Hi Capt,....I've been doing testing of this sort for the last 4 days now .There really isn't much difference,by 1:00 in the afternoon my stored water is up to temperature.
1st day ...2min pump every hour on the hour
2nd "....15sec pump every 15min
3rd "....45sec pump every 30 min
So on and so on....the short quick (2nd day) seem to bring the temp up a little quicker, but like I said by 1:00 their all the same.
The 2nd day would see the pump running the least amount of time, but it starts and stops 4x as many times as say the first day,but somebody with better math skills or experience would know better than me which would be more efficent.
Probably the most effcient thing would be a temperature sensor saying when to circulate, but I could only find such a valve almost 2 hours away from me and the guy said it was around 300 dollars........so 30 dollar programable timer is what I'm going to do.
I'm sure there are cheaper sensors' out there but being on dial-up I can't waste the day surfing the net.....good-luck....artv