I have an oil fired forced air furnace with a Honeywell R8184 1296 ignition control. It only has two poles for the thermostat connection. I bought a 24v thermostat that requires a 24v com. The thermostat cable has a third wire available. But where do I get the common from without replacing the control? Can I just put in a 24v transformer and just use the common side?
This is for a cabin that is not used a lot. The new thermostat will alow me to control the temp by telephone.

In case anyone is curious, here's how I solved the problem. I used a 24v transformer to power the thermostat connecter to r and c. There was a jumper for a millivolt system that isolates it from the 24v. Connected thermostat wires from furnace to w1 and mil.