ventilation question

[scott711]

With the heat arriving, I have been thinking about other ways to vent the heat/humidity from my fish room.  My fish room is in my basement.  I would like to keep my dehumidifier from going on all the time.  I was thinking about an inline fan venting outside.  Any experience or other ideas?

[ridetheducati]

With the heat arriving, I have been thinking about other ways to vent the heat/humidity from my fish room.  My fish room is in my basement.  I would like to keep my dehumidifier from going on all the time.  I was thinking about an inline fan venting outside.  Any experience or other ideas?

 

I helped a friend implement a Fantech FG series fan to manage heat and humidity.  It works really well, I believe his basement (~1000 sq ft)gets circulated 5 times per hour.  Be aware, pulling air out must be replaced with air from the other floors within the house.  The fan is outside so you do not hear anything.

[scott711]

good info.  I know about the issue about creating a negative pressure resulting in CO2 build up.  That is what I am afraid of.  I have an older house and the fish room is near the furnace.

[GraffitiSpotCorals]

I have been holding off on venting my halides through the microwave duct and outside due to me not knowing if its safe. I will have to read up on the negative pressure effects. Anyone think of anything else wrong running running my halides out the microwave duct, which goes through the wall and outside? Don't mean to high jack your thread!

[OldReefer]

I ran a 4" inline fan with a humidistat in a basement fish room. It worked really well. I would go that way again. It also gave my pH a boost since it kept the CO2 from building up around the sump.

[six-line]

I'm thinking of adding one too any brand of fan work better?

[paul b]

I installed a bathroom exhaust fan over my tank many years ago, it is also in the bsmt.  My tank is 25' from the outside wall so I ducted it outside.  I turn it on in the summer and let it run.

It does help a lot.

[Coral Hind]

I had a 3" in-line fan that pulled air out. The fan was about 12 feet away from the tank and in the laundry room so it was silent. Duct and fan were bought at Home Depot. I had mine so it came on when the MH lights came on.

[Origami]

I've been thinking about doing taking the bathroom fan approach also, Paul. I just have a brick wall to go through outside. Better to do it in cool weather than in the heat of summer, I suppose. Most of the time I've not found it necessary. I just cut a hole in a return duct in the fish room and allow the central air to mix the air with that in the rest of the house. This approach keeps the humidity in the house at a nice level which is good for a piano that we have.

 

I did recently add a fresh air intake for my skimmer. I'm fortunate enough to have a an open channel from the attic into the fish room, so I was able to run a PVC pipe from an attic vent screen to some barbs and then down some hose to the skimmer.

[Coral Hind]

Cutting a hole in the return line probably helps in the bigger picture of energy savings. A fan that exhaust to the outside means hot outside will have to enter the house which will then need to be cooled down. And that outside air may not always be much less in humidity than what you are trying to exhaust. The air conditioner will remove extra humidity as it condensates on the coil.

[Coral Hind]

I know about the issue about creating a negative pressure resulting in CO2 build up.

 

Why would a negative pressure cause a CO2 build up?

[scott711]

Is it possible to add a inline fan near a furnace?

[scott711]

Why would a negative pressure cause a CO2 build up?

because my fish room is right next to my furnace/water heater that both use natural gas.  Wouldn't it pull air from the room and if there wasn't enough "air" pull the exhaust from those two devices?

[Coral Hind]

Yes, that is true. But you are talking about CO from the gas units and not CO2 which is what we expel, that's were I was confused. All clear now.

[scott711]

Yes, that is true. But you are talking about CO from the gas units and not CO2 which is what we expel, that's were I was confused. All clear now.

So I am SOL?

[Coral Hind]

Some area building codes require there to be a fresh air intake brought into the mechanical room of the house where the gas units are located. I have a 4" line in my house just for the purpose of preventing any pressure issues. Check to make sure you don't have one.

[Coral Hind]

Do you know if your furnace pulls air in from the outside or from the in-side of the house? If from the outside you should have two PVC elbows on the side of the house normally, one pointing up (exhaust) and one pointing down (fresh air in-take). If you have this type then there is no fear of CO coming into your house unless you have a leak in the pipe.

 

If it is that close loop type furnace then you can easily add an in-line fan to the exhaust above the hot water. This will constantly pull air from the room as well as ensure the water heater vents properly.

[scott711]

Some area building codes require there to be a fresh air intake brought into the mechanical room of the house where the gas units are located. I have a 4" line in my house just for the purpose of preventing any pressure issues. Check to make sure you don't have one.

will do, I have an HVAC guy coming soon to do a checkup.  Thanks for the info.

[scott711]

I am pretty sure there is an intake upstairs and one in my stairwell.  I don't recall any outside vents aside from the gas, radon, and stove. Those are all exhausts to the outside.

[Coral Hind]

The "intake" inside the stairwell and upstairs are returns for the circulation fan on the unit and are seperate from the gas system. Just ask the HVAC tech if your furnace pulls air for the burner from the outside via a vent or from the inside of the house. If it is a newer unit it should pull from the outside as those are more efficient.

[paul b]

I've been thinking about doing taking the bathroom fan approach also, Paul. I just have a brick wall to go through outside. Better to do it in cool weather than in the heat of summer, I suppose. Most of the time I've not found it necessary. I just cut a hole in a return duct in the fish room and allow the central air to mix the air with that in the rest of the house. This approach keeps the humidity in the house at a nice level which is good for a piano that we have.

 

Tom I also had to cut through a brick wall but I also installed a whole house vacuum that needed to be vented outside also, so I just made a "Y" fitting and ducted them both through the same vent to outside.

I get to much moisture in my basement during the summer so I run it all summer.  In the winter, I need moisture so I shut it off.

[steveoutlaw]

My HVAC unit does have a fresh air supply line.  Would the mere presence of this negate the negative pressure effect if I install an exhaust to the outside?

[Coral Hind]

My HVAC unit does have a fresh air supply line.  Would the mere presence of this negate the negative pressure effect if I install an exhaust to the outside?

Yes, in regards to the gas furnace. Do you have a gas hot water heater? That could still be of concern if close to the tank exhaust. If you do have a heater and it's close just add the in-line fan to the heater exhaust and you got it covered. Because my dryer is next to my gas water heater I added a fan to my heater to ensure no pressure issues are created that would cause CO to enter the house.

[GraffitiSpotCorals]

The hydroponics store that was in manassas carried 4, 6 and 8" in line fans. I forget the brand but they looked nice. I need to research the best one, or most silent rather.

[wade]

I would be extremely careful if you have a well sealed house with drawing air outside without a true exchange (those units are $$).  Any open space - gas exhaust vents (water heater, furnace, etc) will potentially run in reverse and draw in CO, CO2, and lots of other stuff you really don't want in the house.

 

I'd second running a circulating line into the main body of the house for added humidity if you can. Your a/c will dry it out along with all the rest of the house during hot weather.