110volt Thermostat to Low Voltage Thermostat


Old 10-01-03, 11:59 AM
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Post 110volt Thermostat to Low Voltage Thermostat

Is it possible to convert a 110 volt AC thermostat to a low voltage programable thermostat? I notice that stores do not have 110 volt AC programable heating thermostats. Is there a reason? I have allways had a programable and its driving me nuts. Thanks.

Home Built in 1970
Original Tstat (slide type HoneyWell?) and oil burner.
One zone
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Old 10-01-03, 12:51 PM
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Join Date: Aug 2002
Location: Mountain Williams Missouri
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Dont know for sure what you want here. You have a oil burner you say, that should have a 24 volt tstat on it. Or you said zone could the tstat turn on the pump110v and the oil burner works off the limit on the boiler? If so you could get a programmable 24 tstat for the zone and run it off a relay set up for the zone ED
Old 10-01-03, 06:17 PM
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here is what I have

The thermostate that I have reads 110 vac and no 24 volts. In the upper right corner of the picture thats where the thermostat wire goes to and that reads 110 vac as well. I labeled the picture from what was printed on the circuit board. I have bought several of the programable tstats and they say that I cannot use 110vac. Thank you very much for your help.

Old 10-02-03, 05:46 PM
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I found something on another site. It was a transformer that reduced the voltage from 110 vac to 24 volts. Do I need something like that? I went to Home Depot and they cant be bothered. Lowes did not know....
Old 10-02-03, 06:06 PM
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Alittle hard to see both controls. But it looks like it can
be done. May need to hire a contractor to rewire controls properly.
Old 10-02-03, 07:00 PM
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Location: Easton, PA
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The thermostat terminals on your control (looks like a Honeywell 8048) are set to switch using 24 volts. There is a jumper in place there now which enables the use of the line voltage thermostat. It looks like things may not be completely original in that control because I see a wire nut nestled in there. But back to the thermostat. If you removed the wires that lead to the existing thermostat and connected them together and then removed the jumper on the thermostat terminals and connected the wires that lead to your thermostat, you will have accomplished what you were after. Low voltage control of the relay. However, I have to wonder why it is set up this way. The terminals you have marked 120 vac should be powered all the time. Be sure that you know where the power comes from for this circuit. The thermostat wire should be continuous from the control to the wall where the stat is mounted. No junction boxes with surprises inside.

You also do NOT have a wire connected to the C1 terminal which is the one that powers the circulator. That means you have other wiring modifications to cause you grief. It might be simpler to walk through this project terminal by terminal and get all the weirdness out at once. You will need to face the possibility that the control malfunctioned and someone rewired instead of replaced it.
Old 10-03-03, 06:56 PM
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Thumbs up Thanks

Thanks alot for your help. I know what needs to be done. I have been procrastinating for 3 years on this project . Thanks again

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