This is the way I have it wired from the TEKMAR to the zone valve to the oil burner aquastat: Tekmar: Zone Valve: Aquastat: Red -------------------------------------------- Blue------------------------------------------Red Black-------------------------------------------Brown Black-----------------------------------------Black I reversed the wires on the zone valve and tried: Tekmar: Zone Valve: Aquastat: Red -------------------------------------------- Blue------------------------------------------Red Brown-----------------------------------------Black Black-------------------------------------------Black This gives the exact same results. I attached the actuator product information. Thanks again, Bob