New Honeywell Thermostat runs both Heat and Cool


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Old 06-05-14, 11:07 AM
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New Honeywell Thermostat runs both Heat and Cool at Same Time!

I recently purchased a new home and replaced the old Honeywell Chronotherm with a new Honeywell thermostat (Model #: RTH7400D1008). The house has a boiler and an evap cooler. Under the old system, the evap cooler won't turn on until the thermostat is switched to "Cool."

I labeled the old wire connections from the Chronotherm (W, Y, Rh, O) to the new thermostat (Aux/E, Y, R, O/B) and played with the different advanced heat pump settings and others. Each time when the swamp kicks on, the heat kicks on as well. I've even tried to remove the W-wire entirely and the situation remains the same.

I've emailed Honeywell's support a couple days ago, but haven't heard back. Need to get this squared away or the old Chronotherm is coming back! Thanks.
 
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Old 06-05-14, 12:53 PM
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Can you give us a little more information?

Post the Old stat terminal = color = new stat terminal combination used.
Post the function 170 = ? number that you are using.
 
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Old 06-05-14, 01:49 PM
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My apologies, I don't know exactly what you're requesting. The wiring doesn't seem to follow a traditional color scheme - four wires - two red, two white. All I have to work from are the labels from the old Chronotherm to the new Honeywell. So, I've tried matching the old W, Y, Rh, O to Aux/E, Y, R, O/B.

Not sure what you mean by function 170. Thanks for your review.
 
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Old 06-05-14, 03:07 PM
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It is strange that you were using an O (heat pump) terminal on the old stat. The O terminal is energized the entire time you are in cooling mode regardless of an actual cooling demand.

I would have expected G instead. G is energized when you have a fan operation demand.


I see that you are referring to heat pump terminals on the new stat. The heat pump terminals will have different functions with the factory default setting for function 170 (which is 1)

If you actually want the O/B terminal to operate as an O terminal the thermostat function 170 must be changed.

http://i151.photobucket.com/albums/s...00heatpump.jpg
 
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Old 06-06-14, 10:25 AM
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I've updated the advanced settings to reflect a heat pump and played around with those settings to no avail. I'll take another shot at putting the O wire into G, but I'm pretty sure that didn't work when I originally tried it.
 
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Old 06-06-14, 11:03 AM
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You have two cables with a red and white wire in each cable. The cable that goes to the boiler should connect to Rh and W. The cable that goes to your swamp cooler should connect to Rc and G. The Rh-Rc jumper needs to be removed.

Set the thermostat to standard (non heatpump) setting.
 
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Old 06-06-14, 03:00 PM
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Thanks, all.
Here is my old Chronotherm wiring (missing screws equal wires).
Name:  Chronotherm.jpg
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Here is my new wiring:
Name:  New stat.jpg
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When I get home tonight, I'll try Rh, W, Rc, G.
 
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Old 06-06-14, 04:57 PM
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Just curious where did you find those terminals on a RTH7400D1008 ,I just checked the Installation manuals and didn't see Aux/E O/B
Geo
 
 

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