Most efficientbsetting for heat pump?

[taraquin]

After some conflicting info on heat pump efficiency/longevity I ask the experts here:
Claim 1: Running the heat pump at low fan setting (comfort aside) is more efficient as less air needs to be heated cooled. Some observations in servicemode where lower fanspeed equals lower compressor rpm.
Claim 2: Running the heat pump at medium/high fanspeed is better for longevity if heat pump and more efficient as gas temp/pressure is lower in compressor as more air passes through, especially at very low or very high temperatures.

In my TM3 with ptc lower fanspeed draws less power when I measure from wall at steady state temp.

I lean towards claim 1, but I honestly dont understand compressors at more than a basic level. What do the experts say?

 

[ngng]

After some conflicting info on heat pump efficiency/longevity I ask the experts here:
Claim 1: Running the heat pump at low fan setting (comfort aside) is more efficient as less air needs to be heated cooled. Some observations in servicemode where lower fanspeed equals lower compressor rpm.
Claim 2: Running the heat pump at medium/high fanspeed is better for longevity if heat pump and more efficient as gas temp/pressure is lower in compressor as more air passes through, especially at very low or very high temperatures.

In my TM3 with ptc lower fanspeed draws less power when I measure from wall at steady state temp.

I lean towards claim 1, but I honestly dont understand compressors at more than a basic level. What do the experts say?

Are you more interested in preserving hardware, comfort, or efficiency?

 

[taraquin]

Are you more interested in preserving hardware, comfort, or efficiency?

Preserving hardware and efficiency

 

[ngng]

Preserving hardware and efficiency

You should be able to get a rough estimate of efficiency by choosing various settings and viewing the after-trip report. I can't speak to preserving hardware though.

 

[Iron]

Are you driving long distances where range is a concern, or just trying to eek out every penny of efficiency you can? I charge to 60% and set it to whatever the heck I feel like for my daily commute. It's plugged in nightly so no range issues.

 

[taraquin]

The geekninside wants to know. I dont have a Y with heat pump now.

 

[Big Earl]

For ultimate longevity and efficiency, turn it off.

 

[mborkow]

For ultimate longevity and efficiency, turn it off.

I thought it was good to let the AC run and that letting it sit idle for long stretches might cause problems…

 

[taraquin]

For ultimate longevity and efficiency, turn it off.

Ofcourse, but I was curious which of the claims were correct

 

[Johnny Vector]

Ofcourse, but I was curious which of the claims were correct

It almost certainly depends on outdoor temperature and humidity, cabin temperature setting, and probably some other factors. Also, I would be very surprised if you can make any significant difference in efficiency by changing the fan speed. Like, with very careful measurements over the course of months you might be able to tease out a signal that you could believe, but any measurements you personally can do are going to be swamped by other variables.

 

[Iron]

When I first got the Y, I was running the AC at what I thought was an efficient setting. My wife (ICE BMW driver who is not gentle on cars) looked at me and said something like.... "what the eff is going on with this AC? I heard electric cars don't have good AC...." Next drive, I froze her ass off till she complained about how cold it was. Since then, I run the heat and AC like I would in an ICE car. Point is, this is just a car first and foremost. If we have to baby the HVAC/creature comforts and worry about efficiency, I could see a lot of ICE drivers not wanting to bother with EVs. (Not directed at OP, just my general opinion).

 

[cmaster]

Preserving hardware and efficiency

Probably anywhere between 73-77 degrees F for colder areas. And, around 65-69 during the summer.

 

[fiehlsport]

When I first got the Y, I was running the AC at what I thought was an efficient setting. My wife (ICE BMW driver who is not gentle on cars) looked at me and said something like.... "what the eff is going on with this AC? I heard electric cars don't have good AC...." Next drive, I froze her ass off till she complained about how cold it was. Since then, I run the heat and AC like I would in an ICE car. Point is, this is just a car first and foremost. If we have to baby the HVAC/creature comforts and worry about efficiency, I could see a lot of ICE drivers not wanting to bother with EVs. (Not directed at OP, just my general opinion).

