Heat pump vs non heat pump. What is the difference in efficiency

[Phil_Gtown]

As far as a heat pump, it really depends on what you define as 'cold' for your area. Depending on the heat pump you won't get much (any?) benefit below 15F (-9C). Some heat pumps lose most of the efficiency benefit by 20F to 32F (-7C to 0C). As the temperature drops the heat pump will be putting out warm air, not hot air, and may need to supplement with resistive heating (which means more energy usage than all heat pump). So, at 0F (-18C) the heat pump will be no benefit; at 45F (7C) it will be much better than resistive heating. As it gets colder the heat pump loses efficiency AND the battery loses capacity; the loss of range due to low temperatures will be less at milder temperatures but may fall off more suddenly at a certain low temperature.

There are advanced heat pumps that work in colder temperatures. I'm not sure if they are available in vehicles. These cold climate heat pumps are made by Mitsubishi and maybe others.

Good info, I wonder what’s the effectiveness of the heat pumps in Model Y ?
If the typical models are a lot less effective under -7 Celsius then I’m ok with that since for us most of 3 months is colder than that (in NCR)

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[Zardoz]

Don’t know what kind of heat pumps you have in America, but in Norway - a land that is cold, 80% of houses has heat pumps. Many of them are rated to work down to -30C (celcius, 0 is when water freeze), even though they get less effective when you get down to the double digits minus temperature.

my latest heat pump gives roughly 6 to 7 times the amount of heat for the same amount of electricity a heat element would give down to around 0C. Then it goes down to “only 3-4) until close to double digits, before it eventually is a 1-1 at minus 25.

Whether heat pumps or not, look at Tesla (not their leader), and look how much range it loses compared to ideal vs worst conditions, then do same for our car. Heck, on a -12 trip last year I could not get warm and around half the energy was used for heating. That is not great.

I haven't been in the market for a heat pump for about 10 years. When I was looking at them the cold weather options were limited in the States. Canada had a Mitsubishi cold climate option, but it wasn't sold where I'm at Installers here are hesitant to try anything new.

With that said, the numbers you've given are great. We need to have that level of heat pump tech in some parts of the States.

 

[Murse-In-Airy]

That is impressive. I think I am getting an idea what you are saying. Each has its advantages. I believe that a long trip in a temperature that is not artic would favour the heat pump. Short trips seem to favour the resistive heater set up, which makes a lot of sense.since instant heat is the byproduct. Short trips in turn mean charging at home is cheaper.
Thanks a bunch!

That seems to be a pretty good summary. Midwest/western US cold would be served pretty well by a heat pump. Northeastern/ Canadian cold maybe not so much.

 

[awp0]

Good info, I wonder what’s the effectiveness of the heat pumps in Model Y ?
If the typical models are a lot less effective under -7 Celsius then I’m ok with that since for us most of 3 months is colder than that (in NCR)

This old range test suggests that the Model Y's heat pump is, at best, only effective somewhere above 16F because the MME and MY have almost identical tested ranges at 16, 50 and 80 degrees.

https://www.macheforum.com/site/threads/cr-report-on-ev-range-tests.20961/post-494312

 

[ChasingCoral]

Second question to this, has anyone heard any rumours that the 2025 will be getting the heat pump like the F150 did for 2024?

No need for rumors. The heat pump is on the 2025s.
https://www.macheforum.com/site/thr...hanges-heat-pump-ventilated-seats-more.39560/

 

[byoungblood]

As far as a heat pump, it really depends on what you define as 'cold' for your area. Depending on the heat pump you won't get much (any?) benefit below 15F (-9C). Some heat pumps lose most of the efficiency benefit by 20F to 32F (-7C to 0C). As the temperature drops the heat pump will be putting out warm air, not hot air, and may need to supplement with resistive heating (which means more energy usage than all heat pump). So, at 0F (-18C) the heat pump will be no benefit; at 45F (7C) it will be much better than resistive heating. As it gets colder the heat pump loses efficiency AND the battery loses capacity; the loss of range due to low temperatures will be less at milder temperatures but may fall off more suddenly at a certain low temperature.

There are advanced heat pumps that work in colder temperatures. I'm not sure if they are available in vehicles. These cold climate heat pumps are made by Mitsubishi and maybe others.

Bosch makes a residential unit as well, I have it at home.

I live in NW Virginia, and mid to high 20s are probably as cold as it gets over a span of a few days in a row. This past winter was the first where the new system ran all winter long. It only called for resistance heating because I have my thermostat configured to allow it if the heat pump is taking too long to warm the house back up after being on a lower setting. But if the house was already at set temperature, it would run on the heat pump alone down into the mid teens F. Per the manual it is supposed to be able to run down to 0F.

I think the heat pump in EVs would be most beneficial to those in cooler, but not cold climates, where you see a drop in range due to the car having to run the heat to maintain battery temperature, and when you just need a little bit of heat to break the chill in the cabin. I can be OK on the heated seats and steering wheel alone down to the high 40s F, below that, I usually need a little heat going to stay comfortable.

 

[Jimrpa]

No need for rumors. The heat pump is on the 2025s.
https://www.macheforum.com/site/thr...hanges-heat-pump-ventilated-seats-more.39560/

I just hope they have additional electric resistance heaters for those times the temps drop below 35-40 (Fahrenheit; about 2-5 centigrade for those who use those units).

