On Sat, 13 Feb 2016 15:43:24 -0500, "Mr. Luddite"
wrote:

On 2/13/2016 3:05 PM, wrote:
On Sat, 13 Feb 2016 13:48:34 -0500,
wrote:

On Sat, 13 Feb 2016 08:56:35 -0500, Justan Olphart
wrote:

OTOH I also have a 330k BTU propane pool heater I never use. I am
thinking about hooking that up to the spa. I should be able to put 40
degrees in the water in less than 20 minutes with that ;-)



If God meant you to be soaking in a hot tub or pool in the middle of
winter, he would have installed a hot spring under your house.

===

God heats those who heat themselves. :-)

Amen.
I just looked and it is 98! for free.
Lets see how it works when the ambient is more like 50-60.


When we were in Florida for the winters I fooled around with a
homemade solar heater for the pool. I got a 4x8 sheet of plywood,
cut it in half for two, 4x4 pieces and painted on side black.
Then I got some black PVC tubing and coiled as much as I could
of it on each of the pieces of plywood, attaching the coils with
plastic retainers. Connected the two coils in series and mounted
them so they faced the sun directly. I used a submersible pump to
run water from the pool, through the coils and then back to the pool.
Thermocouples were attached in the "send" and "return" lines.

During the day I'd measure about a 4-6 degree delta between the pump
side and the return side. It worked pretty good but it would take quite
a while to raise the pool water temp significantly and the losses at
night would wipe out any gain made during the day. Junked it.


When I had 240 sq/ft of collector it would make a dent in a 500 sq/ft
pool but when I cut that back to 160 sq/ft it wasn't worth doing most
of the time so I put in the plumbing to switch it to the spa.
It is a flip of a switch either way and it was good today on the spa.
I ended up with 99 degree water and that was about 20 over ambient.
Without glazed collectors and a better cover I doubt I can do better.