I have purchased and installed two Honeywell digital programmable thermostats that are connected to two Auto Mag low voltage zone controllers. They have not worked from the day I installed them. Too much heat as if the thermostat did not recognize the actual air temperature. An electrician told me that the Auto Mag controllers will not work with digital t'stats without a special interface. He did not know what that interface is. Can anyone help with this frustrating problem?

GWH

I have done some work on the zone valves of the heating system of my church. They require a positive signal to shut off the heat. Others here have reported furnaces that worked that way. To start a heat cycle, thermostats switch power from a transformer to a wire connecting to the gas valve, zone valve, etc. In most cases, breaking the circuit shuts the heat off. In some systems including my church's zone valves, power must be applied to another wire. That can be done with a double throw relay. In that case the usually a white wire powers the relay coil. When energized, it applies power to the valve opening it. Once open, the valve shuts itself off and stays open until the relay coil loses power switching power to a different contact on the valve actuator. It then closes, and shuts its self off. It really isn't as bad as it sounds. All you may need is a relay for each controller. Your electrician friend should know all about double throw relays.

What you actually need is a SPDT thermostat, like the old Honeywell mercury T87 series. I'd suggest you call Jim, the owner of Automag. He can suggest a couple different digital thermostats. I think the ones he suggests using are programmable but you really don't have to use that feature. You can get the phone number from the Automag web-site.