Ventilation Ideas

[Khazmodain]

I have too much heat/humidity in my fish room and am looking for some ideas/feedback. I have a 400g display with a 125g sump plus a 55g QT, 40g QT, and 29g QT in my fish room. This room is enclosed in an unfinished section of my basement (the 400g is an in-wall display which is viewed from the finished side).

I have been running a dehumidifier and it doesn't keep up enough and also causes the room to heat too much. Right now the fish room is about 80 degrees with 50% humidity. All of the windows throughout the house are already dealing with condensation as the outside temp has dropped.

I'm in Iowa so in the winters the outdoor temp is really cold and during the summer it gets hot and humid. I've seen some people use an air exchanger but I'm leaning more towards just an exhaust given my location. It shouldn't be too difficult for me to run a bathroom fan that vents outside. Is a 120 CFM bathroom exhaust fan adequate? The fish room is probably 25 x 20 with 10 ft ceilings (5000 CF).

Any thoughts would be appreciated.

Thanks!
Eric

 

[Dmorty217]

You would probably need more than one bathroom fan to get enough heat out. You might need to get another dehumidifier if the current one isn’t keeping up. I have 625g DT 200g sump, 125g and 75g QT and a 40g I setup for QT when needed and I have zero issues with heat and humidity is at 40%. Every situation is different though

 

[McPuff]

How old is the dehumidifier? I recently replaced mine because it was getting really sluggish. The new one is energy star and keeps humidity in check. My system is smaller at 300 gal DT with 40 gal lagoon and 60 gal sump.

 

[Khazmodain]

How old is the dehumidifier? I recently replaced mine because it was getting really sluggish. The new one is energy star and keeps humidity in check. My system is smaller at 300 gal DT with 40 gal lagoon and 60 gal sump.

Brand new dehumidifier. I upgraded to a larger capacity since my older one wasn't keeping up with the humidity. New one is making a larger impact on humidity but it is kicking off way more heat. Also have some of the heat from a 600w MH my wife uses for propagating house plants.

 

[lapin]

On my 600g with a 100 g sump I vent my room with a constant duty bathroom style exhaust fan. In summer I open the AC vent and it helps cool the room. Winter I have to close it as the heater causes the room to get hot. I am lucky that the door to my room is in the hallway as is the intake for the A/C- Heater. I am in Austin so we do have hot summers and those stupid cold fronts in the fall and winter. Spring is the problem time. Humid gulf air comes from the south and you have to change your shirts 5 times a day. Hard to keep things dry when its 100% humidity and the dew point is 75F

 

[Khazmodain]

In summer I open the AC vent and it helps cool the room. Winter I have to close it as the heater causes the room to get hot. I am lucky that the door to my room is in the hallway as is the intake for the A/C- Heater.

This is my exact same scenario. The heat (from lack of AC) in the winter combined with the dehumidifiers is causing the room to heat too much.

 

[druzzelle]

my new house is currently under construction. finally getting my fish room. the room will be finished, with a 6 inch recess in the foundation with a floor drain centered in the room and a utility sink. my 240g will be an in wall display into my dining room. I have plans for a QT, frag tank, mixing station and possible something else. the room is air conditioned, but I tried to get the builder to install a vent in the room that would be connected to a humidistat in order to control humidity in the room but they wouldnt do it, so i'll have it installed after I close. the vent I researched to install has been used by other reefers with much success so thats the route i'll go... the model is Panasonic FV-11VHL2 one of these days i'll figure out how to make uploading pics more simple lol

 

[Sisterlimonpot]

I would simply recommend an exhaust fan coupled with a humidity switch. My fish room is 732 cu ft, I bought an 80 CFM exhaust fan controlled it by a humidity switch.

The neat thing about having a hummidity switch is that the fan doesn't have to run 24/7, you can set the desired humidity and the humidistat automatically detects excess humidity and activates the ventilation fan.

Initially I set the room humidity to 30% but during the summer I would walk in there and it was too humid for my liking, so I turned it down to the lowest setting which I believe is 20% and when I walk in the room now I would notice the difference but it's not uncomfortable. At that setting I don't have to worry about mold, from my limited research, I found that 20-40% is ideal. That's a safe level to prevent mold growth and not too dry for comfort.

Here is what I documented to help determine the right size fan,

This build looks awesome!! Great attention to detail.

Your exhaust fan is 80 cfm- Is this going to be sufficient for the space (120sqft)? . I'd planned to use a 6" 400 cfm for my 88sqft room, with a plan of slowing it down to reduce noise and still get effective venting. But now I'm thinking that might be way overkill .

Also- any concerns with running all your wiring in the wall?

Again- awesome build!


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When it comes to exhaust fans it's not square feet that you concern yourself with, it's cubic feet. Although you may see a fan rated for sq ft, they're just taking into account that the common room height is 8'. My room is under the stairs and there's also a section that is only 6.5 feet tall, needless to say the ceiling heights vary, I do have the math that I used to calculate the fan size. I had to break the room up in sections to get a more accurate calculation. My total cubic feet of the room is 732 cu ft, I used this calculation to size the fan
I needed.

If your bathroom has a higher ceiling, multiply the width x length x height of the room, divide by 60 (minutes in an hour) then multiply by 8 (number of air exchanges per hour). For example, a 10′ wide by 15′ long bathroom with a 10′ ceiling would need:

10x15x10 = 1500
1500 ÷ 60 = 25
25×8 = 200 CFM rated vent fan

Using that formula, I calculated that the right size exhaust fan would be a 97.6 CFM. The standard for exhaust fans are that you typically want to exchange the room volume 8 times an hour, with an 80 CFM fan I will be exchanging the room volume 6.55 times an hour.

To answer your question, yes it's smaller than required, but not as much as you might have thought. When I sealed the tile/grout I closed the door and turned the fan on, the fan worked so well that when I was standing outside the door I couldn't smell the strong odor. I can live with 1.45 times less air exchange than what's considered the standard

Assuming that you're 88 sq ft room has 8 ft ceilings that 400 cfm will exchange your room volume 34.09 times an hour. that's a lot. based on the calculation above, your room only requires a 93.87 cfm exhaust fan. Although, I like your approach. Having the ability to set the fan speed is a good idea.

As far as running wires in the walls, I'm not too concerned, before I hung sheet rock, I verified that all connections worked by placing the apex in various locations and sending signals to devices. In the future, if something were to happen to one of these connections, I ran extra cable to all locations for future expansion and/or just in case one of those other cables fail. It definitely is a risk to put everything behind the wall but I'm hoping for the best that everything will work out and I set countermeasures on place just in case.

If I were to do it over again, I would get an exhaust fan twice the size of what was recommended. Because the more I thought about it, the 8 time air exchange recommendation was for bathrooms, and most bathrooms aren't running the showers 24/7.

To sum up, I think that if you were to calculate your room and instead of multiplying by 8 I would multiply by 16, you will be happy with just an exhaust fan and a humidity switch.