I have tried to find out more information online about heating a hot tub with an OWB but I didnt find much. I'm sure it can work but I am wondering on the heat demand of the hot tub. I also don't see many people using it for this application.
I would be using a CB 6048 to heat domestic hot water 65 gallon side arm, 3000 square foot insulated house and the hot tub. Winters here can drop to -25 at night.
My bad if this ? has already been asked, I did try to search for my own answer.