Ventilation for spa indoors

[johnvb]

   Question to anyone here who has experiences in installing a spa indoors.

How many air changes per hour is needed to be moved out of the room, while the spa is open and fully running at max temperature.

I'll be installing a mid-sized spa (7’x 7’) in a 12' x 12' x 8' room, using 100% outside makeup air, with manual switched control, and no extra heating or cooling for now. Room is totally sealed from the rest of the house (converted screen-in patio to low-e doors and windows).

Any "rule of thumb"? Should it be sized like a large master bathroom, a kitchen, or something totally different?

According to the second method of calculation from the web site linked below:
12 x 12 x 8 = 1152 divided by 60 =19.2 CFMs needed to change all the air in 1 hour, x how many changes per hour?

My thinking is the bathroom rating of 8 changes per hour should be plenty.

Thanks
John

http://www.panasonic.com/consumer_electronics/bp_ventilation_fans/size_ventilation.asp

[JLB]

My tub is inside also, I built a 14'x26' "sunroom" addition. The ceiling height is about 12', I  have many large windows,
  6 4'x 6' sliders. I  installed a 300 CFM  vent fan. I find that with jets and diverters on high that I easily keep the room ventilated. Somtimes I don't even use the fan and just open the windows and turn on the ceiling fan. I took precaution to seal all of the wood and trim because of potential moisture. I installed a propane fire place which is very nice in the winter. I'm very happy with the way I engineered the room.   The more air you can move the better. By the way, the fire place is vent free and it has an oxygen sensor, I was worried  I might evacuate to much air so maybe having the stucture to tight  could be a problem. Good luck!  

[johnvb]

 Thanks. I was thinking 300 CFMs also, with a variable speed control to turn it down if necessary. I'm considering one of the fantech brand attic-mounted remote ventilators, with multiple inlet grilles mounted in the ceiling, for less noise.

I'm installing 6- 40 x 60 double hung windows, with outside screens. I figure I can open the bottoms and/or tops to get the kind of cross ventilation I need, depending on the wind direction and speed.

The room overlooks a small lake, and in the winter, if the winds are gusting, it can be quite brutal. If the windows are open on the tops, the wind should just blow right over us (we’ll see  ) In the summer, that breeze is a welcome relief.