I am designing my own in ground spa for my cabin. I am planning on running my heater, compressor, filter system, etc out of my well/pump house in the corner of my garage. I will be running the supply and return lines underground well insulated and wrapped in reflective sheet metal.
Notes:
-Tub will be used infrequently and during winter months completely drained and filled the day before use
-Heating will only be turned on prior to use/planned trips and I would like to reach temp in less than ~12 hours
-I have unlimited electric supply available, but gas requires me bring it with me, so I would like touse a heat pump.
Design:
-9'x9' Surface Area
-Depth Average of 3'8"
-Volume, minus CIP Seats and Steps is ~2000gal
-Elevation 6000' (southern Idaho)
-Temp desired (104°F)
Question:
-Will a heat pump work? Even during winter months? My idea is to have the pump draw fresh air and exaust outside through a duct system in the summer, but in the winter months I was planning on closing this loop and haveing the supply and exhaust be the pump room with a closed circuit except for minimal exchange under the door to the garage.
-What size of heat pump if possible to heat my 2000gal tub from well water temp ~55°F to 104°F in 12 hours or less during winter months? Would be using 6" ridgid insulation cover.
-If a heat pump won't work and I need propane: what size would I need and what is the average consumption in gallons for the heater? I could feasibly bring a 30gal propane tank with me every time I go to the cabin, but I would rather not.
I appreciate all comments and any help received. I am concerned that a heat pump just isn't going to get the job done and I don't want to start building the thing if it won't work when done and gets converted to a sandbox for the younger adults and pets.
MW
