Which type of roof fan or venting should I use? turbine, down-draft, or up-draft ?

funkpelts

Member
Jan 8, 2017
12
Muscatine IA
We moved into a house a couple years ago with an indoor pool and hot tub area. There is a FanTech updraft fan at the peak of the roof and another spot where a 2nd fan was removed at some point. It is a 12 inch opening and I would like to put in something when we redo our roof in a couple months. The fan that is there seems to be a down draft model, but wouldn't I definitely want an updraft model if I am trying to get heat out of the building mostly in the summer time? It runs on a temperature switch and during the colder months I wouldn't run it at all of course. We live in Iowa.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,031
Tucson, AZ
Does the make-up air for the room come from the outside? Is there an independent HVAC system for the room or does the room just get its environmental control from the rest of the house?

Indoor pools always present a complicated air-handling scenario - it all depends on what you want and how much you’re willing to spend. Have you ever, or would you consider, calling in an HVAC company for a consult? Pool rooms are a special beast so you’d need/want someone with experience in that.
 

funkpelts

Member
Jan 8, 2017
12
Muscatine IA
The area doesn't have any air temperature control besides some skylights we can crack open in the warmer months and these fans. I originally assumed the fans were blowing air up and out of the roof but when I look for these online I find ones that look exactly the same and they are described as down-draft. My roofing contractor is willing to deal with fans but I was wondering if there would be a usual rule-of-thumb on fans like this in a pool area. I live in Iowa so the local HVAC places probably wouldn't have a lot of dealing with indoor pool areas but I wish they did.

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This is what I have currently-
Products | www.fantech.net

And this is what I am thinking I should have instead, although I don't like the "cup" shape that looks like it would fill with water on my roof. How is this a roof fan?-
Products | www.fantech.net
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,031
Tucson, AZ
Well, here’s the thing - even though it sounds counterintuitive, at a fixed temperature, warm moist air is less dense than warm dry air. So one would expect the humid air generated by the pool to rise and, if natural air flow exists, it would go out the skylights.

The question is one of make-up air and where you get that air from. Is the fan intended to supply the makeup air or is it intended to exhaust air in the room? Are there any windows, doors or passive vents to the outside?

Maybe a sketch of the room would help...
 

Rollercoastr

Gold Supporter
May 18, 2016
866
West Bloomfield, MI
My fan exhausts. It's manual and variable-speed. Make-up air in my house comes from a large vent in the utility room. I wish the flue for the pool heater in that room could be fitted with a heat-exchanger to heat the replacement air, but as it stands, the running pool heater helps off-set some of the cold incoming air. I use my pool exclusively in the winter. I keep the pool covered when it's heated, and I keep the fan running while swimming. That strategy mitigates moisture issues very well, but at the (literal) expense of sending tons of hot moist air outside in winter. :(

I've found that swimming when the temps are single-digit or below isn't worth it. No matter how warm I get the pool water, cool air hitting us in the face isn't pleasant.

I'm curious about your heater. My pool isn't much smaller than yours, but my heater is a 200 compared to your 400...!?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,031
Tucson, AZ
All heaters will use the sane amount of energy to heat a specific volume of water, the only difference is how fast it can do it. My MasterTemp 400 was only a few hundred dollars more than the next smaller model when we built the pool so it just made sense to go big. It’s very nice to be able to heat the spa in 20-30mins.

Have you considered using a large room dehumidifier in the winter to try to control humidity? The output would be warm dry air and condensate water. The condensate could be directed back into the pool or down a drain. Definitely would cost a pretty penny to run that but it might be better than sucking in frigid air :scratch:
 

funkpelts

Member
Jan 8, 2017
12
Muscatine IA
I don't worry about the colder months as much, I just close all windows, skylights and keep the roof fan off. I am more worried about the warmer months when the ceiling surely gets insanely hot.

All heaters will use the sane amount of energy to heat a specific volume of water, the only difference is how fast it can do it. My MasterTemp 400 was only a few hundred dollars more than the next smaller model when we built the pool so it just made sense to go big. It’s very nice to be able to heat the spa in 20-30mins.

Have you considered using a large room dehumidifier in the winter to try to control humidity? The output would be warm dry air and condensate water. The condensate could be directed back into the pool or down a drain. Definitely would cost a pretty penny to run that but it might be better than sucking in frigid air :scratch:
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The house came with a 150k old Hayward and it wasn't heating fast enough except basically when you don't need it in July and August. The house came with a 415k nat gas supply and once I saw that I decided to go with 400k for the pool and 200k for hot tub. I am careful not to run anything else nat gas while the pool heater is running though. I bought these heaters on Amazon and they were only 1400 for the Trane and 800 for the StaRite.

My fan exhausts. It's manual and variable-speed. Make-up air in my house comes from a large vent in the utility room. I wish the flue for the pool heater in that room could be fitted with a heat-exchanger to heat the replacement air, but as it stands, the running pool heater helps off-set some of the cold incoming air. I use my pool exclusively in the winter. I keep the pool covered when it's heated, and I keep the fan running while swimming. That strategy mitigates moisture issues very well, but at the (literal) expense of sending tons of hot moist air outside in winter. :(

I've found that swimming when the temps are single-digit or below isn't worth it. No matter how warm I get the pool water, cool air hitting us in the face isn't pleasant.

I'm curious about your heater. My pool isn't much smaller than yours, but my heater is a 200 compared to your 400...!?
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Yes, bigger is nice now that I have these new heaters. I can raise the pool temp 1 degree every 22 minutes and the hot but one degree in less than 2 minutes.
 

funkpelts

Member
Jan 8, 2017
12
Muscatine IA
I have slowly but surely gotten the humidity figured out in our first couple of years. If I crack open a few skylights and crack open some of the casement windows down low I keep moisture under control pretty well.

- - - Updated - - -

I have slowly but surely gotten the humidity figured out in our first couple of years. If I crack open a few skylights and crack open some of the casement windows down low I keep moisture under control pretty well.

All heaters will use the sane amount of energy to heat a specific volume of water, the only difference is how fast it can do it. My MasterTemp 400 was only a few hundred dollars more than the next smaller model when we built the pool so it just made sense to go big. It’s very nice to be able to heat the spa in 20-30mins.

Have you considered using a large room dehumidifier in the winter to try to control humidity? The output would be warm dry air and condensate water. The condensate could be directed back into the pool or down a drain. Definitely would cost a pretty penny to run that but it might be better than sucking in frigid air :scratch: