Posted by nicksanspam on March 23, 2007, 8:14 pm
The pipe is $0. A 2'x20' aluminum sheet for a 2' tall x 6' diam tank
might be $0, an 8'x8' 2" double-foil foamboard cover might cost $0,
plus $0 for EPDM plus $0 for the transparent top plus a $0 pump
plus 2 $0 thermostats.
This could make 100% solar hot water in December.
Posted by dbljay7542 on March 25, 2007, 6:02 pm
On Mar 23, 4:14 pm, nicksans...@ece.villanova.edu wrote:
Could you please explain how this all goes together.
Posted by nicksanspam on March 26, 2007, 11:34 am
The unpressurized tank stores heat for a few cloudy days in about 400 gallons
of 140 F water. Pressurized cold water from the house flows into the 300' pipe
and back to the house, warmer. The tank is surrounded with lots of insulation,
with foamboard on top, under a layer of black EPDM rubber draped over raised
edges to make a shallow pond. During the day, a pump moves tank water up a few
inches over the rubber when the cover temp is more than 140 F and the tank is
less than 140 F. The NSF PE pipe is rated for 125 psi at 73 F but tested to
600 psi, and it loses about 10% of its rating for every 10 F temp increase.
The 140 F limit protects it from bursting.
A reflective north wall can help in higher north latitudes. To store more
heat, we could add some lithium or calcium chloride to the tank water and
float a tub inside the tank that collects distilled water on sunny days
and evaporates water on cloudy days.
Posted by Joe Fischer on March 24, 2007, 12:24 am
On 22 Mar 2007 16:38:46 -0500, firstname.lastname@example.org wrote:
Nick doesn't read my posts, will somebody please
tell him the pipe coil should be laid flat in a spiral one
pipe thick, and a storage tank added indoors someplace
where the heat would not be a problem in summer.
There should be plenty of pictures, descriptions
and plans for DIY designs on google links.
Posted by Ulysses on March 23, 2007, 2:38 am
Currently I have about 150' of 1/2" black poly tubing coming from a small
tank to my house. It is fully exposed to the sun. By about 11:30 am on a
sunny day it is almost too hot for taking a shower. By 1 pm it is scalding.
With my unusual (self-employed) lifestyle I am often able to take a shower
when it's convenient so I can almost always take a shower using perhaps 90%
solar-heated water and there's always enough hot water for me but I don't
have a lot of hair to wash. OTOH I am planning on building a solar water
heater that'll do about 25-30 gallons in an insulated box with dual-glazing.
The exposed pipe cools off as soon as the sun goes down.