On Feb 12, 2:08*pm, wrote:
On Feb 12, 1:16*pm, wrote:

Now, who should know more about energy and efficiency? * The DOE or
Bubba?- Hide quoted text -

- Show quoted text -

efficiency and effectiveness are NOT the same thing...

My heat pump is not very EFFECTIVE below 32 becasue it does not keep
my house comforatbale but it is still pretty EFFICIENT. * *Below 32,
the BTU that it puts out drops but so does the electric power that it
pulls.

Below 32, I switch off the heat pump and use oil.

Mark

I would have to disagree that the lower the temperature the less
electricity a heat pump will use. * The efficiency of a heat pump DOES
decline almopst linearly with decreasing temperature. * In other
words, for every KWH of electricity you put in it, you get more heat
out at 45F than you do at 25F. * If it were not so, then you could
just put in larger capacity heat pumps and cost effectively heat homes
where it was regularly 0 degrees, no?

the issue I have is that below 32 the outdoor coils will freeze up and
the thing has to go through a defrost cycle, at that point i say
forget it and switch to oil..

yes due to the defrost cycle the system is less effeicent. I think
the COP at 32 is still probably 2 and above 32 it gets better...

So at 32 it is still cheaper to run then oil and at 45 or so it is
much cheaper to run then oil.

I guess if you count the defrost cycle, then yes it gets a lot less
efficient below 32.


Mark