My solar hot water system's circulation pump seems to be running itself at night for short periods. I don't want it to do this because it will be wasting hot water as it gets sent through the cold panels.
It may be the freeze-prevention system kicking in, but it happened in the summer too. Or it may be something else.
The controller unit is not very sophisticated, with a limited, menu, history & no socket to plug a PC in, or network connection.
I want to be able to monitor the water pump for a period of time to see how much it is running in hours of darkness. And maybe plot the results to see if it is regular.
Can anyone think of a cheap, nifty way to do this, that doesn't involve me sitting under the floorspace all night with a stopwatch?
I have a PC just a couple of metres away - I was thinking some sort of sensor that would pick up the electric current flowing when the pump is running?