Hey gets,
hoping your can help me out with an installation issue with a nest thermostat,
the goal
standalone boiler/radiators with Rh C and W wires.
Central ac with Rc C Y G wires
standalone humidity located in attic near air handler.
I have a rib relay (typical go relay 24 volt coil, spst action)
The goal: proper heat operation, proper AC operation, dehumidification to output G and *.
I get a 24 volt output on G wire but only 13 volt AC on *. Will not activate the relay. Wiring is brand new, I switched to a spare conductor with same result. I get the teardrop on the screen, I have the settings for srandalone dehumidifier, turn AC fan on (G) with a call for dehumidifier.
There is a very small amount of information regarding C wire, pros and cons or requirements, or even how they or if they matter which transformer they are coming from. It’s not well documented.
I read that the Heat W1, W2, terminals and * and maybe o/b ( I forgot) operate from Rh …obviously that makes sense for the heat terminals but can this,be a problem for a dehumidifier…
whereas Rc is attached to cooling terminals Y1,Y2, and fan G
questinos
why am I unable to get 24 VAC out of * terminal setup and installed as above.
what is the bottom line on C terminal functionality or limitations or quirks….where does the C best come from in various two transformer applications.
PS. I have to say the nest main install pdf 37 pages I believe, is excellent…..but of course, understandably does not get into two transformer systems.
Thank you In advance for your help
Jon K. Owner 32 years HVAC
