Taco ZVC404-EXP Problems

Discussion in 'HVAC Heating & Cooling' started by mjenergy, Jul 15, 2013.

  1. mjenergy

    mjenergy New Member

    Messages:
    1
    Location:
    Breckenridge, CO
    My 8 Zone radiant floor heating system is controlled by 2 Taco ZVC404-EXP Controllers. One is the Master and the other one is the Slave. The system is 3 1/2 years old and has been working fine up until last week. I noticed that some of the zones were not heating properly. After further inspection here is what I found:

    Master: Zone 1 is not working properly. When Zone 1 calls for heat, the boiler starts, the zone valve opens, but the circulating pump does not run. When zone 2, 3 or 4 call for heat, the boiler starts, the zone valve opens and the circulating pump starts running (they are working properly).

    Slave: Zones 2, 3 & 4 are not working properly. When Zone 2, 3 or 4 calls for heat, the boiler starts, the zone valve opens, but the circulating pump does not run. Zone 1 is working properly. When zone 1 calls for heat, the boiler starts, the zone valve open and the circulating pump starts running.

    Are both controllers bad and need to be replaced? Thanks for your help.

    Mark
Similar Threads: Taco ZVC404-EXP
Forum Title Date
HVAC Heating & Cooling Taco Check Valve Chatter Dec 14, 2012
HVAC Heating & Cooling Issue with Taco 241 swet-check Jan 19, 2009
HVAC Heating & Cooling Taco Zone Valve Dec 29, 2008
HVAC Heating & Cooling are the Taco F4 and F5 compatible? Dec 7, 2008
HVAC Heating & Cooling Wiring a taco zvc404 Nov 21, 2008

Share This Page