SOF Chiller, Bought 24 VAC Tstat!

[moparx12]

I didn't realize i bought the wrong thermostat at the time, and i would rather just use the right thermostat but now i have already invested in a 12 volt fan and a 12 volt relay. both have been modified by cutting wire and soldering so there is no returning them.

I bought the thermostat for $2 at Wal-Mart because the package had been opened.

Is there an easy/cheap way to make this work? it is a heat only honeywell tstat, model CT87K. I looked at the guide and bought the radio shack relay to turn it into a cool only tstat.

Someone mentioned using a zener diode in conjunction with a resistor to regulate the ~24vac that will be coming out of the thermostat and into the relay. Even if this method works for the fan, will it work for the relay? the relay is 275-241.

I am willing to purchase a doorbell transformer to get down to 24 vac i just don't know how to get it to work with the relay and fan that i have.

If i have to buy much more than a transformer to make this work, ill have to just buy a mechanical thermostat.

 

[moparx12]

I saw this tstat on line and i think im gonna pick it up tonight. Seems like the most practical solution. Does anybody else have this one?

http://www.lowes.com/pd_155771-79-4...antity_sold|1&storeId=10151&searchQueryType=1

 

[jtrainer]

I think thats the same one I used for years. I followed the SoFC guide for the parts and wiring guide. Worked like a champ...

I'll admit, I paid full price as my tstat was not working... turned out a wire nut popped off and the unit wouldn't power up. So ther it sat for 6 yrs until I needed it for the SoFC build...

http://home.roadrunner.com/~brewbeer/chiller/chiller.PDF
From Page 10:
Another approach which will be less expensive (under $10) but requires some soldering is to use a heat-only thermostat to operate a relay.
This effectively converts the thermostat to a "cool-only". Radio Shack's 275-241 relay is very tiny, and will mount inside most cheapie
thermostat housings with a little hot glue or two-sided foam tape. Wire the relay in series with the thermostat so that its coil is energized when
the thermostat turns on. Use the "COM" (common) and the "NC" (normally-closed) relay terminals to switch the fan. Now, when the
thermostat turns "on", meaning it's "too cold" (this is a heating thermostat, right?), the NC relay contacts will turn "off". The fan stops and the
Chiller eventually warms up. The thermostat, sensing that it's now "warm enough", turns the relay "off", which closes the NC relay contacts
and turns on the fan.

 

[moparx12]

I went ahead and bought that tstat and am using the 12v relay. Seems to work good so far!