Nest C wire connection to carrier weathermaker.


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Old 07-21-17, 08:18 PM
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Nest C wire connection to carrier weathermaker.

I have nest 3rd gens connected to carrier two zone weathermakers. I have 4 wires from old thermostats. Y,W,Rh and G. It's been working but the fan runs sometimes when the units aren't calling. I've been told it needs a c wire connection. There are spare wires. Can I simply connect the c from the nest to the c on the zone controller? The nest agents said it needed to be done by a professional to make sure it was grounded. There are two zones and the controller only seems to have one zone that has a G position. Even though both thermostats have G wires connected. Thanks for any info.
 
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Old 07-21-17, 08:22 PM
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Welcome to the forums.

You can get the C connection from the zone control board.
It may be grounded... it may not be..... but it doesn't have to be grounded.


Before you make any changes..... did the Zone 1 thermostat have a mechanical HEAT/OFF/COOL slider on it ?

Sometimes the zone 1 thermostat sets the system parameters mechanically.
 
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Old 07-22-17, 03:39 AM
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Thanks. Yes it did and also a fan slider. They were old style round dial Honeywell mercurial switches. If it helps the system was around 18 years old. Original to the house. I could post a photo of one of the zone controllers if it helps. I don't think it would make a difference but there are two of these systems in the house. One in attic and one in basement. Both are dual zone and seems both have similar symptoms of uncalled for fan running.

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Last edited by PJmax; 07-22-17 at 04:17 PM. Reason: added pic from link
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Old 07-22-17, 11:43 AM
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I need to check further or wait for my forum partner Houston to reply to see if the Zone 1 stat can be changed to electronic.
 
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Old 07-22-17, 03:07 PM
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trying this again.

https://*******/fkQ1kQ
 
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Old 07-22-17, 04:20 PM
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I swapped your photobucket pic with the ibb one.

I know what you have. I just need to go back thru the install manual. I haven't worked with many of these older zoning systems like my partner has.

With the older ones..... the slide control locked the system into COOL or HEAT mechanically. Now you want to do it electronically. That's where the gray area is.
 
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Old 07-22-17, 08:57 PM
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Yes, I have installed many of those weathermaker 2 zone control boards.
You can install your new stats without an issue created by the zone control board.

Only zone 1 gives you the Fan only option.

I recommend adding the C wire with any Nest installation.
 
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Old 07-22-17, 09:09 PM
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Thanks for the reply. So, I just connect the c from the bottom left of the control board to the thermostat? The nest folks said I had to be careful regarding the grounding of the c-wire? Does that sound familiar? Or is it just as simple as running the wire? thanks
 
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Old 07-22-17, 09:09 PM
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Thanks for the heads up Houston.

In some systems the C will be grounded already. If it's not it shouldn't present a problem to the nest operation.
 
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Old 07-24-17, 06:47 AM
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Thanks for the help. I wired up the two thermostats downstairs and all seemed to go ok. The nest read it as a 24v connection and the unit is still functioning. I haven't noticed any aberrant fan running yet. I will connect the upstairs today. Thanks!
 
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Old 08-06-17, 05:44 AM
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Happy to report everything seems to be running well. No longer have phantom fan running. Wondering if anyone has any idea how much electricity I may have wasted not having the c-wire hooked up before? Seems this would have been considered very inefficient and that Nest shouldn't have recommended using it without yet they said it was fine. Thanks for all your help. Wish it hadn't taken me so long to realize the problem.
 
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Old 08-06-17, 01:44 PM
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Wondering if anyone has any idea how much electricity I may have wasted
That would require multiple guesses.

It's not only nest. Many power stealing stats have similar issue. That's one reason why nest recommends a professional installer when the install is not a common one like in the case of the zoning system.
 
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Old 07-24-18, 03:22 PM
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Weathermaker control board info

Hi, I noticed you installed the Nest to the Carrier Weathermaker control board. I need to upgrade to that controller board in order to be able to connect the Nest like you did. Can you tell me that exact name and model number of that control board so I can search the internet for it?
 
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Old 07-24-18, 05:21 PM
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Welcome to the forums.

That Carrier board is pretty old. Not sure I'd call it an upgrade. What are you "upgrading" from ?
The Carrier part is a CEPL-1SI...... CEPL-1SI.pdf
 
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Old 07-28-18, 03:05 PM
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That Carrier zone control board will send a timed signal to the motorized damper to open or close. Most dampers will spring open unless they have a signal to close.

You would only want to Install that zone control board with power open/power closed dampers.

I like the fact that Carrier zone systems can modulate the closed dampers to the open position if the Leaving Air Temperature Sensor detects air that is near freezing or too hot.
 
 

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