You can put nicheless in any pool they screw into a return style fitting. Gets pricey but looks the best. With square pools you want to pay attention to spacing and equalness they flow better that way.
Wow I like this website - I wasn't aware of this new trend. Yeah it adds up but it might be worth it. The fact they screw in in a return is genius. I'll prepare a plan.
You have to be careful if you plan to insulate. There are proper techniques none of which are easy. An auto cover excels and the ground is good insulation.
Well here I respectfully disagree; earth temperature is about 13C or 56F in this area. If I target a water temperature of 30C or 86F, there is a pretty big differential.
But let me go in order and see if it makes sense. I would divide heat losses in:
- evaporation
- through the cover
- through the walls into the dirt
Evaporation
I have been told that evaporation with an autocover pool in this area is about half an inch per month during swimming season. On a 18*36 ft pool that is almost exactly 200gal/month or 757 liters (and kg) of water. Water's heat of vaporization is 2260 kJ/kg that means 1.7GJ/month, 1.6M BTU/month or just about 53k BTU/day.
Cover
I read an assumption that the cover has an insulation value of R-1. 24-hour average temperature of air during the swimming season in this area should be around 60F (Yes it's never too warm, we do not have AC in the house). Target water temperature we said 86F. According to Wikipedia
R-value is defined in US as (°F·ft2·h/BTU). This means losses will be (86-60)F * (36*18)sq ft * 24h / 1R = around 400000BTU/day
Walls
Let's be generous and give dirt a value of R-2. This is quite optimistic according several tables I have found, but the first 3-4 feet will have gravel, then there is some plaster between the dirt and the liner so let's use that value. This assumes good drainage, something I'll have to work on. After tedious analysis of the dig sheet, turns out the pool should have an internal surface of 1030sq ft. Using the formula above, with dirt temperature of 56F: (86-56)F * 1030sq ft * 24h / 2R = 370000BTU/day, almost as much as through the cover, (but probably more). Assuming one could put some sort of foam that has an R-10 the number becomes 74k BTU/day.
To put things in perspective, I need to consider the heat budget by estimating the contribution from the solar panels. I have not done this part of the analysis yet but I read a panel can deliver up to 40000BTU/day, so by insulating the pool it's like I have 7 more panels on my roof.
You need 2" or more of ridgid foam to make a difference. Most insulated pools are concrete and are made from ICFs
Yeah I was thinking about 4" of insulation but 2" might be enough.
I welcome feedback on my numbers.