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Nest Power connecter with Taco SR504

AndroiderΩ
Community Member

Hello friends,
I have two separate systems for heating and cooling.  Cooling is one zone AC; Heating is 5 zone gas powered boiler with baseboard.

I have 6 honeywell programable thermostats that I am in the process of replacing to Nest.  I have two Gen 3 learning, 1 Nest E and two Nest Thermostat.  I have eliminated one honeywell by combining heating and cooling into a single gen3 learning.  All remaining thermostats are heating only.

I am anticipating a "c wire" problem when I install Nest (non E, non learning).  I have a Nest power connector.  Need help from the community to avoid the "c wire" problem.

The 5 heating zones are controlled by a Taco SR 501 switch relay
Mfg manual -> https://www.tacocomfort.com/documents/FileLibrary/SR501-845RP102-105.pdf
reference -> https://cdn.shopify.com/s/files/1/0533/4922/0503/products/Taco-SR501-Switching-Relay_455x571.jpg?v=1...
Actual -> attached...

Here are my questions...
1 - W and R looks straightforward.  Is it sufficient to connect Nest Connector C to the empty COM port on top of the relay?  
2 - The thermostat where both independent systems are connected to gen3 learning has Y,Rh,G,W,RC wires.  Would adding a nest power connector to the heating system cause any issues with this thermostat?


 

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https://www.tacocomfort.com/documents/FileLibrary/SR501-845RP102-105.pdf

14 REPLIES 14

Houptee
Silver Product Expert
Silver Product Expert

If you can pull new 5 conductor cable to each tstat then you do not need the power adapters and just put RWC from Taco to RWC on Nest.

If you dont want to pull wire then you need a power adapter for each Nest

Except the one you already have working the Learning Nest it doesnt need one it gets power from the AC system.

To wire the power adapters you take off the R W from Taco and connect to R W on adapter.

Then the R W C outputs of the adapter go to the Taco R W C top screw terminals.


Houptee -- NJ Master HVAC Licensed Contractor

AndroiderΩ
Community Member

Awesome.  Thank you so much.  Will give it a try this week.

Since one with AC has Rh and Rc and the Rh is coming from the same taco, should I disconnect its Rh and let it get power from Rc?  

 

AndroiderΩ
Community Member

Also, do I need one nest power connector per thermostat?  I was hoping one would do for all 5.  

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@Houptee, thanks for the help!

 

@AndroiderΩ, how's it going with your Nest Thermostat? Still need our help?

 

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hey AndroiderΩ,

 

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do. 

 

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hi AndroiderΩ,

 

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

 

Thanks,

Edward

 

Thanks for checking.  I am not sure how to proceed.  Will try and post a detailed diagram and photos to seek additional help from this awesome group.

 

Houptee
Silver Product Expert
Silver Product Expert

Pull new thermostat wire to each Nest with 5 conductors in the cable otherwise you will need a separate power adapter for each Nest.


Houptee -- NJ Master HVAC Licensed Contractor

EdwardT
Community Specialist
Community Specialist

Hi folks,

 

@Houptee, thanks for the help!

 

@AndroiderΩ, I'm checking back in. Were you able to try the steps provided by Houptee? Keep us posted.

 

Thanks,

Edward

EdwardT
Community Specialist
Community Specialist

Hi AndroiderΩ, 

 

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do. 

 

Thanks,

Edward

 

aatienza
Community Specialist
Community Specialist

Hey there,

 

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
 

I appreciate the help, Edward.

 

Thanks,

Archie

Thanks for all the help and responses. I don't have any questions at this time.  

Jake
Community Specialist
Community Specialist

Hey there,

 

I am glad to hear everything is good to go from here. I am going to go ahead and lock the thread at this time. If you do have any questions in the future, please feel free to create a new post.

 

Best regards,

Jake

Houptee
Silver Product Expert
Silver Product Expert

You need one per thermostat because they each connect directly to the R and W of each Nest, then the adapter outputs to R  W  C to turn on each Taco

Leave the learning nest wired as it is. Do not put a power adapter on that one.  You have to keep Rh and W connected because the Nest is basically just a switch, it connects RH to W when the Nest calls for heat, and starts the circulator pump. 


Houptee -- NJ Master HVAC Licensed Contractor