There seems to a hung jury when it comes to the position of the main drain/return line when heating the pool. The general consensus is to keep the system on main drain for normal pool operation, thus keeping the dirt and debris in the hopper to a minimum. I have my own opinion on what position to have it in, but I can neither confirm or deny if that is correct or not. which is the more efficient and effective method of heating the pools water. (1) Pulling cold water from the bottom of the pool and returning it to the top. (2) Pulling water from the top of the pool (skimmer/s) and returning the heated water to the bottom of the pool. I would be interested to hear any and all opinions as well at as any technical in formation specifically in the area of thermodynamics and heat distribution.
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True, true and true, nonetheless a well aimed ( downward) return even though placed at the usual height on the wall will bore through the pool water and send filtered heated water into the depths of the pool even at low velocity. Older "three pipe" pools usually suffer from a lot of dead spots.
Robert Witkowski said:
That is my thinking as well, using the main as a return will create a condition of uniform water temperature , regardless if the heater is on or not. When using the main as a suction, the hopper will stay cleaner, (especially if there is a vac with a sweep), but the water temp is inconsistent. There is nothing worse than diving into a warm pool and hitting that cold wall of water in the deep end.
I think that given the choice you would be better off returning to the floor...
The analogy that comes to mind deals with a candle. You can very easily blow out a candle, BUT it is much more difficult to suck enough air in to cause the candle to extinguish.
This is the same argument that is being used to refute the effectiveness of main drains to circulate a pool. Water is far easier to move around with return fittings, than it is to move around by displacing it with a drain.
How often have you had DE or other dirt back up through a 2 port skimmer and end up on the floor of the pool? When you close the diverter valve to "suck up" all that DE, you end up with virtually no dirt removal at all, (usually only within a couple inches of the drain at best), so how effectively are you moving the water at the bottom of the pool through displacement?
Just a thought, I have no testing or data to back any of this up...
You're over thinking it. Heat loss occurs at the surface. My experience is that distribution of water has little effect. Protecting the surface from wind is your main consideration. In an uncovered pool, suction and return should be adjusted to provide the most efficient circulation. Hope this helps.
Bill