I own an in-ground pool which has a pump for the pool (inline with filter and SWG) which can be switched to run 4 jets in the pool with or without the gas heater. My other 8 jets use a separate pump system which merely circulates the spa.
With our concern for efficiency these days, why does every PB run the same water heater which can be designated for either pool or spa circulation? I never want to heat my pool with gas, it would cost a fortune! I only want to heat my spa.
But all PB's seem to design it this way. I've heard from some "experts" that it's always good to circulate some water through the heater at all times. But why? It takes more plumbing and higher resistance to flow through a heater. Why not take it out of circuit when I'm circulating only for my pool?