Yeah, I agree, I haven't changed my HVAC tactics with this car at all. Just run the climate on Auto 100% of the time and let it do its thing. When the car reaches the "setpoint" the heat pump will idle as low as possible to maintain the cabin temp. This is the best for longevity. No messing with fan speeds, vent positions... just Auto + 69F or whatever reasonable temp you desire.

Boggles my mind when I see Teslas with the climate on LO or HI with the heatpump screaming under the frunk...

 

[cmaster]

Rich Rebuild earlier videos was that at the super chargers, to improve charging speed, set your heat to maximum. Well, from experience, it's a very bad idea. lol....This will wear down some components faster than others leading to premature failure. Some of his videos, you need to take a step back and think about it for a second.

 

[taraquin]

Yeah, I agree, I haven't changed my HVAC tactics with this car at all. Just run the climate on Auto 100% of the time and let it do its thing. When the car reaches the "setpoint" the heat pump will idle as low as possible to maintain the cabin temp. This is the best for longevity. No messing with fan speeds, vent positions... just Auto + 69F or whatever reasonable temp you desire.

Boggles my mind when I see Teslas with the climate on LO or HI with the heatpump screaming under the frunk...

My initial qeurstion was how running fanspeed on lo, med or high affects efficiency and longevity of components

 

[Foxsbiscuits]

I found this article quite interesting -

Blower Motor Guide in 2020 - A Complete Guide to Car Blower Motor

Many people do not know AC blower motor function or even where to find it in a vehicle. Here is a complete guide to automotive blower motor.

sontianmotor.com

My conclusion is that speed doesn't matter so much, seems more likely to fail for other reasons.
In terms of efficiency... I would guess negligible difference, unless a higher fan speed also matched with the HVAC heating/cooling more which would use more energy.
On Auto mine runs at a low speed most of the time, it's quiet and keeps a consistent temp. Continual running at low speed is a good thing for heating/cooling systems in my mind as opposed to on/off blasting repeatedly. "In Auto we trust"

When I first got this car I was concerned with constant moving of parts, mirror housing and mirrors, seats, steering wheel, fan positions. In my mind those are tiny fragile gearings that are likely to break so I tried to minimise those movements as much as possible but it's another thing about the car I had to learn to accept as ok to use, have to change my mind about it. So now I have easy entry bringing the steering wheel up as high as possible for my long legs and I don't worry about it "overusing" the motors.

 

[MY-Y]

Here is some data to further the conversation. I did a quick test with Scanmytesla this morning.

Quick summary: Medium Fan speed is best. Probably should just use "auto."

Theory: Air is made hotter at low fan speeds to meet temp setpoint, so setting the fan too low is inefficient.

I tested many fan speeds at a constant temp, recirc on and off, and the results are consistent and surprising. Outdoors 40* car temp setting 73*. The car with the HVAV off draws 350 watts from the battery, so that would need to be subtracted off for a true HVAC draw.

Fan speed: watts
1: 1700
2: 1200
3: 950
4: 850
5: 830
6: 800
7: 900
8: 1000
9: 1100
10: 1200

Then I held the Fan speed for several minutes, no recirc, to make sure I was near steady-state.
6: 950
4: 950
1: 1400

Note: the scanmytesla app fluctuates, so the power draw numbers aren't precise. They are my eyeball estimate of the jumpy numbers. The trends are there for sure though.

One thing is clear: Manually forcing the Fan to 1 is less efficient.

 

[fiehlsport]

My initial qeurstion was how running fanspeed on lo, med or high affects efficiency and longevity of components

Is the situation you're considering already using Auto mode, just to be clear? (Since we now have the Low, medium, high fan speed override when using Auto)

 

[taraquin]

Is the situation you're considering already using Auto mode, just to be clear? (Since we now have the Low, medium, high fan speed override when using Auto)

Yes auto. I aint got heat pump in my model 3, this is just out of curiosity

 

[Foxsbiscuits]

And just for clarity - Auto low/med/high fan sets the maximum that auto will run. So when I have it Auto High it can still run low, as it does for most of it.