Vapor injection heat pump

[husky10101]

New construction with spray foam insulation. Can't get much better than that.

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[Ventorum94]

Home heat pumps can cool and heat but not efficient in the cold so the home also has a normal furnace as a backup. Assume vehicle HP's are the same.

Not the same. The new “vapor injection” heat pumps (as on ‘24 Lightning, not used on most home units) perform better at very cold temps than conventional heat pumps. Google “vapor injection heat pump.”

 

[Tony Burgh]

Not the same. The new “vapor injection” heat pumps (as on ‘24 Lightning, not used on most home units) perform better at very cold temps than conventional heat pumps. Google “vapor injection heat pump.”

But there is no “free lunch”. Just optimized to reduce equipment size. We did similar liquid injection 30 years ago in chemical plants. With 15,000 bhp motor driven screw compressors. It works. The question always was how to simplify and keep capital costs down.

 

[BennyTheBeaver]

Just a thought:

Ford added heated seats to the Pro just to claim 10 extra miles (4.2%) on all SR trims in 2023. If the heat pump makes a difference of 4.2% or more, wouldn't they adjust their range estimates? They were desperate enough to add heated seats to a trim.

 

[tls]

It makes sense that it would.

That’s going to be a pretty big unit. It’ll need to be 4x the capacity of just an air conditioner.

Why would that be? I don't know how to calculate heat loss for a moving vehicle, but for residential applications, cold-climate or "hyper heat" vapor injection heat pumps have about 1.3X the max (not "rated") heating vs cooling output compared to cooling-only models. In my climate, with a cooling design day around 90F, you're right that's still more cooling than is needed, but it's not 4X as much, and there are a lot of places in North America where it's much hotter than here.

 

[husky10101]

Not the same. The new “vapor injection” heat pumps (as on ‘24 Lightning, not used on most home units) perform better at very cold temps than conventional heat pumps. Google “vapor injection heat pump.”

Thanks will have to look into Vapor HP. First I heard of these

 

[TomB985]

I’ve driven four EVs through Minnesota winters. Two had heat pumps(Model Y, EV6) and two did not (Model 3, F150 Lightning). There’s a noticeable difference with a heat pump, and the system in my Model Y was effective as low as -10º F to keep me warm. That car didn’t have a supplemental PTC heater, but the compressor was able to throw out enough heat to effectively keep me warm in subzero temps.

I sold my Model Y last November, so my most recent experience with a heat pump is my mom’s new EV9. That three-row CUV has a larger cabin than my Lightning, and it draws at least 50% less than my Lightning would to maintain a comfortable cabin. In 20º weather, it would use about 2.5-3.5 kW, and my Lightning will draw 5-7 kW to the coolant heater.

I agree that cold, dense air makes a big difference, but the real world range difference with a heat pump can be substantial on a trip. My Lightning has a big enough battery to get me home on my longest commutes in January, but I struggle to hit 1.3 mi/kWh when it gets cold out.

If I were buying today in Minnesota, I’d spend a bit more to get the ‘24. That may be different if I lived further south where cold weather wasn’t as much of a concern.

 

[tls]

A few months after trading in our 2015 Model S (no heat pump) for a 2020 Model Y (heat pump, no PTC) we took it to Massif de Charlevoix in Quebec in December. There was no lack of cabin heat, in temperatures as low as -30F overnight and routinely dipping to around -20F while driving. It was actually much more comfortable than the trip we took in the Model S a few years earlier.

While it's true the newer Teslas don't have a "PTC"/resistive heating coils, they are able to produce a very large amount of heat using the motors themselves, even without the wheels turning. The motor controllers deliberately go into an "inefficient" mode that produces less torque and more waste heat. That heat is then recovered by the heat pump and returned to the cabin (or if necessary the battery). I don't know if Tesla has patented this but it seems like a much better system than what other EV manufacturers use.

 

[Jake24]

If I were buying today in Minnesota, I’d spend a bit more to get the ‘24.

worth it

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