How effective are heat pumps for spas?
Signing a contract for an in-ground pool and spa in Central New Jersey. Pool will be approximately 700 sf (20x40, 6 ft deep), the spa 49 sf. of surface area. The contractor is recommending an AquaCal Heatwave H120 (110K BTU) heat pump instead of a propane-based heater (I don't have access to natural gas).
My primary concern is the spa. It would be nice to "extend my season" but I want to make sure I can get the spa up to 103 degrees within a reasonable time when I want to use it. By default it will be circulating with the pool using the same equipment so it will have pool temp water except when the system is changed to circulate only the spa.
I have read completely conflicting things about how effective heat pumps are at raising temperatures (including the mega-post here that turned into a debate about the physics of how they work). My focus is, will it get my spa to 103 if the outside temp is say 70 degrees and how long would it probably take? The pool guy says 45 minutes tops, but I am dubious.
Also, how long would it really extend my pool season in Central NJ? He said April to November but that also seems aggressive, given temps could be in the 50-60's. I have a friend who got a pool and heat pump last year in Long Island who says he couldn't get the pool to 82 degrees if the temp was below 70 degrees outside. He didnÃ¯Â¿Â½t have a hot tub though so I couldnÃ¯Â¿Â½t ask how that went.