On 26/06/2011 9:58 PM, Andy Burns wrote:
Vortex10 wrote:

GREEN is temp top of XCel. Each upward jink is a boiler burn.
BLUE is solar "flow" temperature
PURPLE is solar "return"
RED is temp at bottom of XCel

I assume the return temp is measured close to the store, rather than
close to the collector, by the fact that it remains warmer than the flow
temp overnight.

Yup. Just before the pump. About 2 feet from the store.

Flow sensor is on the roof.


But how does the return get to be colder than the bottom of the store
during the day?

I've noticed that. I don't know how the indirect coil within the XCel
is constructed but I believe it goes lower than the sensor pocket.

ALSO I have solar PV and put together a setup to divert surplus leccy to
the XCel, rather than export it. Mentioned about 2/3's down the "Solar
PV --- so anyway" thread. There's some interaction going on.

ALSO the red PRT is a dodgy Chinese device from Ebay. I've been meaning
to try another.