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