[Osage Orange]

I found that the exhaust manifold heater is far more effective - and brings the heat sooner - than the hot water heater in a Model A. Since the early Fords didn't have a pressurized system, the hot water never got as hot as needed in the winter simply because the radiator worked quite well cooling the engine water when it was cold out. Exhaust heaters were the opposite: The more you ran the engine, the hotter they got.