Gun-shy with Thermostats, could use some expert advice


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Old 06-14-14, 06:07 PM
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Gun-shy with Thermostats, could use some expert advice

Just discovered this site and posted something piggy-backing on someone else's thread but think I should ask my question in a new thread. So here goes...

Backstory: Two years ago, I attempted to install a programable thermostat in my new home from another property of mine. Thought I did everything right and could never get the A/C to respond. Took photos before I started so that I could put everything back the way I had it and somehow still screwed it up. Had to call a professional and paid $159 for ten minutes work. Still mad at myself.


Flash forward to now. My wife was given a programmable thermostat from a co-worked. We have two units, one for each floor and they're identical models. We are on a peak-usage energy plan and I want to have programmable option so I thought I would give this a shot.

Existing model: Honeywell T8411R

New model: Honeywell RTH7500D

I again took photos to save myself if my project didn't work out. I was able to get it powered up but it was blowing warm air when it was supposed to run A/C. Trouble-shooted, no luck. Went back to the old unit and just tried to just reset things the way they were. Again, thermostats proved to be my Achilles heel and I wasted about two hours trying to get it back up and running. Still don't know what I was screwing up but at first it too was blowing warm air instead of cold but alas I finally got things back to the way they were.


Below is a photo of the current wiring on my T8411R and the unwired unit to see if you guys think I can get this thing working or if it's incompatible. I think you can see but in the event you cannot, the T8411R has a jumper W1 and Y.


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Appreciate any and all feedback.
 

Last edited by PJmax; 06-14-14 at 07:15 PM. Reason: Cleaned up/reoriented pictures
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Old 06-14-14, 07:27 PM
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Welcome to the forums.

This is your thread for your thermostats. Your post is no longer in the other thread. Two threads on the same project gets confusing quickly.

I'm sure we can get you going here. I saved the pic of your old wiring from the other thread and put it here. Your old wiring looks a little strange. It looks like the white and orange are reversed. Is that exactly as it was originally ?

When you tried the new thermostat..... did you go in and program it for heatpump operation ?
Most likely not which is why is was blowing hot air.
 
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Old 06-14-14, 09:49 PM
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Based on what you copied over here when consolidating, what you see in the top two photos is the two current (identical) T8411R thermostats we currently use. The one on the right is the downstairs unit (that I am not trying to replace but wanted to show because it's a cleaner view). You can see it has a jumper connecting the W1 and Y connections. The one on the left is the upstairs unit with identical wiring, it just looks sloppy and the yellow wire is snaked through the W1 and Y. This wiring is performing correctly.

When I attempted hooking up the new unit, I did not program for heat pump. Frankly, I didn't know I could do that. I will have to try to find an owners manual (remember this was given to us by a coworker). I tried a number of configurations but some connections were obvious:

Blue - C
Green - G
Red - R and later tried coupling with RC/R
Yellow - Y and later tried coupling with Y/W or (O/B)
Orange - tried W2 bc of previous wiring but also tried connecting to the W pr (O/B) after uncoupling it from yellow
White - at one point tried the W (O/B) connection and when I move the orange to the W (O/B) connection I tried it on W2 for lack of other ideas
 
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Old 06-14-14, 10:15 PM
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Here's the link for your thermostat manual.
customer/honeywell/thermostat manual.pdf

I'm pretty sure Step 170 needs to be set for 9.

Houston will stop by and fill in the rest of the programming changes.
 
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Old 06-15-14, 07:19 AM
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My company has a tech that will never use the orange wire for the O terminal.
Looks like he isn't the only one that does this.

Y = yellow ( no jumper)
Aux & E = orange
Rc & R = red
G = green
O/B = white
C = blue

Set function170 to 7
190 =0
 
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Old 06-15-14, 08:35 AM
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Thanks for clarifying Houston. I saw the W and W1 and was thinking two heat stages.
 
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Old 06-15-14, 08:43 AM
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It is 2 stages of heat but since we have an O terminal to control a reversing valve in use it is a heat pump with Aux (stage 2) heat.
 
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Old 06-16-14, 09:29 AM
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Thank you so much guys. I took yesterday off but followed your advice this morning and have the cold air flowing. I appreciate very much both of your responses. I followed the wiring advice given and programmed it as you prescribed and all appears well. Now I just have to program it. Thanks again!
 
 

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