[Strawbale] Low-Cost Solar Assisted Heat Pump System littlehouses cross post

[Shody Ryon]

Re:Low-Cost Solar Assisted Heat Pump System

From: "John" <patjohn51 at ...>

> I have been thinking along the same lines as you
about a
> portable a/c like the Amcor Nanomax A12000E. I
thought,
> why not remove the burner from an old gas water
heater,
> then run the warm air discharge into the bottom. The
water
> heater has a flu where the gases rise as the water
is heated.
> The warm air from the Amcor would follow the same
path.

Hi John;

The internal flue works great for the high temperature
gases
of a propane or natural gas heater, but is not
adequate for the
low temperature air from the little air conditioner.
However,
there is several times that much surface area, to use
in addition
to the internal flue, on the outside of the tank,
including the top
and bottom surfaces. So, the tank gets placed inside
of an
insulated box, with enough space around it for the
warm air
to move. Also, instead of feeding the heat in at the
bottom,
where the coldest water is, the heat enters from the
top,
for the highest temperature to be near the warmest
water,
then exits at the bottom, where the coolest water is.

> A second water heater, on top, could be used to
capture
> more heat as a pre-heater

The preheater (if needed, to extract most of the heat
from
the air) would be "technically" below the other
heater, though
in the real world it could set physically next to it
or even above
it. It would only be down-stream from it in terms of
the air flow,
an up-stream from it, in terms of the water flow. It
would be a
classic counter-flow configuration. However, the first
tank in
the water flow would likely be a simple ambient heat
exchanger
tank, where a bare tank would warm the incoming ground
water
to room temperature. In my "Solar Loft" (new name)
designs,
there is a tank (or tanks) up at the peak of the heat
storage
attic, warmed by the sunspace air during the heating
season,
and by ambient air during the cooling season.

> First I question the efficiency of the Amcor Nanomax
A12000E.
> Assume, arbitrarily my room temperature is 75
degrees. The unit
> is inside the room so it does not have a condenser
sitting outside
> in 95 degree air. It's easy to remove the heat
because it is doing
> it at the expense of my cool room air.

The EER is the amount of cooling BTUs, over the amount
of Watts. EER is usually based on performance at 95°F.
Most of the air movement is from the room, then back
into
the room (after being cooled). The exhaust hose is
only to
carry the heat and moisture away, in what should be a
smaller air stream.

> Now what I thought-- assumed, might make the Amcor
> extra efficient

It seems to already be very efficient.

> was that the condesate water was used to help cool
> the condenser (instead of using my cool inside air).

That would require a continuous supply of cool water.
The maximum capacity of the unit is 38 pints/day,
which
is 1.58lb of water per hours, which would be a maximum
of about 1500BTU/hr if it were 100% evaporated by the
heat of the unit (not at all likely). The unit uses
829 Watts
when on high. That represents 2833BTUs. 1500 is 53%
of that. I think that is more than could actually be
evaporated,
because it would require boiling the water, which is
likely to
cause more heat loss. That 1500 BTUds would be when
the unit is aready putting out 12000BTU/hr, and
already
carrying the water away. That appears to me ( I have
not
done a caculation on it, that it would require more
room
air to carry away the evaporated water, than it does
to
carry it away as mist. However, I suspect that since
the reservoir is near the compressor, that there is
already at least some of the heat transferred
directly to the water, before it is misted.

> That way a problem (having to dump a bucket of
water)

There is no "problem" of dumping water. The unit
offers
two options. 1) there is a drain tube, which can be
run to
a drain, sump, or outdoors. 2) There is a misting
attachment
for the tube, and a place to locate it in the exhaust
tube, so
that the water reservoir never needs to be emptied by
hand.
The water goes out the exhaust tube with the hot
air......In
other words, the heat of the air may evaporate the
water,
but only as it is going out the exhaust tube.

> had been turned into an advantage (the superior heat
removal
> of water and the reduction of already cooled air
being wasted,
> by pumping it outside).

Amcor has another line of portable AC, the "AL" line,
which also have a swamp cooler function. You might
find those interesting
.
>If I understand you correctly the Amcor merely blows
> hot exiting air over the water, making it evaporate
and
> producing no cooling advantage.

No. The water is not evaporated.
It is misted into the exhaust air, inside the tube,
or it simply drains away, if a drain is available.

> That only wastes the water!

It is just condesate. The maximum is only 25oz/hr

> I could run a hose to it and use it to water plants.

Yes you could. That is one of the standard options
that they offer. The unit even pumps the water for
you.

> Why waste the water when it could help cool.

If your plants are in the house, then you are not
getting rid of the heat, that would be in the water.
The only way the 25oz/hr of water is going to
have a significant cooling effect, is if you
evaporate it, and exhaust it. Otherwise, you
will just have a little warm water, in your
house, releasing heat and humidity. Without
evaporation the water, will not be able to
absorb much more than maybe 30BTU.hr
I think the people at Amcor have a pretty
good idea of what is going on.

> Is the EER number a fraud because it is stealing and
> exhausting my already cool air and appearing very
efficient
> because it is in working in a cool room that it is
exploiting
> while pumping warm air in at the same time?

We don't know for sure. What we do know is that
compared to other portable units, it does more cooling
per Watt, and that there is nothing about the units
that
suggests it exhausts any more air than any other unit.

However, in both of the configurations that I have
proposed (1 extracting additional heat from the Solar
heat storage, and 2) heating water), that is not a
factor,
because neither requires air to be exhausted to
outdoors.
In those cases the EER should stand on its own. Plus,
the additional 2833BTU/hr that it takes to operate the
unit, also goes into the heating of the house or
water,
increasing it efficiency even more...to a COP of 5.24

However, there are still warnings: Quote:

"Buyer Beware! Not all BTU ratings can be trusted.
Just because the BTU's are stated to be high on
specific
air conditioning units, this does not mean it is
necessarily
true. Some manufacturers will exaggerate the BTU's on
units to raise the possibility of selling them and
others will
be more conservative to cause lower EER ratings, so
keep
in mind that a low portable air conditioner EER may be
mis-
-leading. It is best not to allow the EER energy
rating to be
your only criteria for choosing an air conditioning
unit.
Research the unit you are considering for your home
and
you will be happier with your purchase. If you have
any
further questions, please go ahead and give us a
call."

I have also noticed several online sellers, who claim
EERs that are very much higher than the manufacturers
rating, or than the BTU/Watts numbers posted on the
very same pages that falsely claim the exagerated
EERs.
But, the 14.46 EER for the A12000E is not the claim
of the manufacturer. It is the result of the claimed
BTU
output, and the claimed energy usage of the unit.
I calculated that EER.

Even if it is a slight exageration, when used
as heat pump the COP should still be around
five, which means getting five times the heat
out of it (for the same electricity), as with an
electric resistance heater. Even if it were only
double, that is a huge improvement, and for
most people would be lower cost heat, than
from any other conventional energy source.

I do not have a way to very accurately test
the energy output of the unit. However, the
only note I found, claiming that the Amcor unit
was not as efficient as claimed, was based on
the energy it used. I will be able to accurately
measure that.


-Laren Corie-
Natural Solar Building Designs, Since 1975
www.LarenCorie.com


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