Murton

Does anyone know how the heating works in the plug in hybrid?

From an efficiency perspective using the aircon system but running in reverse like a lot of aircon systems do would make a lot of sense. I think this is how it works because it take a short amount of time before you start to get hot air coming through. If it was a resistive heater it would be almost instant.
The downside of this would be in winter turning on the aircon would have no effect if it was heating so you loose the added drying effect and windows are more likely to mist up.
Unless they don’t actually run the aircon in reverse but actually redirect the airflow so when heating and you then turn on the aircon as well it takes the air inlet to the heater part from the air which has just left the cooler.

I’m just wondering as the current weather in the uk means the windscreen is very prone to misting when you first get in the car and I was wondering if the normal trick of leaving the aircon on to help demist the windscreen would have any effect when driving in ev mode.

superswiss

What you are describing is called a heat pump and more and more newer EVs have one fitted, because it's more efficient than resistive heating. However, it's a separate unit. They don't run the aircon in reverse. You still have the aircon compressor for cooling and dehumidifying the air. My understanding is that full-hybrids still use the ICE and the residual heat from it when it turns off to heat the cabin, and have electric auxiliary heaters that are switched on when there's not enough residual heat from the engine.

Murton

Thanks. The heating seems as if it is a heat pump rather than resistive heating. Resistive heating would be almost instant but mine takes about a minute to start blowing warm air which is what my household air source heat pumps do.
What you are saying about having the heat pump as a separate unit in addition to the air conditioning does make sense. Technically you could run the aircon in reverse as it’s what domestic aircon units do. You could then switch the inlet air to come from the outlets of the piece getting cold (deliberetly using non technical term) which sounds good in theory but thinking about it more air source heat pumps are prone to freezing and having to go through defrost cycles and placing it in front of the radiator although great when in aircon mode is a terrible place for a heat pump. So yes two independent units seems less efficient but in reality probably avoids significant complexity with routing airflow about so the best solution overall.

superswiss

I would say it depends on how fast the resistive heaters heat up. For efficiency they may not run a huge amount of current through them, so they may heat up somewhat slowly, not like a typical space heater for your house. Also depends on how specifically they are implemented. For example those oil filled electric space heaters also take a moment to heat up the oil in them.

Murton

Yes very true. However the heater works I certainly don’t have any complaints about how quick it warms up the car. My previous w204 petrol was pretty good probably because of the modern exhaust gas recirculation causing the engine to warm up quickly but this car is much quicker.

Diesel Benz

Hybrids do not have a heat pump. The resistive heater (PTC element) heats water in the heater system, it is not heating air like the AUX heaters on diesels. This is why it takes a moment to get warm air. Must be model dependent but the heater elements are about 6 kW, you will notice the battery drain when running the car in electric mode at low outside temperatures.