On Thu, 14 Nov 2019 16:48:08 -0500, Frank Krygowski
wrote:

On 11/14/2019 2:14 PM, David Scheidt wrote:
AMuzi wrote:
:On 11/14/2019 11:38 AM, David Scheidt wrote:
: Frank Krygowski wrote:
: :On 11/13/2019 9:21 PM, Ralph Barone wrote:
: : jbeattie wrote:
: :
: :
: : Don't you guys have NG?
: : https://energykinetics.com/savingshe...elcomparisons/ NG beats every
: : other fuel in terms of cost per therm and low levels of pollutants.
: :
: : -- Jay Beattie.
: :
: :
: : In the Pacific Northwest, electrically powered heat pumps rate better than
: : in New England, due to cheaper electricity rates, higher SEER due to higher
: : ambient temperatures, and zero emissions from hydroelectric dams.
:
: :That seems to make sense. I was surprised to read, several years ago,
: :that Ontario was heavily promoting heat pumps. They're not very
: :efficient at low air temperatures.
:
: There are lots of units that have an efficency of greater than 100%
: down to -14F.
:
: :https://www.cbc.ca/news/canada/new-b...neer-1.4024786
:
: I'd have to see his numbers, but I expect he's under calculating the
: efficency of the heat pump.
:

:??
oes 'efficency of greater than 100%' mean you get more
:energy out than you put in?

Yes. That's how heat pumps work. They pump heat from where you don't
want it to where you do, which is more effecicent that making the heat.
In the case of an air source heat pump used for heat, that's the outside
to the inside. used for cooling, it's the other way around.

Instead of describing it as efficiency greater than 100%, it's normally
called the Coefficient of Performance. See
https://en.wikipedia.org/wiki/Coeffi...of_performance But for heat
pumps COP is highly dependent on outside temperature. The colder it gets
outside, the worse the COP. It's analogous to pumping water up a higher
distance. It takes more work.

Heat pumps can be a good deal, especially where winters are mild and
summers are hot enough to need AC. You're paying for AC hardware
(compressor, a couple of heat exchangers, etc.) to pump heat out in
summer, so why not add a few valves to pump heat in during the winter?

I remain surprised it makes sense in a chillier place like Ontario,
where AC is much less a necessity. Seems payback period on that hardware
would be a lot longer, especially compared to inexpensive natural gas.
Not to mention tactics like super-insulation.

IIRC Carl Fogel had a heat pump and was pretty dissatisfied with it. I
don't remember why, though.

I wonder about the effectiveness of a heat pump in, oh say, Bangor,
Maine, where the temperature got so low some nights that kerosene
wouldn't flow in a pipe from the outside tank to the space heater?
--
cheers,

John B.