Taco ZVC-EXP problem

Alan (California Radiant) Forbes

I have a ZVC 406-EXP daisy chanied together with two ZVC 404-EXP's via their expansion connections. The 406 controls staple-up, priority DHW and the Master-Slave switch is set to Master. One of the 404's controls radiators and its end switch is wired to a pump serving the radiator zones. The other 404 controls the basement radiant slab, its end switch is wired to the pump serving radiant and both both 404's are set to Slave. The problem we are having is that whenever a zone on the 406 calls for heat, the end switches on both 404's close and the pumps turn on. I thought that even though they were all communicating together, the end switches would only close on a call from one of its own zones, no?

Paul48

Output

When that happens are you actually getting a 24V output from the 404s to the zone valves? You are letting the 404s control the circulator from their connections, and not switching directly through the end switches?

Paul48

Output

Duplicate

Alan (California Radiant) Forbes

ZVC

Paul:



None of the 404 zones are calling for heat, so there is no voltage going to the zone valves.



Each 404 controls its own pump through the end switch.

icesailor

Somewhere:

There is somewhere.

You need to pull wires until the circulator (s) stop. Then, start over.

Alan (California Radiant) Forbes

10-4 icesailor

I just wanted to make sure that since they are daisy-chained together, that a call for heat on the 406 is not intended to close an end switch on the 404's.



Thanks for your and everyone else's help.

Paul48

Double-check

the expansion wiring. Make sure you haven't flip-flopped a wire. And don't bite my head off! You have a "stupid" problem, that requires a certain amount of stupidity to solve.

icesailor

Taco End Switches:

You can connect every end switch together and have each and every head activate the control and not know it.

It is not my experience that most electricians are experts in control wiring. That if there is a problem, we who do this have the best chance of fixing it. At least we understand what is trying to be done.