relatively standard furnace transformers. If I get around to trying this, I’ll let you know.
Anyone else have any experience with this wiring setup they care to share?
Thanks!
To answer my (any others) question on this. Yes, you can quite easily connect up a 24v AC (not DC) power supply to any of these 24v thermostats. Note that many of these power supplies actually provide 26.5V instead of 24, which is exactly the same as what my furnace provides, and is just fine for use with these thermostats. As for the amperage ratings of power supplies, this rating is really only a “max” rating. Meaning you can connect any load that uses UP TO the maximum amperage rating. So a 500mA vs a 1000mA (1A) power supply doesn’t matter.
I successfully hooked up my TRANE ZWave thermostat (model TZEMT043AB32MAA) using a Rainbird UT1 power supply from home depot, that I picked up locally for under $15. (also at Amazon.com for under $10)
[url=http://www.homedepot.com/h_d1/N-5yc1vZ1xh8/R-100201044/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053]http://www.homedepot.com/h_d1/N-5yc1vZ1xh8/R-100201044/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053[/url]
I had it all tested out down in the basement with 24v coming from the UT1 power supply and a two wire thermostat cable connected to the furnace, it worked perfectly. Unfortunately for me I managed to break my existing 2-wire thermostat cable inside of a finished wall as I was attempting to run the two new wires for 24v to the old thermostat location. Long story short it was in a very difficult place to fish new wires, so ended up having to relocate the thermostat and ran a brand new 5 element wire from the furnace, rendering this whole conversation moot (for me). I did learn a lot about how thermostats and furnaces are wired during this process though.
Thanks for providing this info. I am new to this and don’t want to fry a $150 trane z-wave so please tolerate my ignorance:
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Where do you hook the wires from the wall transformer to? just Rh and the common? I figure the two wires coming from the heater (red and white) go to Rh and W.
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Does polarity coming from the external power source matter? If so, how do I determine it.
Thanks,
Polarity doesn’t matter since it’s a low voltage AC load.
You just hook up the power brick to the top terminals labeled 24C and 24RC if I recall (you can also use 24C and 24RH since RC and RH are bridged with a jumper by default. ).
I’m sure you’ve read through this:
[url=http://www.trane.com/residential/downloads/RemoteThermostat/Installation%20Instructions.pdf]http://www.trane.com/residential/downloads/RemoteThermostat/Installation%20Instructions.pdf[/url]. You can see the wiring diagram on Page 6… basically you are just replacing the top two wires with your power adapter.
I hope this helps.
Here is a site that also describes Thermostat wiring:
http://wiki.xtronics.com/index.php/Thermostat_signals_and_wiring
Uggh, just got around to attempting to install my trane tstat. I had changed out the original one with a timer/programmable one a few years ago, so I thought this would be simple.
RED, YELLOW, GREEN, WHITE are currently in use. Both stats (previous and current non-zwave) have batteries and the BLUE (24COM) wire was not connected at the gas/AC unit, though BLUE and BROWN are in the stat control wire bundle (but neither is connected at either end).
I pulled the panel off the gas/AC unit, found the blue, and it measures about 19V AC, so i connected it to the blue control bundle. The stat will not power up using the BLUE even though I read 19V between RED and BLUE. My understanding is the BLUE is constant 24V to power the stat.
I found a wallwart 24V AC supply, attached it to RED & BLUE inputs on the Trane, and it powers up just fine and connects to Vera. Both the wallwart and the gas/AC feed read about the same voltage (19V AC), so I’m confused as to why it will not power up off the supposed BLUE from the gas/AC unit.
There’s no easy way to power the wallwart at the current stat location. I’d really like to pick up the appropriate 24V from the gas unit itself.
RED to BLUE reads 19V AC, but does not power up the stat. Not enough current? Any thoughts?
Worst case couldn’t you just put the walwart down with the furnace and use it to power red & blue from there?
-GT
Is there any indication on the unit, or another way of verifying that the blue wire you found is indeed a 24COM supply wire? (If you have the Trane connected and measure, do you still get 19VAC?)
I’m gonna dig into this again today, and I’ll check the blue voltage with a load/stat on it.
The central unit is a combo gas/AC and is outside, so I’d rather not put another power supply there.
OK. Do you have a model# / pointer to a manual for the combo unit?
The central unit is a combo gas/AC and is outside, so I'd rather not put another power supply there.I see.
I’m pretty sure this is the unit:
http://www.armstrongair.com/better/13-seer-gaselectric-compact.html
unfortunately, the document links are bad.
Got it. I took the tstat to the central unit and attached to the blue and red (which read 28V) and it worked. So I knew the control wire was the problem. I got in the crawl space and the control wire had been spliced, but the blue (and brown…both unused) were not spliced. Hooked 'em up and it is now working.
I guess the 19V I was reading was leakage, very micro amps from the red hot.
Now to figure out how to program the thing.
Excellent; glad you got it! The 19VAC (unloaded) did seem low.
Since this thread has been resurected, I thought I would chime in…
I needed a few more Rainbird UT-1 24VAC power bricks to complete my Trane thermostat installs, there was a lot on eBay with multiples, so I bought it. Used what I needed, and have 5 or so left, if anyone needs one. Cost was low (since if only had 1 shipping charge for the lot), so I think I can get these shipped out via USPS flat rate boxes for $11 each if anyone needs one. PM me, thanks Mitch