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Solar Thermal Design For Historic Home - Page 5

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Posted by nicksanspam on August 18, 2006, 9:36 am
 
 

Orangerie. A house that makes oranges. Often iron and glass,
in Victorian times. The Crystal Palace was a nice example.

Nick


Posted by SJC on August 19, 2006, 3:18 am
 


  I have thought of a sun room, such that low winter sun come in the side
to heat and light the room and also shines on the roof, where there are solar
thermal collectors.
  I would make the room and the collectors air collectors for the house during
the day and store large amounts of warm water to use at night with a fluid
source heat pump.



Posted by Jeff on August 19, 2006, 6:00 am
 SJC wrote:


   I don't think the fluid source heat pump makes sense. You can't get
more BTU's out of the water store with the heat pump than are there. All
you can do is get it to work when the water is too cool to heat by
itself, but you pay a high price for that, and you waste some BTU's in
losses. It makes more sense with a finite heat store to just use heat as
is. Radiant floor heating springs to mind.

   Jeff


Posted by SJC on August 19, 2006, 6:16 pm
 

BTU's out of the water store with the heat pump than

by itself, but you pay a high price for that, and

to just use heat as is. Radiant floor heating springs

  A fluid source heat pumps can have a good COP if the water is say 70F to 90F.
This is the principle behind Ground Source Heat Pumps where the ground is say
50F to 60F. It you look at efficiency curves for collectors, they become less
efficient
the higher the delta between air and water. So with water collectors operating at
90F on a 50F day, you can collect quite a bit of heat.
  I know lots of people will trash this idea as well as any other idea that does
not
fit with their opinions. But I can tell you one thing I feel is certain, if we
do not
all start working with one another to get millions of people on the right energy
track, we will have many more problems than we can handle very soon.



Posted by Jeff on August 19, 2006, 10:37 pm
 SJC wrote:


BTU's out of the water store with the heat pump than

by itself, but you pay a high price for that, and

to just use heat as is. Radiant floor heating springs

efficient

Thermodynamics is not something that I've mastered but...

<URL: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html  >

You are just moving heat with a heat pump, what it does is raise the
temperature of that heat. You are not gaining any heat. If you have a
COP of 3, that means that 1/3 of your energy (all of the electricity) is
being lost. (Normally that's good because you get 3 times as much
useable heat) Heat pumps make sense if you have a nearly inexhaustible
reservoir. I think you'll have a real problem when you tap out that
solar rervoir.

   It makes more sense to use that reservoir as is. You can't do that
with forced air, but you could with underfloor radiant.

   I'm not saying you can't do this (solar sourced heat pump), it will
work, but you are just spending a lot of money (and electrity) to make a
high temp system function when you could just install staple up radiant
heat (with *wide* aluminum heat diffusers) for less money.

You'd want to max the thermal contact area and minimize any carpeting to
keep your temps as low as possible.

That's the way I see it. I have an imperfect understanding of radiant
floor heating but it seems well suited to the temps you get from flat
plate collectors (100F or so).

   At any rate, I'd run some numbers and see what you come up with with
your solar source heat pump.



does not

do not

energy

  I agree 100%.

   Jeff


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