Replacing Chronotherm III with Vision Pro
This should be simple but I'm not 100% sure about the wiring...My current Honeywell Chronotherm III model # T8601C1021 has failed (keeps deleting the return program). I want to replace it with the Honeywell VisionPro Model # TH8110U. The installation instructions for the VisionPro show a jumper between the R and Rc terminals where on the Chronotherm III there is no jumper, in fact there is no terminal screw at all at the Rc position. So the question I have is do I leave the jumper in place on the VisionPro or remove it and only have a wire going to the R terminal? Current wiring at Thermostat: O - No wire W - White wire G - Green Wire C - Red Wire R - Red Wire Rc - No terminal screw or wire B - No wire Y - Yellow wire Current wiring at Heater Control (ArcoAir/Inner City Products Furnace Control Model 50A50-112): Y - Yellow wire to thermostat and outside AC compressor (ArcoAir Model AD042G) W - White wire to thermostat R - Red wire to thermostat and wet switch (red wire) G - Green wire to thermostat C - Red wire to thermostat 2 wires of wet switch (Green Black) Additional orange wire from the wet switch goes to a red wire that goes to the outside AC compressor. I know this is a lot of wiring info for what is probably a very simple question but I figured too much info is better than not enough. Thanks. Originally Posted by jedicarl The installation instructions for the VisionPro show a jumper between the R and Rc terminals where on the Chronotherm III there is no jumper, in fact there is no terminal screw at all at the Rc position. Some older stats had to work with one system only, now most newer one can work with two.. So being you have one system, the jumper stays. Other than that, it will be a easy swap out. Is your furnace a 90% or what? C - Red Wire R - Red Wire Be sure you make note what red wire went to C, or you may burn up the transformer. R - Red wire to thermostat and wet switch (red wire) C - Red wire to thermostat 2 wires of wet switch (Green Black) Not sure what you mean by the wet switch? Is this a cut off switch for a pump? Originally Posted by Jay11J Is your furnace a 90% or what? I don't know, it was installed in 1993 and I can't even find the nameplate label. It's an ArcoAir GNI Series, Inducted Draft, High Efficiency Upflow/Horizontal Gas Fired Furnace. I have the installation manual and operating manual but neither lists the specs or the efficiency. I did find a label that said the input is 80,000 BTU/hr and the output is 64,400 BTU/hr...64,400/80,000 is 80.5%...not very efficient. Originally Posted by Jay11J Be sure you make note what red wire went to C, or you may burn up the transformer. Thanks, I already decided I would need to be very careful to label the wires since I have 2 red! Originally Posted by Jay11J Not sure what you mean by the wet switch? Is this a cut off switch for a pump? No, it's a water leak monitoring device. It sits in the overflow pan underneath the AC coils...it shuts off the system if the primary drain system malfunctions and water starts to collect in the overflow pan/drain system. Thank you very much for your reply, I assumed that I would leave the jumper on for my system set up, but you know what they say about assuming... Originally Posted by jedicarl I did find a label that said the input is 80,000 BTU/hr and the output is 64,400 BTU/hr...64,400/80,000 is 80.5%...not very efficient. As mild your winters are, 80% is fine. In the installer set up menu, #240, I know the book says put it to 5, but I would suggest you to set it to 3. (Longer run time, less cycle on and off) Thanks, I already decided I would need to be very careful to label the wires since I have 2 red! Take a marker, or tape and label it C No, it's a water leak monitoring device. It sits in the overflow pan underneath the AC coils...it shuts off the system if the primary drain system malfunctions and water starts to collect in the overflow pan/drain system. After I sent the post, then figured that what it was. See below question. R - Red wire to thermostat and wet switch (red wire) C - Red wire to thermostat 2 wires of wet switch (Green Black) Additional orange wire from the wet switch goes to a red wire that goes to the outside AC compressor. Is there 4 wire total on this switch? Have any info on this switch? Where is the white wire from outside go to? The reason I am asking is that I find it odd that the switch is wired between R and C, and if it close, it will short out and burn out the transformer or fuse (if it has one on the board) Originally Posted by Jay11J Is there 4 wire total on this switch? Have any info on this switch? Where is the white wire from outside go to? The reason I am asking is that I find it odd that the switch is wired between R and C, and if it close, it will short out and burn out the transformer or fuse (if it has one on the board) I didn't install the wet switch myself, my HVAC service guy did...I'll post a couple of pics to see if that helps. There are 5 wires coming from the wet switch (gray wire bundle at the bottom center of the picture): Black and Green are wired together and then to C on heater Red goes to R on heater Orange goes to a red wire which goes outside to compressor White is not used On the right side of the picture by the wire nut is the brown bundle that goes outside to the compressor. Only 2 wires are used: Yellow goes to Y on heater Red goes to the orange wire on wet switch Thanks for trying to sort this out for me...I decided not to try the Test function of the wet switch if it might fry the transformer. Oops, I guess I'm not allowed to post attachments yet, so no pictures. Send me your email in a PM and I'll email you the 2 pictures, one of the wet switch and one of the wiring. Thanks. I did find a link to the installation instructions from the switch manufacturer: http://www.diversitech.com/applicati...t%20Switch.pdf Maybe this note at the bottom of the first page of instructions is indicating what he did...when the switch gets wet the compressor stops running: CONTROLLING SELECTED COMPONENTS To stop selected components of a system such as compressors, electric valves, condenser pumps, chill water pumps or other 24VAC controls, wire the wet switch to break the common to just that control. Ok, I looked at the manual, and it is wired up right. The switch is a Solid State control with a LED light, so that's why it has all these wires and wired to Common. Yours is wired up to shut down the unit outside if there was water in the pan. Thanks a bunch Jay, I appreciate your assistance. I just ordered the new stat, I'll hook it up as soon as it arrives. Glad to help. Honeywell did a very good job with these stats. I used to have the VisionPro for about 2 years, then upgraded to the IAQ 2 years ago.
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