Monday, April 12, 2010

Efficiency related to pump speed?

12 April: I have been having a correspondence with Dr Chris Wood, and he is suggesting to Increase the Trigger Temperature Difference from 3.0 to 5.0 degs C, and  Increase Pump Speed.
    We could justify running the pump faster, because the sunbox pump would be pumping for fewer hours, and would more efficiently send heat down below while the heat was there. If the boxes cool more quickly as a result of more efficient sweeping of heat from them, then the pump goes off until the next time that the temperature difference rises. This higher temp. diff. would make it more responsive to sunlight which is a benefit, as we know we have free photovoltaic power when the sun is shining.

13 April: On the first day of faster pumping, we had about twice the usual amount pumped round, and a lot of energy pulled in - but then it was a record day of sunshine with the highest ever since the PV system was installed. I shall leave the faster pump-speed and higher temp.diff. on for a week to compare the difference. If it's better, it can stay.

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