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Discussion Starter #1
I'm wanting to use a thermostat to operate a fan that will supply solar heated air, but I just cant figure out how to wire it up.

I have a standard Honeywell thermostat and a RIBU1C. I have attached a pic of what I basically want to do. I'm confused when it comes down to how to wire the thermostat. Where am I supposed to hook up those two wires on the thermostat? Do I need a separate 24v transformer to supply power to the thermostat?


Did I say thermostat enough?
 

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Very Stable Genius
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Might be easier to use a standard non-programmable thermostat which
won't require power. Wouldn't think your application would benefit from
the extra complexity and wiring a prog therm would require. Is this correct?
 

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Discussion Starter #3
Yeah. I only need something basic. I was just attempting to use a programmable one because I already had a spare.

I'm willing to get a non-prog if it helps me get to a solution.
 

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Very Stable Genius
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Suppose you want it to turn on (close contact) when the temp rises?
If so this is the opposite of most therms but still easy to find at
heating suppliers. Or you can do what I did and tear one out of a
dead window A/C. Course others will likely point out that the latter
may not give you an approved device.
 

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Discussion Starter #7
I already have the standard 18 ga thermostat wire run through the wall. Wouldn't I have run 12 ga to those types?
 

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Very Stable Genius
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No matter how you do it at some point you have to open/close
a "switch" in the wire that feeds the fan and if that fan is 120V
then it can't be 18 gauge wire. The easiest "switch" is a line
voltage tstat wired with the same wire as the fan. Otherwise it's
more complicated cuz you have to add in a relay.
Line voltage tstats are made to be mounted in device boxes....
and must be.
 

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Yes, you will need a 24 VAC transformer to power both the thermostat and the relay. A tiny little 20 VA doorbell transformer is cheap, easy to properly mount, and more than sufficient for your purpose.

Select one of the two low voltage terminals on the transformer for use as the common terminal. It does not matter which one. Connect this terminal to both the C terminal on the thermostat and the white/yellow wire on the relay. Connect the second low voltage terminal on the transformer to the R terminal on the thermostat. Connect the W terminal of the thermostat to the white/blue wire on the relay.

Which colors of the thermostat cable used don't much matter, but the industry standards make things easier:

C - Blue
R - Red
W - White

Connect the line voltage fan circuit as shown in the diagram you provided.
 
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