[Strawbale] Sub Floor Radiant Heating littlehouses cross post

[Shody Ryon]

Q.... To save more, invest in a solar assisted ground
loop heat pump with hydronic underfloor heat.

A...In most cases having both Solar and ground source
for the same job, would be overkill, and the payback
would not be nearly as good as when just one of them
was used, because doing both requires a very high
initial investment.

Q...Go one better, just use solar, with a large enough
tank to hold enough heated water to cover cloudy days

A...There is yet another option. Instead of using an
expensive
ground loop as the source for the heat pump backup
heating,
use the Solar heat storage as its source. When the
storage is
too cool for using its heat directly, it is still much
warmer than
the ground, so the heat pump will be able to function
at an
even higher COP (Coefficient Of Performance) than a
ground
source system. Of course, the cost of running the heat
pump
to the Solar storage will be only a tiny fraction of
the cost of
a ground loop. Back in the 1970s and 80s there were a
few
overly complicated and very expensive Solar heat pump
systems built. But, heat pumps, in general, were not
very
efficient back then. Over the decades, since then,
heat pump
technology has progressed, and electric prices have
stayed
relatively flat compared to other heating fuels. So,
at this time,
the marriage of low temperature Solar collection, and
a heat
pump, is highly cost effective. It also removes the
need for
any fossil fuels, with their monthly base rates, and
leaky
flues, that continually pull warm air out of your
house.

I am presently starting to use small heat pumps
with my sunspace houses, and their heat storage
attics.
I have two such houses under construction, right now.
Basically how it works, is that when the heat storage
drops to a temperature that is too cool to either
effi-
-ciently, or comfortably blow enough air, or pump
enough water to warm the living space (which just
happens to be typical air conditioning temperatures),
the heat pump simply "air conditions" the heat
storage,
with its heat exhaust tube running to the living
space.
With a small 14,000 to 15,000BTU unit, costing less
than $400, it can get a COP of over five (five times
as much heat, per kWh, as electric resistance heating,
including the electricity to power fan heat
distribution).
That is ground source heat pump efficiency, at only
a tiny fraction of the initial cost. It also
effectively
just about doubles the Solar heat storage capacity,
while allowing the sunspace (or air type Solar panels)
to collect at much lower temperatures, therefore
more efficiently.

Q.... I use a regular heat pump and wood stove

A..You could take advantage of a simple heat storage
for
your wood heat, and a small, low-cost, heat pump/AC
located in the heat storage area, will offer the
option of
it heating the house for a much longer time, between
fires, or when you are not at home.

Q...I live in the frozen north, and would love to find
> an alternative way to heat my house, all electric.

A..Rather than usng hydronic Solar panels, you can
build
a simple low-mass, single glazed, sunspace. It need
not
be super insulated, because it is only warm when the
sun
is heating it. You can build it like a porch. Or, you
could
use simple vertical wall air type collectors. Either
way,
if you want a larger percentage of Solar heating, you
will
need a heat storage. I suggest using bottles of water,
which store a lot of heat for their weight, and act as
their
own heat exchangers. In the attic is about the best
place
for such a heat storage, because it does not take up
floor
area, and the sunspace heat will rise to it, without
the need
of an air mover, or dampers, or automatic controls.
When
the living space needs some heat, you just bring a
little of
the warm attic air down, with a small fan or water
pump.
When the attic air is not warm enough, you "air
condition"
the attic with a portable air conditioner. These
litttle units
have an exhaust hose to blow the heat to outdoors in
summer. In winter, when using it to heat the house and
"cool" the heat storage, it blows its hot air down
into the
living space. The result is that you get over five
times as
much heat from the electricity that it uses, as you
would
get from an electric resistance heater.

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

-LittleHouses-
http://groups.yahoo.com/group/LittleHouses

-Energy Self-Sufficiency Newsletter- Free at
www.rebelwolf.com

-WoodGas- Power from Wood.
http://groups.yahoo.com/group/WoodGas

-Refrigerator Alternatives-
http://groups.yahoo.com/group/RefrigeratorAlternatives

-Laren Corie-
Natural Solar Building Designs, Since 1975

-Energy Self-Sufficiency Newsletter- Free at
www.rebelwolf.com

-WoodGas- Power from Wood.
http://groups.yahoo.com/group/WoodGas

-Refrigerator Alternatives-
http://groups.yahoo.com/group/RefrigeratorAlternatives





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