Ventillation For Indoor Hot Tub

[soakmyfeet]

We are planning to put on a sunroom and bring our hot tub inside so it can be used year round (we live in MA and don't want to use it or maintain it outside when it's below freezing)

We know ventillation is important, both to control miosture and ventillate chemical gasses. The question is How MUCH ventillation, and what type?

The room will be an 11 x 16 mostly glass room with sliding windows on 3 sides. The 4th wall, the wall adjoining the house has a picture window and glass exterior door, so the room will be thermally isolated from the house and have a separate heat source. The tub is 7x7, and used for 1-2 hours/every day (i.e lots of steam!). We likely will keep the windows to the outside open in the summer, but will not want to when it is cold out.

We were told by an HVAC sales person (not the sunroom vendor) that a rule of thumb for ventillating hot tubs is: 10 cubic feet/min for every square foot of tub surface. For our 7 ft tub (49 sq ft), that would mean a fan that puts out 490 cu/ft/min is necessary. Does anyone have knowledge or experience to confirm this? We are concerned that the "rule of thumb" is for average hot tub use and not taking into account the heavy use it gets.

This is the humidistatic fan the sunroom vendor usually installs for hot tubs, and customers I have talked to say it takes care of all the excess moisture- granted they only use their tubs 20 min/day, not 1-2 hrs:

http://www.tamtech.c...ite,Product.asp

Another concern with the humidistatic fan is that it also will be sucking heat out of the room. Great in the summer, not so great when it is 10 degrees out and we are trying to heat the room. We are considering using a heat conserving unit (basically a heat exchanger that takes the moisture out of the air and puts the heat back in.) Does anyone have experience with these? Any advice or suggestions for units to check out?

Thanks for your input!