Wiring Help: Honeywell Wifi Thermostat


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Old 09-07-14, 11:14 AM
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Wiring Help: Honeywell Wifi Thermostat

So I just picked up a Honeywell Wifi RTH9590 and tried to install it but I am completly stuck and thinking I might have to return it.

So my current setup is just heating. I have oil / baseboard. The wires coming up from the boiler is just 2 wires, RH and W.

Here is a pic from the heaters control panel

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The instructions for this unit clearly state I need a C wire. Well I am only trying to use this for heat, as I have a in wall AC unit.

Anyway to make this work? Please help
 
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Old 09-07-14, 01:25 PM
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Here is a link to a recent thread that discusses how you may be able to install an external 24V transformer to supply power for the C terminal on your new thermostat:

http://www.doityourself.com/forum/ai...ansformer.html

Here is a link to a manual: http://pdf.lowes.com/useandcareguide...890762_use.pdf

Looking at the instructions for alternate wiring on pages 16-17 it seems like it should be relatively easy to do with an external transformer.

What type of thermostat are you using currently?
 

Last edited by firedawgsatx; 09-07-14 at 01:48 PM.
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Old 09-07-14, 01:46 PM
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Welcome to the forums.

There may be a C connection at that Honeywell control but we'd need a larger pic of the whole thing and the part number. It would be LA-XXXX

You would still need a third wire to the thermostat from that area.

If you choose to use a separate power supply to run the thermostat - you could use any 24vac 20watt unit.

24vac transformer power supply | eBay
 
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Old 09-08-14, 05:19 PM
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Can you fish a wire from the boiler to the Tstat location ,maybe using the existing cable as a pull string,if so post a pic of your boiler controls,the best way is to use the existing transformer on the boiler.
Geo
 
 

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