HVAC question for fish room duct

[AuroraDave]

I want to finish the fish room area in my basement to remove heat and keep evaporation out of the rest of my house. Currently everything is unfinished, so I can run HVAC & install fans where ever I need them. The fish room is directly next to my furnace, so I can also add supply/returns if that would help.

The attached drawing shows my adjoining 10x16 Office and 10x10 fish room. My tank is currently 2’x6’, but the future will bring something wider (4 ft).

The plan is to add two intakes (one over tank and one in fish room) and exhaust thru either 4” or 6” air pipe outside. The exhaust vent will be on the top of the drawing (brown circle). The fan will be mounted in the ceiling just before, pulling the hot air outside.

I met with an HVAC guy and he provided two options. I’d like to hear some opinions on which option is better, or suggestions of changes.

Both options will run the exhaust pipe from the brown circle south over the fish tank into the fish room. That straight span is 13 feet to the tank center and another 7 feet to the fish room (20 ft total).

1) Combined â€"œ Use 6” exhaust pipe with larger 6” fan (240 cfm). Tee’d with flex to fish room from tank. I’ll have a damper on both to isolate if necessary.
$300 materials . Only one large hole/vent on back of house. Probably turn fan on when lights are on or use my temp sensor. Both would be on/off at same time.

2) Separate â€"œ Use two separate spans of 4” exhaust pipe, each with a 4” fan (110 cfm)
$225 materials. Two holes/vents on back of house. Can run each separate w/ temp sensor, timer even use bathroom fan with switch in fish room

We have discussed adding vents or even a combustion air pipe outside to offset negative pressure.

Lastly, some time ago I read posts about cutting a hole in my return to help pull moist air into furnace. Is this advisable to do in my fish room? It would be very easy since the return runs right above.

Thanks in advance.
Dave

 

[Black Mammoth]

Here are some thoughts. I don't know if they really answer your questions or not, but things to consider.

1. A 240cfm fan is more than you need for your room. Make sure that you have an opening to pull air in to your fish room. If you suck air out of the room, you'll need to draw air in to the room. Usually a door that sits 1" above the floor is enough.

2. Be careful using an intake to pull moisture out of the room. I would explain to the HVAC guy how much moisture to expect. I'm building my room now and I have an intake. However, I only plan on having it open during the winter time. It will be closed during the summer time when the humidity is up.

3. Consider putting your exhaust fan on a dehumidistat.

4. Consider using a Fantech fan

5. I'm missing why you need two outlets.

6. Consider making a hood over your tank to direct moisture up in to the fan.

 

[AuroraDave]

Thanks for the input BM, it is helpful.

<a href=showthread.php?s=&postid=14714295#post14714295 target=_blank>Originally posted</a> by Black Mammoth
Here are some thoughts. I don't know if they really answer your questions or not, but things to consider.
1. A 240cfm fan is more than you need for your room.

If 240 cfm is too large, what would be a good size fan?
The fish room is 100 SF and the tank (which will be fully enclosed) is another 32 SF.
Are you suggesting Fantech due to low sound and quality?

<a href=showthread.php?s=&postid=14714295#post14714295 target=_blank>Originally posted</a> by Black Mammoth
Make sure that you have an opening to pull air in to your fish room. If you suck air out of the room, you'll need to draw air in to the room. Usually a door that sits 1" above the floor is enough.

To draw air in the room, we've discussed 1] venting on door or wall OR 2) a 6" intake pipe to outside (but not too helpful in summer)

<a href=showthread.php?s=&postid=14714295#post14714295 target=_blank>Originally posted</a> by Black Mammoth
3. Consider putting your exhaust fan on a dehumidistat.

Good idea

<a href=showthread.php?s=&postid=14714295#post14714295 target=_blank>Originally posted</a> by Black Mammoth
5. I'm missing why you need two outlets.

That was the main question. It allows me to control the 2 areas separately and is $75 cheaper, but is that necessary??? Plus I have 2 holes on my house.
Also, I wanted to make sure 1 fan pulling air from 2 different areas would work well enough.
I am looking for opinions or experiences.

 

[Black Mammoth]

If 240 cfm is too large, what would be a good size fan?
The fish room is 100 SF and the tank (which will be fully enclosed) is another 32 SF.
Are you suggesting Fantech due to low sound and quality?


You can use a 240cfm fan if you want. I think it is more than you need, but I could be wrong. You need to calculate your cubic feet in your room. Fantech's website appears to be down, but when it comes back up there is a FAQ on their website. It shows how to calculate the right size fan. I oversized my fan for me room as well. But I wanted to make you aware of other options I went with Fantech due to suggestions on here. I installed it and I've been very impressed. It doesn't make that much noise and it appears to be of good quality.


To draw air in the room, we've discussed 1] venting on door or wall OR 2) a 6" intake pipe to outside (but not too helpful in summer)


Yeah, I only have one pipe for exhaust. I have the ability to add another one if I need to or put in an air exchanger. I suspect that a 1" gap between the door and the floor will be more than enough. Calculate the sq/inch you are venting out vs the sq/inch underneath a door (~32 or ~36 sq/inch).


That was the main question. It allows me to control the 2 areas separately and is $75 cheaper, but is that necessary??? Plus I have 2 holes on my house.
Also, I wanted to make sure 1 fan pulling air from 2 different areas would work well enough.
I am looking for opinions or experiences.

To be able to control 2 areas separately is pretty cool. It might also have an advantage as well. Money is important, but I wouldn't cheap out in this area. Your house is worth more than the extra dollars for venting. Like I said, I would be careful in how much moisture you want to pull in to your HVAC.