Hooking up a nest power connector to triple aquastat

snackman1973

Tried many different combinations,  after reading the C wire was common and needed to be grounded,  I attached to the side of the box.  Still doesn't function.  The 2 thermostat wires coming out of the unit are green and white(pretty sure whoever hooked it up originally just used the green instead of the red bc the red isn't connected to anything up at the weird junction box that I've never seen before.  Hopefully someone has seen something similar in their travels

It's an oil burning system with baseboard heat

HVACNUT

You're not getting 24 volts out of the aquastat. That part shouldn't get touched anyway. 
What's the va rating on the external transformer? You might need a 50 va.
You need 3 wires at the thermostat. R,W,C. 

109A_5

Hello @snackman1973,
Bonding the C wire to the equipment ground is kind of irrelevant for proper operation. The external transformer size may have to be increased to handle the extra load of the NEST thermostats.

Are you using the C wire adapter box thing ? If so do you actually need it ?
If not I would wire it this way.



If you wanted to clean up the wire colors a bit.

109A_5

Hello @snackman1973,

With NEST Power Connector. Just one NEST or all three zones ?

STEVEusaPA

I bet @Robert O'Brien knows a way!
Can’t find his article, but an AC Ready or Kool Kit w/transformer would easily work.
Use that for your common, run 2 wires to T-T to close the aquastat switch.
Edit: Found it.
https://heatinghelp.com/systems-help-center/what-to-do-if-you-dont-have-a-c-wire-for-your-thermostat/

HomerJSmith

If you have three wires (conductors) to the Nest, do it exactly as 109A_5 diagrammed in his first post and forget the adapter. You will need an aux transformer, 40VA-24Vac.
The connections from the Taco zone valves to the aquastat is the same as before the Nests were installed.

Alan (California Radiant) Forbes

Make it easy for yourself for wiring, easily available "C" connector and diagnostics. Use one of these below. The Taco ZVC405 and 406 and the Caleffi ZVR106 all have 80 VA transformers.