On 9/16/2012 7:39 AM, wrote:
On Sep 15, 11:40 am, George wrote:
On 9/15/2012 11:16 AM, wrote:





On Sep 15, 10:56 am, "Ralph Mowery"
wrote:
"George" wrote in message

...

He has a Mitsubishi inverter multi zone heat pump (split system). It
doesn't have any resistive elements.

http://www.mitsubishicomfort.com/med...20brochure%203...

According to the graph it has 100% heating capacity down to 5F outside
which tails off to 73% at -13F.

That sure seems like an impressive unit. I did see what appears to be some
resistive heating elements in the individual units that seem to be an
option.

I think this is just another sales job and you're on to the
truth. It only shows that it has 100% CAPACITY down
to 10F, not how it gets that capacity. Unless the laws of
thermodynamics have been repealed, the efficiency of
ALL heat pumps declines as the outside temp drops.
It's a matter of physics that no manufacturer can avoid.
They can still deliver more heat than a resistive heating
element would at 10F, but the amount of heat you get
out of the heat pump drops on a steady curve as the
temp goes down.

The only way they can get 100% capacity across that
broad temp range is either by:

A - using resistive heat to supplement

B - Downrating the whole thing so that it's rated by what
it produces at 10F.

Option B is nuts for obvious reasons.

I think you would want to contact Mitsubishi and explain to them that
the systems they sell can't work as described (hint, Mitsubishi makes
really well engineered stuff and they tend to be really anal about
describing actual performance)

Then you contact my friend and let them know the performance he actually
witnessed isn't possible in his system since it doesn't have resistive
elements.

And maybe you just don't see that everyone who posts in this group isn't
heybub just telling stories to screw with people...- Hide quoted text -

- Show quoted text -


I looked at the brochure in more detail. It appears that they
do not use resistive heating elements. Now I suggest you
look at the actual spec data in the brochure. Look at
page 12, about 1/4 of the way down. It states that the
rated capacity for the first model is 10,900BTU at 47F and
6,600BTU at 17F. For the largest model, it's rated at
18,000BTU at 47F and 11,300 at 17F. And then maybe you
can explain how that jives with the performance curve
in the graph that shows 100% capacity down to 10F.
It is however consistent with physics and what we know
about heat pumps, regardless of who builds them.


Isn't that a little different than it can't work and it must have
resistive elements?