Mini-split instead of heater and A/C?

[Piwoslaw]

Since many cars already have A/C installed, could it be replaced by a mini-split heat pump? That way it could be used as a heater in the winter, heating the cabin before the engine warms up, and not robbing the engine of heat when it needs it most.

Also, wouldn't a heat pump be more efficient than resistance heating in an EV?

[tecrench]

Interesting .... AC compressor pulls a lot of HP and like in a home heat pump system, or an electric compressor like on the Prius. Also it would probably have to have electric strip heat (em heat) for those really cold mornings. overall saving $$ ???

[cujet]

Yes, a heat pump can use considerably less electrical power when compared to resistance heating. The performance ratio is called COP or co-efficient of performance. Generally, in moderate temps, heat pumps have a 3.0 to 4.0 COP (3 to 4 times less power use compared to resistance heating). However, using waste heat from the ICE when it's running, is always the most efficient use.

If you remember, the air cooled Volkswagens used exhaust to heat the cabin, just like today's small aircraft.

A combo setup could be very efficient. In fact, I see no reason why the electrically driven AC on a Prius could not be simply reversed and used as a heat pump.

[tasdrouille]

Using waste heat is most efficient indeed. However, waste heat (through the cooling system) doesn't come untill the engine is near full operating temp, which can take a while or forever depending on your engine or motor. Recent VW TDI have resistive heaters to provide instant heat. My older TDI could certainly use a heat pump, so do all electric cars. The problem is on convential engines, the cost/benefit ratio is way too small.

[cfg83]

cujet -

Originally Posted by cujet

Yes, a heat pump can use considerably less electrical power when compared to resistance heating. The performance ratio is called COP or co-efficient of performance. Generally, in moderate temps, heat pumps have a 3.0 to 4.0 COP (3 to 4 times less power use compared to resistance heating). However, using waste heat from the ICE when it's running, is always the most efficient use.

If you remember, the air cooled Volkswagens used exhaust to heat the cabin, just like today's small aircraft.

A combo setup could be very efficient. In fact, I see no reason why the electrically driven AC on a Prius could not be simply reversed and used as a heat pump.

I remember those. If you had a leak in your exhaust pipes the exhaust would enter the cabin. Don't get me wrong, I think it's a neat solution. At least you *knew* there was a leak and that you needed to fix it.

CarloSW2