 

[Fixbear]

I live in the cold. Just south of Ontario in NY on the south bank of the St Lawrence. I have heat pumps / minisplits for my house. When it’s cold out, 15°F and under, my heat pumps, which are specially certified for the cold I live in, quit working. They spend more electricity cycling a defrost mode, during which the house is getting colder and colder, than they do warming up the house. So I have to kick the propane forced air furnace on.
So take my heat pumps, and add the cooling effect of airflow from driving… nah, I’m good. I’ll keep my resistive heater. Sure it costs range. A heat pump might be more efficient above 32°F, but once it’s below freezing, it’s going to work less and less until it just can’t keep up. At some point it will be using just as much range, only without producing any actual heat.

I’ll keep my resistive electric heat.

That problem with your house system is in the designers error. They under-specked it to give you a lower price. The downwind side of the St Lawrence has a lot of moisture in the air and makes a lot of Rhine ice. So for sure your backup heat will have to come on. Also be aware that different brands use different systems to de-ice the coils. They are not a every where unit. And one should always check with reliable sources in their specific area for what is good and works and what doesn't.

 

[medriver]

This is a far more complicated calculus than we are likely to understand.

For simplicity sake a resistive heater creates heat at a 1:1 ratio, a heat pump CAN OPERATE UP TO 1:3 (or more, but probably not in a car) meaning they can transfer 3 watts of heat for 1 watt of input.

But this is far from simple as a heat pump has a duty cycle, what your car actually needs i.e. the battery, cabin, outdoor temperature, blah blah blah.

In the end why nobody REALLY cares is this only really matters in max range cases in colder weather where charging is hard to come by, otherwise does it REALLY matter?

However the car SHOULD BE more efficient with a heat pump, so hard to say why not have one (and we've just told it does) in the future.

 

[zvez]

Just an FYI to OP, ford announced details of 2025 mache and one of the changes is addition of a heat pump. There's a thread on the forum all about the 2025 posted today

 

[ChasingCoral]

I just hope they have additional electric resistance heaters for those times the temps drop below 35-40 (Fahrenheit; about 2-5 centigrade for those who use those units).

I thihe existing heater is still in there.

This is a far more complicated calculus than we are likely to understand.

For simplicity sake a resistive heater creates heat at a 1:1 ratio, a heat pump CAN OPERATE UP TO 1:3 (or more, but probably not in a car) meaning they can transfer 3 watts of heat for 1 watt of input.

But this is far from simple as a heat pump has a duty cycle, what your car actually needs i.e. the battery, cabin, outdoor temperature, blah blah blah.

In the end why nobody REALLY cares is this only really matters in max range cases in colder weather where charging is hard to come by, otherwise does it REALLY matter?

However the car SHOULD BE more efficient with a heat pump, so hard to say why not have one (and we've just told it does) in the future.

"Heat pumps help preserve range in cold weather and add about 20 extra miles, says Donna Dickson, Mustang Mach-E chief engineer."
https://www.pcmag.com/opinions/fords-stylish-2025-mustang-mach-e-is-still-catching-up-with-the-herd

 

[Exordium01]

You are assuming the heat pump only has access to outside air. GM and Tesla connect the heat pump to motor waste heat, which makes it even more efficient. They only need resistive heating at the beginning of the drive, prior to the motors warming up.

Waste heat is already going into the cabin on the current MME. You can’t get any more efficient than directly using waste heat.

Resistive electric heaters are the most responsive. My Subaru had resistive heaters in order to provide instant heat and would switch over once the engine heated up.

the problem with the MME is the electric is used to heat everything and isn’t powerful enough to heat both cabin and battery in extreme cold. Unfortunately, heat pumps lose efficiency in extreme cold. The 2024s have a more powerful electric heater which will help and the heat pumps will increase efficiency by a bit in moderate cold.

 

[Fremont Kid]

Don’t know what kind of heat pumps you have in America, but in Norway - a land that is cold, 80% of houses has heat pumps. Many of them are rated to work down to -30C (celcius, 0 is when water freeze), even though they get less effective when you get down to the double digits minus temperature.

my latest heat pump gives roughly 6 to 7 times the amount of heat for the same amount of electricity a heat element would give down to around 0C. Then it goes down to “only 3-4) until close to double digits, before it eventually is a 1-1 at minus 25.

Whether heat pumps or not, look at Tesla (not their leader), and look how much range it loses compared to ideal vs worst conditions, then do same for our car. Heck, on a -12 trip last year I could not get warm and around half the energy was used for heating. That is not great.

Your home heat pumps are probably geothermal rather than air exchange. Efficient even during the winter. Vehicles will need to be air exchange or might gather heat from the motors, as stated previously.

 

[Mache_Nor]

You are correct that there are air to air, geothermal to air / water as well as water to air / water pumps, it really is a complicated matter if one delves into it. My home has air to air pump. Double checked now, seems it was not 7 but 5.1 factor; e.g. 1 kw energy in = 5.1 kw heat out under ideal conditions. It has 2.7 at -25 C. Norwegian page but should be easy to translate with the browser: https://ludvigsen-varme.no/product/toshiba-signatur-35/.

Long story short, yes, car vs house makes it even more complicated to evaluate the need, but as even Ford now has stated that heat pump leads to 20 miles more range, this is done, it’s just a better (not perfect) technology for EVs.

 

[ChasingCoral]

You are correct that there are air to air, geothermal to air / water as well as water to air / water pumps, it really is a complicated matter if one delves into it.

It's hard to implement geothermal heat pumps in cars. It really reduces the range.

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