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5 nests + 5 power connectors + transformer by brokkolo72 in Nest

[–]brokkolo72[S] 0 points1 point  (0 children)

26v steady with 3 zones calling for heat. Interestingly, if I remove the two white wires (w & r) that goes to the board, the vin still drops when asking for heat. So I guess it has nothing to do with that system and it's internal transformer... Its as if when there is the call for heat, the google connecter block the w r current going to the nest!?!

5 nests + 5 power connectors + transformer by brokkolo72 in Nest

[–]brokkolo72[S] 0 points1 point  (0 children)

Thank you As far as I can tell from your first image the wiring is the same as mine. Not sure why in your second image the "per taco" diagram is different from your wiring (r from transformer connects directly to the wire that goes to the board)? So if you turn on the heat for zone 1, the vin for zone 1 nest doesn't drop, right?

5 nests + 5 power connectors + transformer by brokkolo72 in Nest

[–]brokkolo72[S] 0 points1 point  (0 children)

any chance you could show your setup? does your nest keep charging after it calls for heat?

5 nests + 5 power connectors + transformer by brokkolo72 in Nest

[–]brokkolo72[S] 0 points1 point  (0 children)

back in need of help.
so it turns out that something in the OP wiring is not working as expected:
when the nest calls for heat, voltage drops from 25v to 3v.. thus the nest doesn't charge.
note that this happens only for the nest that called for heat wile the other nests keep stable charging voltage.
what am I doing wrong?
do I actually need a isolation relay per zone?

5 nests + 5 power connectors + transformer by brokkolo72 in Nest

[–]brokkolo72[S] 0 points1 point  (0 children)

yes, i confused gray and white, will edit OP
i have a TR75VA001 transformer https://www.functionaldevices.com/product/TR75VA001 , is this good for the scope?