Heating, Air Conditioning, Fridge, HVAC/Thermostat wiring hookup


I would appreciate any help you can offer to hook up my Honeywell thermostat #RTH8580 WIFI series.My old thermostat to my oil boiler(summer/winter hookup} is mechanical with only 2 wires on it (R and W).No C wire is present @ old thermostat or in wiring coming to old thermostat.I called Honeywell and what the person I talked to, said I should by a  plug-in transformer (110v to 24v out) and hook wire up to C connection.I asked her about the 2nd wire coming from transformer and she just said hook up wire to C. My question is what do do with 2nd wire from the transformer. The new  thermostat has a jumper from RC and R connection.I reviewed answer on this product on amazon and one person said they used a plug in transformer and worked for c connection(lockstate 24v adapter-transformer)

I apologize for the delayed response, been away and unplugged.

You will need to run adequate wires to turn your equipment on and off as it was with your former thermostat; and to power your new thermostat if this is required.  The only way around this is to have a battery operated thermostat that does not need power from a transformer, or to use a module for your boiler that receives a wireless signal from the thermostat.  Not wanting to sound matter-of-fact but there is no other way around running new wires; and I do realize how difficult this can be.

I put the model number into Bing, and directions and wiring images are available there.


Heating, Air Conditioning, Fridge, HVAC

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Mike Reavis


Questions related to "Wet Heat". This is heating your home, office etc. with radiators, panels, and convector apparatus. Steam and water heat. I can answer questions about boilers, piping,and associated parts of these systems. Please do not ask for specific information about how I feel about one boiler, etc. over another--These questions should be directed to a licensed contractor that you know of, or that your neighbors and colleagues look to to provide solutions.


I have 20 plus years experience, which has lead to passing my state master HVAC license.


Completed college

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I work on the manufacturer's side of the business currently

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