mas985 said:
My roof is 25' high and yet a 1/2 HP pump still works.
Thanks again, mas985. Actually my roof is also 25' like yours - I misstated 22", which is the height of the roof above the pool level, which is elevated, but the pump base is 25' below the roof.
The crash course on pool hydraulics you wrote:
http://www.troublefreepool.com/hydraulics-101-have-you-lost-your-head-t915.html
is excellent - I should have read through it before to understand some of the things you were saying better.
mas985 said:
The FHPM 0.75 has a similar head curve to my pump so if my pump works with solar on a 25' roof, yours should easily work on a 22' roof. And as I pointed out before, I can bypass some of my water and still get high efficiency out of my panels. So I am very confident that impeller will work for you.
I was looking at the pump's head curve, and on high-speed at 0 GPM the 0.75 HP FloPro FHPM has around 57 ft of water head, which at a roof height of 25'+ is at least twice my height, so that looks perfect. I assume a FloPro FHPM 2.0 HP with a downgraded impeller to 0.75 functions like the native FloPro FHPM 0.75 HP, which I figure is what they refer to in the chart. And even though their 2-speed models start with 1.0 HP and up, I assume if I change the impeller with the replacement for the FloPro FHPM 0.75 HP 1-speed:
http://www.amazon.com/gp/product/B00564PVNG/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
it will function in a 2-speed capacity in my pump (FloPro FHPM 2.0-2). In terms of the flow rate using a 0.75 HP pump at low-speed, would that generally be sufficient in case I wanted to use the gas heater, which requires a flow rate of 30-125 GPM?
In case it helps, the plans for the pools state:
system flow rate: 75 GPM
max flow rate from pump curve: 130 GPM
total dynamic head: 27.99
Also, is changing an impeller relatively straightforward for someone who's never opened a pool pump before but is generally good mechanically, if I follow the directions? Or better to get someone to do it if there's some tricky part that could mess the whole thing up.
mas985 said:
Also, since you have such a large area of panels for the volume of pool water, you are going to find that you will not need to run solar for very long to maintain water temperature. I have 33% less panel area per water volume and I can easily get up to 10 degrees per day if needed. But on most days with a solar cover, I don't need to run solar more than 1-2 hours to get the pool back to 88 degrees. I think you could actually get away with 6 panels. Why do you have so many panels? I wouldn't think south Florida would require much in the way of solar.
I spoke to a Heliocol installer, who originally recommended 8 50-ft2 panels = 400 ft2. An Aquatherm installer rec'd 9 4’x12’ EcoSun panels = 432 ft2. When I mentioned to them that I was going to install a solar enclosure, which the basic screen blocks around 10-15% of heat, and on the east/northeast side and on most of the top I was going to install 80% UV/heat-blocking screen, and we'll probably add some degree of landscaping that blocks even more sun. So I specifically asked if they thought I needed more panels, they offered options of more: Heliocol to 9 = 450 ft2, and Aquatherm 12 or 14 4x10' = 480 or 560 ft2. So maybe they were all overselling to begin with and saw a chance to over oversell based on my question? Looking around this forum, I saw different opinions on the right amount to install, but it seemed that some got notably longer swim seasons w/ more panels and felt the more the merrier. Do you think I'm getting past the point of diminished marginal returns with 9 panels?