I wonder if anyone has thoughts on improving the heating efficiency of
a normal heat pump by warming the air around the outdoor unit? It seems
like a "poor man's" version of the geothermal heat pumps to me.

Here's the idea. For a few $ build a passive solar water heater with
antifreeze in the water. Let the water circulate through radiators
positioned around the standard outdoor heat pump.

Of course you could more directly use the energy in your house but that
requires modifying the inside, things the wife might not approve of.
Heating the air around the heat pump could all be done outside with
cheap surplus parts.

Possibly not worth the trouble but it might make a fun experiment.

gb

I've often wondered similar things, but usually after some careful
consideration, I've abandoned such ideas. The first thing that comes
to mind about this is that you probably don't want to obstruct the
airflow in or around the AC/heat pump unit, which is exactly what your
radiators might do - unless they're far enough away to not block the
airflow, in which case they'll be too far away to do any good.

Now, if you've got a real interest in solar heating, you could consider
piping the heated water/glycol solution into the basement and using it
to preheat your water prior to the water heater. Some internet
searching might even yield up some plans for such systems, and
depending where you live might you might find some government
incentives for installing a solar system.

Why not add solar panels to offset the heat pump's power use?

Probably the initial $$$ of the panels and other equipment necessary
for it. At least this is what puts most people off when thinking about
solar power. The solar hot water is much easier to build panels for I
think, almost to the point of being within the realm of a DIY project
for a really well-informed and ambitious person.

"louie" wrote in message
oups.com...
Probably the initial $$$ of the panels and other equipment necessary
for it. At least this is what puts most people off when thinking about
solar power. The solar hot water is much easier to build panels for I
think, almost to the point of being within the realm of a DIY project
for a really well-informed and ambitious person.

When I was in college I made a solar water heater for the trailer I was
living in. It consisted of a 4 x 8 box with insulated sides and clear
plastic on the top. Inside was 500 feet of 1/2" black plastic hose. It was
plumbed into the bottom of the water tank and worked with no power as a
thermosiphon. Even on cloudy days we got 170 degree water out of it. Plenty
for the three of us. However when it got a kink in it one day, I came home
to a leaking box and a blob of melted plastic. Never underestimate the power
of the sun!

LJ

According to Old_boat :

"louie" wrote in message
oups.com...
Probably the initial $$$ of the panels and other equipment necessary
for it. At least this is what puts most people off when thinking about
solar power. The solar hot water is much easier to build panels for I
think, almost to the point of being within the realm of a DIY project
for a really well-informed and ambitious person.

When I was in college I made a solar water heater for the trailer I was
living in. It consisted of a 4 x 8 box with insulated sides and clear
plastic on the top. Inside was 500 feet of 1/2" black plastic hose. It was
plumbed into the bottom of the water tank and worked with no power as a
thermosiphon. Even on cloudy days we got 170 degree water out of it. Plenty
for the three of us. However when it got a kink in it one day, I came home
to a leaking box and a blob of melted plastic. Never underestimate the power
of the sun!

According to one article I read, simple solar panels like this capable
of up to 400F, so, some care is needed in design to avoid blowouts or
meltdowns. Ie: pressure relief valves.

I've seen a design which consists of a similar box.
The innards consists of two 3/4" headers, one at either end, with 6 or so
3/8" lines running between the headers. The plumbing is all copper,
is soldered to thin copper sheet, and the whole thing painted black
and inserted in the box. Kept the costs down by silver soldering
the copper instead of using fittings. Cover is preferentially glass.
Various slight improvements, ie: a fiberglass or rockwool insulation
batt under the copper, thermopane glass, etc.

Parts cost around $100-150 per unit (cheaper than 500' of 1/2" PVC ;-)].

There are also at least two different manufacturers of an inexpensive
solar unit - mainly used for pools. 2x8 panels made from recycled
auto tire rubber with the water lines molded into it. If I recall
correctly, $100-150 or so each.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Wouldn't it be easier to just build a mini greenhouse over the
compressor that you could remove during the summer?

Or

just get some mirrors and use them to aim the sun at the compressor?

"louie" wrote in message
oups.com...
I've often wondered similar things, but usually after some careful
consideration, I've abandoned such ideas. The first thing that comes
to mind about this is that you probably don't want to obstruct the
airflow in or around the AC/heat pump unit, which is exactly what your
radiators might do - unless they're far enough away to not block the
airflow, in which case they'll be too far away to do any good.

Now, if you've got a real interest in solar heating, you could consider
piping the heated water/glycol solution into the basement and using it
to preheat your water prior to the water heater. Some internet
searching might even yield up some plans for such systems, and
depending where you live might you might find some government
incentives for installing a solar system.

For the life of me, I can't think of the name, but company out there that
makes a heat exchanger pipe that goes on the sewer drain line that will
preheat the water going to the water heater.

Here's a link to a site that mentions that HX.
http://oikos.com/esb/49/gfx.html

AND here's the link! http://gfxtechnology.com/