Adding Nest Power Connectors to TACO zone controllers


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Old 04-13-22, 09:55 AM
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Adding Nest Power Connectors to TACO zone controllers

I have a 4 zone heat only system and added nest thermostats. Getting regular power issue messages because I don't have a C wire on any of the thermostats.

Can I add the Power connectors to the Taco Valve or the junction box that seems to connect a couple of the valves?

Junction box that connects 3 of the zone valves


Zone valves, transformer and junction box


Zone vale current wiring
 

Last edited by PJmax; 04-14-22 at 01:03 AM. Reason: labeled pics
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Old 04-14-22, 01:12 AM
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Welcome to the forums.

The board default is to show "last 10 days". From the thermostatic forum index page.... scroll down until you see display options." Change "last 10 days" to "45 days" via drop down box. Then click "show threads." You'll see dozens of threads on this exact install. I just want you to see what's involved. All posts will be done in this thread.

In your first picture that is a 120v junction box. No connections for you there.
In the second pic I identified the valves with a letter as well as the two transformers.

In the third picture.... a working diagram. The valves have three numbers. I labeled the terminals and their functions. The system functions are labeled in yellow. They are specific and are not wire colors.

You would disconnect the thermostat wiring from terminal 1 and the R splice.
You would connect the thermostat wires to the dark gray nest adapter wires. No polarity here or at the stat.
The light gray adapter W wire goes to #1 terminal on the valve.
The light gray adapter C wire goes to the #2 terminal on the valve.
The light gray adapter R wires goes to the R splice where the white thermostat wire WAS connected.

This is the basic wiring. If you understand this.... the job is easy.
Problems in your system.... two transformers. That means the valves are most likely split between the two transformers. Don't get the wiring confused. Although it's a little more time consuming.... one valve should be done at a time.

Are there more than the four valves I see ?
 
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Old 04-14-22, 04:52 AM
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Hi, just curious, how many wires do you have at the thermostat locations? Look closely, there may be 1 tucked back in the wall.
Geo 🇺🇸
 
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Old 04-14-22, 03:16 PM
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Thanks. Pete. Yes, only four valves on system. This will be my project for the weekend and I'll post update asap.
Also, apologies for posting in incorrect location and I'll be sure to check out the other threads.

Geo us--the thermostats for heat have 2 wires, however I'll take another look to see if a third wire is buried.
The AC is a separate unit with it's own wiring and multiple wires. I added power connector to that already and it seems fine so far although I've only run to test; AC is not on for the season yet.

Rich
 
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Old 04-14-22, 03:23 PM
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Just checking.... you aren't connecting the heat to already wired nest thermostats on A/C.... correct ?
 
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Old 04-18-22, 10:54 AM
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Correct. A/C Nest not connected to any of the heating thermostats. All A/C connections are in attic. Heat is in basement.

I tested a power connector on the TACO value and got "No Power" on thermostat.
Here are my connections:
Thermostat wires to Power Connector:
Red to Dark Gray R
White (from transformer) to Dark Gray W

Light Gray Power Connector wires:
R to Transformer where W was connected
W to T1
C to T2

T3 --tested with Green wire (which looks like a jumper to other Taco valve) connected and disconnected
Not sure where the problem is.
 

Last edited by PJmax; 04-18-22 at 07:44 PM. Reason: labeled pic
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Old 04-18-22, 07:50 PM
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Just confirm your three light gray wires are in the correct place.
The order looks wrong in the picture but I can't see where they exit the adapter.

You'll see I added an R and C to the transformer.
The R goes to the adapter light gray R wire. The C goes to the center of the valve.
There should be two system wires on terminal 2 plus the light gray C wire.
Terminals 2 and 3 connect to 2 and 3 on the other valves for TT (boiler) control.

Is there a transformer for every valve ?
Typically 2-3 valves are on one transformer.
 
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Old 04-21-22, 11:32 AM
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Update

Yes, only 2 transformers for four valves. Checked and updated connections on Valve. "No Power" error gone, however now receiving N261 message.

I labeled adapter connections on Power Connector.

Thermostat wires to Power Connector:



Red to Dark Gray R

White (from transformer) to Dark Gray W

Light Gray Power Connector wires:

R from Transformer to Light Gray R wire.

W to T1

C to T2 with 2 system wires on terminal 2.

T3 -- connected to Valve #2 TT-3
 
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Old 04-21-22, 01:47 PM
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After you change wiring.... you need to restart the nest to learn new connections.
Everything that I can see looks ok.

There should be two wires on the transformer R.... one for each thermostat. (two zone valves)
Now you have the light gray R wire there but I don't see the other thermostat connected.
 
 

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