The first thing that popped into my mind was a programmable thermostat
like I have in my house. Mine is a Hunter model that cost me about
$17. It is run on a single AA battery (or maybe it's AAA, I don't
remember). The temp can be set in either F or C and when the temp gets
1 degree below what is set then the unit switches on the furnace until
the temp is 1 degree above the set temp and then it turns off again.
Wouldn't be too difficult to remove the sensor to make it remote I
don't think.

Cheers,
Lawrence