Help with Nest Thermostat, power connector, and Taco Sentry Valve

ThermoRookie

I have five heating zones in my house. 4 are controlled by Taco sweat Zone valves, and the 5th is controlled by a Taco Sentry Zone Valve.

The Taco sweat zone valve have three wires - green, white, and red.

While the Taco Sentry Valve has four: white and red on the left, and white and red on the right.

I have 4 Nest Thermostat E that have been connected and working without any issues for about five years connected to the 4 Taco Sweat Zone valves, without a C-wire.

We recently added the 5th zone when we finished our basement. The contractors put in the Taco Sentry Zone Valve and a cheap thermostat which I replaced with the Google Nest Thermostat and got a nest power connector since it wouldn't work because I didn't have a C-wire in this zone.

I followed the installation diagram as best as I could for a heat only system, since this is what I have.

I have a red and a white wire on the Thermostat end, which I connected to the grey (W/Y and R) of the nest power controller.

I connected the C wire of the nest power controller to the R wire attached to the C (further to the right) of the Taco Zone Sentry Valve.

I connected the W/Y from the nest power controller to the same Bundle from #1 (green wires) of the other 4 Taco sweat Zone Valve.

and I connected the R from the nest power controller to the same Bundle from #2 (white wires) of the other 4 Taco sweat Zone Valve.

I'm still getting the N260 error when I configured the New Nest Thermostat and when I raise the temperature setting it does not turn the zone on.

Please help me by letting me know where I went wrong with the wiring and which is the proper way to wire it.

pecmsg

you’ll know my views on NEST

EdTheHeaterMan

pecmsg said:

you’ll know my views on NEST

He is actually a secret admirer. LOL

However, your problem may be with the fact that you are connecting the wires in the incorrect place. As soon as you start to connect to a common wire for any thermostat the factory diagram for the zone valve must be carefully observed. When you connect a 2 wire thermostat to T T on a control or zone valve or transformer. The R on the thermostat can be placed on either of the T terminals or wires. The W on the thermostat can be connected to the other T or the transformer or other terminal or wire designated by the control or zone valve manufacturer instructions. That is because the R and W on a thermostat are just two ends of a switch.

When you add the C wire to the mix, then the T T on the control is not longer just a T T/ one of the T from the control must be considered an R terminal to line up with the C terminal of the transformer you are using to control that circuit. The other T terminal then becomes the W terminal. Since many controls were designed to work with a two wire thermostat, the instructions rarely let you know which one is the R and which one is the W. Newer controls will have those terminals differentiated.

I have some illustrations that will help. And I want to add that electricity is colorblind. The fact that a red wire and a white wire is connected to a zone valve does not help to determine whether it is a R or a W or a C or any other terminal. So, to be more helpful, can you post a picture of the wires on the zone valves, all 5 of them? And also a picture of the transformer the zone valves are connected to. There may be more than one.

My illustrations will follow soon.

EdTheHeaterMan

When you connect a 2 wire thermostat to T T on a control or zone valve or transformer. The R on the thermostat can be placed on either of the T terminals or wires. The W on the thermostat can be connected to the other T or the transformer or other terminal or wire designated by the control or zone valve manufacturer instructions. That is because the R and W on a thermostat are just two ends of a switch.

When you add the C wire to the mix, then the T T on the control is not longer just a T T. One of the T from the control must be considered an R terminal to line up with the C terminal of the transformer you are using to control that circuit. The other T terminal then becomes the W terminal. Since many controls were designed to work with a two wire thermostat, the instructions rarely let you know which one is the R and which one is the W. Newer controls will have those terminals differentiated.
So, to be more helpful, can you post a picture of the wires on the zone valves, all 5 of them? And also a picture of the transformer the zone valves are connected to. There may be more than one.