I'm new to dealing with home wiring, and have done several hours of research, but can't quite find the information I'm looking for. I have an old--ie T/T, no individual common terminals for each thermostat--Taco SR506 hooked up to my boiler, with 5 zones configured. Heat only, no AC.
I don't want to try to run 5 NESTs with no common wire, so rather than setting up individual (ie plug-in) transformers at the thermostat end for all 5, I wanted to set one up on the boiler side, and run a common wire to each thermostat.
The SR506 has a 24V 15VA transformer with a common terminal that I could theoretically use.
However, from my research, that is enough to power 1 NEST, but not 5 (in a couple posts here, it seems like a 24v 40VA transformer can run 2). It seems that even if it had individual common terminals for each thermostat, the problem would remain the same--the built-in transformer couldn't power that many NESTs anyway. As such, I was looking at some 24V ~100VA transformers to wire up instead--for example:
This is where I'm stuck--I'm not sure where to go from here. Getting the common wires seems easy--use the yellow transformer output to a 6 conductor push wire connector, and use the other 5 conductors to run the common wires to each thermostat. But...the on-board transformer is still responsible for the main power to each thermostat--which it couldn't handle--right? Could I just do the same type of thing for the red wires for each thermostat? IE use the yellow/white transformer output to a 6 conductor push wire connector, then steal the red wire from each thermostat terminal on the SR506, and run them to the push wire connector? Or would the fact that the SR506 no longer had any power outputs to the thermostats break everything? I suppose I could try this with a zone I didn't care about or use very often...but getting some help up-front would be great.
Please forgive me if my terminology is off, or if this question is too basic. While I have a mechanical engineering degree and have no problem messing with machines and trial-and-erroring my way through things I have no experience with, I've managed to avoid wiring my entire life until now, and just don't have enough knowledge to feel comfortable (enough) to try this yet. That said, I'd like to avoid paying an electrician if I can