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Is heating of the cabin (excluding the heated seats) purely resistive/battery powered, or is heat also extracted from coolant as well (as it is in an ICEmobile)?
As far as I know, the seat heaters are purely resistive.
As for cabin heating, the Model S does use waste heat from the motor and inverter, but the EV propulsion system is pretty efficient, and below about 50˚F, 10˚C, there is not enough waste heat to keep the cabin warm. After that, the car uses purely resistive heating for cabin heat. Although the air conditioner could be turned around into a heat pump at better efficiency down to -10˚C or so, Tesla has chosen to keep the systems simple, and only use resistive cabin heating.
Some diesel cars do this too. My 335d begins heating immediately with an electric heating element because Diesel engines take much longer to warm up than gasoline engines. Otherwise my entire commute would be freezing cold in the winter.Unlike an ICE car, where the engine/coolant has to be warm before the cabin gets any heat, Model S's resistive heater begins heating the cabin at full strength as soon as you turn it on. In practice, you can just get in the car and drive: the interior gets comfortable quickly; for ultimate comfort you can turn on the climate control ahead of time. If you are plugged in, however, it's always best to turn on climate control and heat the cabin before you unplug and drive, because all that energy comes from the wall instead of the main traction pack: your Wh/mi will be significantly lower, especially for shorter trips.
My previous house in the Phila area had heat pumps and it got down below 32 often in winter. There is still energy that can be extracted from air below 32 F, just less of it, so it is less efficient. There was a resistive element for backup and I usually switched flipped the switch on the thermostat to backup when it got below 35 F. An HVAC guy I knew told me it was more efficient and cost-effective to do so.I thought heat pumps couldn't operate below ~32 F (0 C) because it would create ice?
Unless you have a 200+ mile trip before plugging back in, and are concerned about cutting it close, what's the difference? You are going using that energy one way or another - either up front from being plugged in or on the back end when recharging.If you are plugged in, however, it's always best to turn on climate control and heat the cabin before you unplug and drive, because all that energy comes from the wall instead of the main traction pack: your Wh/mi will be significantly lower, especially for shorter trips.
Unless you have a 200+ mile trip before plugging back in, and are concerned about cutting it close, what's the difference? You are going using that energy one way or another - either up front from being plugged in or on the back end when recharging.
Ok - that HVAC guy is flat out wrong. He cost you a lot of electricity.
A decent modern heat pump can beat resistant heat to below zero. At 32 degrees, a typical COP is 3.0 which is the terminology used to mean 3 times more efficient than resistant heat.
Now a really old heat pump - perhaps a COP of 2.0 at 32 degrees. Now the compressor of course will wear out faster the lower temps you run it down to. Cost effective taking compressor life into consideration is a fairly variable situation. But "efficient" - no brainer
I thought heat pumps couldn't operate below ~32 F (0 C) because it would create ice?
Most HVAC guys have no clue. How would they? They never track energy use. Imagine a car mechanic who never tracks even his own mpg telling you how to save gas...My previous house in the Phila area had heat pumps and it got down below 32 often in winter. There is still energy that can be extracted from air below 32 F, just less of it, so it is less efficient. There was a resistive element for backup and I usually switched flipped the switch on the thermostat to backup when it got below 35 F. An HVAC guy I knew told me it was more efficient and cost-effective to do so.
Ok - that HVAC guy is flat out wrong. He cost you a lot of electricity.
A decent modern heat pump can beat resistant heat to below zero. At 32 degrees, a typical COP is 3.0 which is the terminology used to mean 3 times more efficient than resistant heat.
Now a really old heat pump - perhaps a COP of 2.0 at 32 degrees. Now the compressor of course will wear out faster the lower temps you run it down to. Cost effective taking compressor life into consideration is a fairly variable situation. But "efficient" - no brainer
Interesting. In my case, my knowledge is comparing heat pumps to natural gas heat on my hybrid system for my house. Below 40F the system switches to gas. It's configurable, but the limit is 32F. My understanding is at that point I would be using gas to defrost the condensers which defeats the purpose.
So how long does it take to warm up the car? Say its in the 20's and you have a 15 min ride, will it be cold the entire ride or will it warm up after a short time? Also how long does it take to warm the car with the smartphone app? I can picture us in a restaurant and programing the car to warm up before we are finished dinner. How much time should I allow for that to happen?
I thought heat pumps couldn't operate below ~32 F (0 C) because it would create ice?
Really? I always thought natural gas furnaces were a lot cheaper than heat pumps to operate when you compared the natural gas cost and electricity cost.
and the gas fired furnace may get ~90% of the gas converted into heat in the house
Modern heat pumps work efficiently to -20f.
Most HVAC guys have no clue. How would they? They never track energy use. Imagine a car mechanic who never tracks even his own mpg telling you how to save gas...
Because you can install a box in a basement doesn't magically make you expert on energy efficiency.
+1
There are a WHOLE LOT of "it depends" in that. If you have a Carrier Infinity you can enter your fuel rates and it can figure it out for you, chances are it'll be colder than 30.
For smaller homes we recommend abandoning the gas meter altogether. Commiting to gas infrastructure is chasing hypothetical pennies with real dollars. The meter/billing fee handicap can not be recovered by "cheaper btu". And that "cheaper" is not likely to persist as gas consumption ramps, and solar prices continue to drop.
House size, equipment/enclosure load match matters, and enclosure deficiencies.
It is a carrier infinity system. I've not seen a way to enter fuel costs either in the advanced menu or the service hidden menus. I'm also on a TOU plan so the calculation is likely beyond the thermostat's ability.
I have an infinity system with the infinity touch thermostats. I can enter fuel costs for electric and propane to display usage cost. But I am told it doesn't use those numbers in determining switchover from heat pump to propane.
My older infinity thermostats do not have a place to enter energy cost.