I have the Pentair Ultratemp 140,000 btu with chiller option for my 26,000 gallon pool. It does work - I live in South Florida and I had it running June, July, August to try to maintain a 87 degree pool. Got a little pricey in electric but was worth not having to swim in a bathtub. In regards to noise - it is no louder than you A/C system for your house (maybe it is more quiet, depending on age of your A/C). I have not used the heat portion of it yet as my pool is hovering around 84 degrees now. Couple of things with the automation (intellicenter) from pentair and the heaters.....I run a heat pump/chiller AND a 400,000 btu Mastertemp. They are plumbed in line and hooked up to the intellicenter via RS-485 cable. The automation is supposed to regulate temperature via the heat pump 1st - if it can not maintain temp it reverts to the gas heater. But after that it does not go back to the heat pump to maintain. You have to switch it manually - Stupid in my opinion -
Also, when in chiller mode Pentair forgot to link the temperature differential up to the chiller portion. So if you have a chiller set point of 87 degrees, and your temperature bounces back and forth between 88 and 87 degrees - your fan will cycle on/off, on/off, on/off until the temperature is a constant 87 degrees. That my friends, will burn that fan motor up in no time!!!!
So, research your automation, research your heatpump - get the biggest you can fit- and make sure they all talk to each other!!!!!
Or hook it up to a relay and control it through there!