CamStat requires 24VAC but I've only got 2 wires

[Ericryherd]

I guess I didn't read up enough on CAMSTat. I assumed that I could simply replace my simple mercury switch thermostat with a CamStat and it would steal enough power to run off of the wires even when the switch is closed. THat's how my programmable thermostat works (which also uses a single AAA battery to remember the programming even when power goes out).

But the CamStat requires a minmum of 4 wires - 2 for 24VAC and 2 for the switch. Unfortunately, I've only got 2 wires.

One of my thermostats (I've got 5 zones) is relatively easily accesible so I can install the CamStat there with the 4 wires. I'll get around to that isntall eventually but now it's a pretty low priority due to the complexity.

Does anyone know of a simple wireless thermostat that can power itself off of the switch power and store enough charge so that when the switch is closed it still works???

Eric

[Stuart]

Eric,
I had the same problem. I ran a separate 24v line to the thermostat and then ran a 24v relay off the unit. Then wires the two wires from the furnace to the relay. The thermostat output wires have the same 24v as the voltage feeding it. You've got to be careful or you can fry the controls. Since the unit doesnt have a battery it needs to have 24v all the time. I have a second unit and whenever I get a chance, I'm going to perform surgery on it and at least try to isolate the relay contacts.
Stuart