TACO ZVC 406 - Coupled zones?

jholivier

I have a TACO ZVC 406 controller - hydronic radiant heat.
The issue I am facing is the following:
When the thermostat associated with zone 4 calls for heat, the T-stat and valve lights on the controller do not turn on unless zone 3 has already been activated (T-stats and valve lights on) with its associated thermostat. In other words, if zone 3 is on, zone 4 works perfectly. This observation makes me believe the zones are somewhat coupled—the same issue with zone 2 and zone 5. Zone 2 needs to be on for zone 5 to operate.
All zones work perfectly, but this weird association between zones makes them not operate individually.
Any thoughts?

SteveSan

@jholivier Please give us a call at 401-942-8000 and ask for Technical Services. We are here until 5pm EST.

jholivier

Thanks, Steve, I Already called your Technical Services, but the tech had no idea where this coming from.

SteveSan

Please call and ask for myself, Steve in Tech Services

dko

Can start with a photo of the ZVC panel wiring and what kind of thermostats

jholivier

Thank you DKO, I will post this tonight!

dko

jholivier said:

Thank you DKO, I will post this tonight!

I would call Steve first and foremost

SteveSan

@dko we did talk on the phone and supplied all my contact information. Unfortunately jholivier wasn't home at the time. Gave him some troubleshooting tips and to contact if any questions.

jholivier

Hi Everyone,

Thanks to Steve, I was able to resolve the issue. I am posting what I did:

As suggested by Steve, I jumped the R and W on the zones that seemed to be associated with other zones. When jumped, both zones worked independently as they were supposed to. This led me to believe it was a wiring between the thermostats and the zone on the TACO controller. While a former owner or contractor labeled the W wires for each zone with stickers (in the TACO box), the R wires (coming from the thermostat) were not. This led me to the hypothesis that the R wires were ill-connected. Knowing that a Voltage of ~ 25V exists between the R and W for each zone on the controller, I disconnected all the R and W wires and troubleshooted each zone separately by only connecting the W and R wire for that specific zone on the TACO controller. I then went to the thermostat corresponding to that zone to check the incoming voltage (between the R and W). If the wiring was correct, the voltage reading should be 25V. Of course, if the R wire was incorrect on the TACO controller, no voltage could be read on the specific thermostat I was troubleshooting. Using this workflow, I re-wired all the thermostats independently. Every zone works fine and independently from each other.

I am far from an expert, but it seems that my thought process was appropriate and made sense.

I am happy to hear your thoughts.

SteveSan

Glad I was able to help. Enjoy the rest of your day.