Radiant under pool, indoors

MBuck

I am planning to put a 21’ x 50’ x 4’ vinyl swimming pool recessed into the floor of my Indoor dock diving pool. Formed with concrete and them set the pool inside the recessed area. I would make this area its own zone. I would like to use this exclusively to heat the pool. I do use a solar cover overnight and when not in use, but the pool would be uncovered much of the day 6 days a week. 8-10 hours.
i will also have radiant floor heating in the remaining part of the building. 140’ x 60’ x 12’.
My questions are: is this an energy efficient  option, and where would I add a thermometer/thermostat to control the pool water temperature? 
Thank you!
Marie

Zman

Since you need to constantly filter the water anyway, the most effective to heat a pool is to put a heat pump, boiler, or heat exchanger in that loop.

It is possible to heat an indoor pool via radiant tubes, it would definitely be the "hard way" with no real up side.

hot_rod

With indoor pools, if the room is heated the pool load is reasonable for radiant. I tried a small outdoor swim spa with radiant and there is just not enough surface area to cover the load. It also depends on expectations for temperature recovery 

De-humidification is critical with inside open pools 

Paul Pollets

I've heated the pool deck with radiant loops a few times, but never the pool itself. There wouldn't be enough BTU's available to make a difference. As Zman said, pool heating is done with a heat exchanger, a dedicated boiler or a heat pump. Indoor pools require pool dehumidification systems.