I had to look this up on Wikipedia since a 100% efficient resistive heater is 
hard to beat, but I guess I didn't understand that the heat pump is getting 
added energy from the environment.  "
Heat energy naturally transfers from warmer places to colder spaces. However, a 
heat pump can reverse this process, by absorbing heat from a cold space and 
releasing it to a warmer one. Heat is not conserved in this process and 
requires some amount of external energy, such as electricity. In heating, 
ventilation and air conditioning (HVAC) systems, the term heat pump usually 
refers to vapor-compression refrigeration devices optimized for high efficiency 
in both directions of thermal energy transfer. These heat pumps can be 
reversible, and work in either direction to provide heating or cooling to the 
internal space.Heat pumps are used to transfer heat because less high-grade 
energy is required than is released as heat. Most of the energy for heating 
comes from the external environment, only a fraction of which comes from 
electricity (or some other high-grade energy source required to run a 
compressor). In electrically-powered heat pumps, the heat transferred can be 
three or four times larger than the electrical power consumed, giving the 
system a coefficient of performance (COP) of 3 or 4, as opposed to a COP of 1 
for a conventional electrical resistance heater, in which all heat is produced 
from input electrical energy.Heat pumps use a refrigerant as an intermediate 
fluid to absorb heat where it vaporizes, in the evaporator, and then to release 
heat where the refrigerant condenses, in the condenser. The refrigerant flows 
through insulated pipes between the evaporator and the condenser, allowing for 
efficient thermal energy transfer at relatively long distances.[5] "
 

    On Tuesday, November 28, 2017 8:42 PM, Bill Dube via EV <ev@lists.evdl.org> 
wrote:
 

 If you what to get quite fancy, modern OEMs use a heat pump run with a 
small variable frequency drive. About 4x the efficiency of a resistive 
heater. No joke, and that is a serious increase in range in the winter. 
No doubt, you can get a Leaf compressor cheap in the bone yard.

By adding the proper valving, you have the bonus of air conditioning, 
but that is even more of a project. The good thing is, you can reuse the 
cars existing air conditioning condensor and evaporator and some of the 
A/C plumbing.

It can get quite complicated, however, and a resistive ceramic type 
heater core is, no doubt, the simplest option. I'd opt for a "high/low" 
switch (series-parallel?) on two ceramic heaters, or some sort of 
thermostat on the outgoing air from the heater(s).

Bill D.

On 11/28/2017 4:33 PM, Bob Bath via EV wrote:
> Respectfully, when I did Civicwithacord, the goal was defrosting the 
> windshield effectively, not keeping me warm. Yanking out the dash to install 
> the ceramic heater in the old fluid core housing was easily the biggest b---h 
> of the conversion, but the time and look and safety was well worth it!!
>
> Bob Bath, from his iPod, so any misspellings are from autocorrect or fat 
> fingers on a small device, not cluelessness...
>
>> On Nov 28, 2017, at 3:13 PM, Bill Dennis via EV <ev@lists.evdl.org> wrote:
>>
>> I used a 1500W heater core in my Geo Metro conversion, and I'd say that it
>> kept the car kinda "warmish" on really cold days.  But I think if I'd taken
>> the time to put extra insulation in the car, that would have helped.
>>
>> Bill
>>
>>

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