Here's what to ask for...
- Line voltage thermostat,
- mechanical non-programmable,
- switch-type SPST,
- switch action close-on-rise.
"Line voltage" as the fan is probably 120vac. SPST. Single switch, on and off.
It's actually a cooling stat. The switch will close on temp rise as if to turn on a cooling fan on temp rise. Think: it's trying to cool the fireplace. Actually, it's blowing the hot air into the living space. Fire goes out; temp drops below preset (90); fan goes off.
Needs to be installed by an electrician. Easy.
For more information:
Read Lee Hall's Q&A "What is the greenest, best fireplace replacement?"