Well, it isn't really that cold outside in my area. But I am getting used to the climate here and 55 seems cold.
Cabin Heating is supplied via a shroud around the engine exhaust system. This allows air which is entered from an inlet in the rear engine baffles inside the cowling to be warmed by the exhaust pipes, it can then be directed to outlets into the cabin (see your planes manual for those). The system is very effective once the engine is warm, although its use is governed by a couple of safety factors.
Firstly the heating system effectively opens a path through the firewall between the engine compartment and the cockpit. For this reason the cabin heat is selected off before engine start OR if fire is suspected in the engine compartment.
Secondly with a system of this type there is a danger of Carbon Monoxide being introduced into the cabin. Use caution and buy one of those Carbon Monoxide stickers, money well spent.
