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why remains on till beyond midnight

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Posted by stephenjprice@googlemail.com on June 2, 2007, 12:20 am
 
hi we have south facing solar roof panels that are still collecting
heat and pumping 3 hours after sundown. how?
is it latent heat from roof space or what?


Posted by Morris Dovey on June 2, 2007, 12:16 pm
 
stephenjprice@googlemail.com wrote:

| hi we have south facing solar roof panels that are still collecting
| heat and pumping 3 hours after sundown. how?
| is it latent heat from roof space or what?

Panels should collect /some/ heat as long as outside temp is warmer
than water temperature, and as long as there is sufficient indirect
sunlight (open-sky radiation) to provide warming.

You /may/ be collecting some heat from your roof space, but this may
be an indicator of inadequate insulation somewhere.

You /may/ have a missing/faulty check valve that allows already heated
water to circulate back to trip the pump control sensor.

You haven't really provided enough info for a good answer.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/



Posted by Mark Schofield on June 3, 2007, 3:59 pm
 that happens with my system occasionally. if the panels are 4 degrees hotter
than the water at the bottom of the storage tank (where the sensor is) then
the pump will come on. So if you drew a shower at night with an
outside/panel temperature of 70 and the water coming into the tank was 55 or
60, then the pump would start. you aren't measuring the presence of
sunlight, but only the difference in temperature between the tank sensor and
panel sensor.some controllers have an option to disable circulation if the
panel temp is below a certain point(ex: 70 degrees)


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