We are having a power outage in much of Los Angeles right now, big storm (02/17/17 3:55PM). I have a gas wall heater, pilot is lit, but no power to the wall thermostat. Can I turn on the unit manually to get heat?
When you have time, do this to trouble shoot this heater. This gas valve is powered by a pilot generator. If you have a volt meter follow the 2 wires from the pilot to where they connect. check the output voltage on these wires. The voltage should be about 3/4 volts DC. If you get the 3/4 volts dc, disconnect the wires. Did the pilot go out? If it did relight the pilot. this proves that the pilot generator is working. Next, if the gas valve does not click when the thermostat is turned up and down, put a jumper wire on the control circuit. If the gas valve clicks the problem is in the control circuit. You stated earlier that the gas valve clicked when you jumped out the control circuit. If the valve clicked but the gas did not light, you may have a spider web in the orfice of the gas input line at the burner. You will need to take out the burner remove the gas orfice from the gas pipe at the burner and clean it out. reassembly and retry the heater. Spiders in gas orfices are rare but they do happen. I know I have cleaned out a few. They crawl in when the heater is off for an extended period of time.
Gas Empire-style wall heaters use millivolt thermostats. They have two wires going to the thermostat, and if those wires are connected to each other, that is a "call for heat" and the heater should fire.
So, you have a system that requires AC power? Either it's not an Empire-style millivolt system... or somebody's hacked it in some weird way, e.g. to use a Nest style thermostat.
If they hack it like that, they should connect the new relay/whatever/thing in parallel with the original thermostat, and leave that in place for just this contingency.
Northeasterners/Midwesterners: This type of system is nothing like anything you know. It is a closely held secret by Floridians, Pacific Coasters, and the northeastern HVAC cartels, and at this point, my job is to convince you that it doesn't exist. Furnaces that can work on gas alone, without electricity? Absurd. Just ask your HVAC distributor. These aren't the heaters you're looking for. You can go about your business. Move along.