We have these White Rogers, F19-0187 zone valve installed. Got to the church today to find a cold finance room and upon investigation the thermostat wires on pins 5 and 6 were again lose. We constantly have connection problems with these valves.

What is the preferred gauge size for these valves? We're using standard, brown thermostat wire which I believe is 18/2 but what does White Rogers recommend be used with these valves? I understand these were popular back in the day but I can't see why with these constant connection problems.

Also, the valves don't always completely close. This causes a zone to run hot. Lastly is there a way to tell by looking at the valve if it's in the opened or closed position? I know how to tell when it's in manual but I'm talking about when it's in the auto position, can you tell if's it's opening or not (other than feeling the pipes)?

I'm thinking maybe we need to rewire with the correct wire size...