In the Leaf, the heat pump will reduce the heating loads from ~5kW to
less than 1kW. Big difference in range in the winter.
Heat pumps typically deliver about a factor of 3 (or better, theoretical
maximum of about 8,) reduction in energy consumption over a resistive
heater. That is why it is worth installing the complicated system.
Yes, a heat pump will typically use 1/3 the energy to supply the same
heat. (A resistive heater has a Coefficient of Efficiency of 1.0 ).
Seems too good to be true, but trust me, they deliver. I even have a
heat pump to heat my garage in the winter. It will pay for itself in
about a season, maybe two. I installed it myself, which reduces the
initial cost by about a factor of two.
Here is link about the Coefficient of Efficiency (COP) of a heat pump
systems:
https://en.wikipedia.org/wiki/Coefficient_of_performance
Often, heat pumps will have a SEER rating, which can be converted to a COP:
https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_ratio
In a nutshell, you are "pumping" the heat "uphill" from the cooler air
outside and forcing it into the warmer air inside.
Bill D.
On 12/24/2015 12:57 PM, Ing. Marco Antonio Gaxiola via EV wrote:
How can you measure the difference in efficieny by using a
'resistive' heater Vs a compressed gas system? (AC turned backwards)
We have an air conditioned at our home that usually works for cool
air since we have extreme very hot summer here (Hermosillo Sonora Mexico)
but this unit has a heater option that actually uses a 2 pole-bidirectional
electro-valvle to reverse operation. So it works great! And we do not have
much trouble of having the 'evaporator' (the one outside when in heater
operation) getting freezing since our wheather is usually dry most of the
time during winter.
But my concern is, all the work (power) the motor for the compressor
and the two more for fans of the condenser and evaporator, would consume
more energy Vs the heat efficiency of simply using a resitive heater?
Robert, ohh yes... those small-cheap inverters are so efficient and
powerful that can run big loads compared to the old conventional 10:1 or 5:1
transformer ones. I ran all house lights, electronic appliances such TV and
internet stuff and our 7.4cu ft. refrigerator on a small inverter powered by
a used lithium cells for about 2hrs during a big black out some months ago.
Marco Gaxiola
www.energyev.com
-----Mensaje original-----
De: EV [mailto:ev-boun...@lists.evdl.org] En nombre de Robert Bruninga via
EV
Enviado el: jueves, 24 de diciembre de 2015 11:55 a.m.
Para: Electric Vehicle Discussion List
Asunto: [EVDL] EV Heatpump Retrofits
All it takes to install a heatpump in an EV is to find a place for a cheap
$89 window airconditioner turned backwards.
I use Window AC units for heat in my kitchen, bathroom, and at times past in
the hallway.
I was astounded when I tried running one on a cheap $99 12v/120v modified
sinewave inverter and it started right up. It ran with a load of about 650
watts.
Now all you have to do is figure out where to put it in the EV. And that is
not as much of a challenge as you might think, depending on your aesthetics.
of course when you need it most, and the coldest eemperatures it wont be
worth much and will freeze up.
Bob, WB4aPR
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