Domestic pool turnover rates

[Anonymous [GDPR] European in the UK]

Hi Richard and Carl, sorry been away for a while.
Yes Carl, understand the physics and apologies for not explaining clearly what I meant although I get the feeling Richard understood.
It's tricky to use a the car engine analogy as there is far more heat available to get rid off so transference would be faster courtesy of 1500 high energy, high temperature explosions taking place every minute but the thermodynamic rules are essentially the same I believe. It's more that actual application on a swimming pool where the solar energy is considerably less as is the temperature (geographical situation may of course alter that if you are in Arizona, California or over my part of the world).
Carl you said "Would you rather have a flow of 10 gpm with water that's 5 degrees (F) warmer, or 1gpm of water that's 25 degrees warmer? Which has more BTUs".
Obviously we are looking for the maximum BTU's where possible but are those actual figures for what you receive or just a statement to explain your point?

My point is that in Richards example the flow rate is 48 GPM which maybe more efficient in terms of the energy gain from panels only (though I doubt it) but doing that costs him on the pump electricity an additional 1275 watts (equal to over 6kw via a air to water heat pump). Slowing the water flow through the panels as Richard has shown reduces the panels heat efficiency by a small amount but like wise reduces the electricity by a larger amount so the overall efficiency is greater.

Richard assuming the 100% or near as is achieved at 48 GPM on your setup then 80% at 4GPM/panel then the electrical saving by slowing down the flow would save considerably more although the panels would get a bit warmer they won't go passed the outside temperature as that would be equilibrium?

Finding via a graph the best point for low electricity usage to the pump and the best flow for the panel is really what I was driving at so the slower flow around the panels gains more heat energy is absorbed which may not be as efficient as faster but is more efficient when the pump electricity is also considered.

On the best pool setup I have done (not the cheapest in capital outlay terms) the flow rate on filtration is 52.8 US GPM on 81 watts with plumbing lengths about half of yours Richard. The owner is planning to use solar (Evacuated tubes and heat exchanger) so this will impact on the overall efficiency so your data is helpful, I would prefer him to use a heat pump as the headloss is a lot less so allowing him to keep the running cost to minimal but some data is needed to back up that discussion.