HVAC / exhaust fan questions

[law086]

Hi folks,

I have a few simple HVAC type questions.

First - I'd like to install an exhaust fan above my equipment in my basement. When building the house, I had the builder install a 4" exahust vent. I'm looking at the Panasonic fans, some with 4" exhausts and some with 6" exhaust. My quesiton is, would I be better off with a higher output fan (150 cfm) even if I have to reduce the output from 6 to 4" or should I stick with a lower output (110 cfm) that's designed to use with a 4" vent?

Second - my house is new, just built and I have all electric utilities. So, my house heat is generated via a heat pump. I realize all the downsides of an exhuast fan without installing a HRV, but since I have a heat pump, I shouldn't worry about creating a negative pressure situation, correct? I have a daylight basement, so I'm sure freash air will get in somehow.

Thanks!
Ron

 

[jgarrison]

Keep in mind that with the increase 40 cfm it will more noisy and also I think it will be less then 40 CFM due to the restriction duct

 

[law086]

Oddly enough, the fan with the 6" output is quiter than the fan with the 4" output. .8 sones vs .6 sones.

I'm sure either would be fine as long as noise goes. But it would be good if a math wiz could figure out how much flow I'd loose from the 6" to 4" reduction.

Ron

 

[law086]

Bump!

 

[nyvp]

I just put the panisonic 150 cfm into my fish room

 

[coolkidtr]

Exhaust Fans

Exhaust Fans

Follow this link.

http://www.plantlightinghydroponics.com/index.php?cPath=76_352

I use the vortex 4 inch and 6 inch inline fans for my 600 gallon set up. They run on very low power and are extremely reliable.

Cool :smokin: :smokin:

 

[Fiziksgeek]

Re: Exhaust Fans

Re: Exhaust Fans

Are these quiet? I am also in the market for an exhaust fan for my new 210. I've had the window open so with a regular window fan, but its starting to get cold out. Can't leave the window open too much longer.!

<a href=showthread.php?s=&postid=8255548#post8255548 target=_blank>Originally posted</a> by coolkidtr
Follow this link.

http://www.plantlightinghydroponics.com/index.php?cPath=76_352

I use the vortex 4 inch and 6 inch inline fans for my 600 gallon set up. They run on very low power and are extremely reliable.

Cool :smokin: :smokin:

 

[JustOneMoreTank]

<a href=showthread.php?s=&postid=8188883#post8188883 target=_blank>Originally posted</a> by law086
Oddly enough, the fan with the 6" output is quiter than the fan with the 4" output. .8 sones vs .6 sones.

I'm sure either would be fine as long as noise goes. But it would be good if a math wiz could figure out how much flow I'd loose from the 6" to 4" reduction.

Ron

The reason that the larger fan is quieter is likely due to the fact that it can spin slower rpm and still move plenty of air compared to a smaller fan spinning really high rpm to move a similar amount of air. The faster the fan is running the more chance of it sounding like a banshee! I would go with the larger diameter fan that operates as quiet as possible that also moves the most air... compare several brands. Good luck.

 

[coolkidtr]

The vortex is pretty quiet. They are also controllable to meet the demands of your system.

Cool

 

[polaraligned]

Even if you have no furnace in your basement, a concern you
should have is the potential to draw up radon gas if the fan
is creating a negative pressure in your basement. A radon
gas test kit is available at Home Depot. IF you have a furnace
in your basement, a fan alone is a bad idea as you will create
a negative pressure and could cause carbon monoxide problem.
Unfortunatly, the times of the year that I need to vent the
humidity the most is the summer when it is VERY humid out
already. So if I have makeup air coming in it will be no better than
the air I am venting out. I think I am just going to put covers
on my tank during the humid months.

Scott

 

[law086]

I do not have a furnace, however we do have very high levels of radon in our area. I currently have a passive radon removeal system and I'm upgrading it to an active system very soon. At this point, I'm sure radon will be in check regardless of an exhaust fan install.

On a realted note, I just purchased an LG 65 pint dehimidifier from Home Depot. For all the bad rap these things get here on RC, I have to say, it is worth it's weight in gold (and it's heavy!). I love the thing. I went from 70% to 47% in a few days. I love it, I love it, I love it.

Sure, there's a bit of noise from it. Sure, it raise the temp in the room about 3-4 degrees. In my case, I have a basement sump, so none of the above is a problem. The temp in the fish room is still only 71 (ish) and my heaters are still kicking on almost constantly, even with my MH lights running in the summer. So, in thoery, the heat energy given off by the dehimidifier is also heating my tank (which is good in my case).

I'm sure I'll still get a fan, but man is this dehumidifier great.

Ron

 

[law086]

The other thing I've been wondering is why humidity increases with our tanks. Obviously you have a large body of water - but what else increases it?

In my case, I'm dropping several feet for my drain and I believe the massive amount of large bubble had a big affect on humidify levels. I recently started directing my drain into a 32g rubbermaid garbage can with the lid and I believe that's helped to reduce humidity levels.

I wonder, if you have a lot of water, but very little surface agitation, would humidify still be a big issue?

Ron

 

[Mahlhavoc]

Hello,

I did HVAC for about 15 years before I became a Honda sales rep. I can say that using cfm when it comes to output, or input for that matter, is very sketchy at it's best because it is nothing more than rule of thumb. I have seen 6" vents give well over 250 cfm and 8" vents do less than 80 cfm.

I am not sure how you are doing your venting, and a diagram would help along with living space specs and if the room is going to be sealed, but 100 cfm (ish) is not going to cause a vacuum in your house that would be something to worry about (most likely and depending on setup and total air volume) Think of it this way, a normal home with a furnace is going to eat up a bit of air with the burners, as we all know fire needs oxygen, and then it exhausts it through the roof without any ill effects, some even have power ventilation that is in the 120ish cfm range add that to a clothes dryer and an oven exhaust. . you get my point. You would see doors slamming closed with pressure buildup or notice a vacuum when opening it.

You could, depending on how you go about installing and what room size you have, install a backdraft damper directly to the outside if your room is basically sealed where you plan on placing the fan. This would allow you to exauhst air and bring fresh back in (makeup air) and that should handle your problems.

If you could give me a bit more design information I would be more than happy to give a bit more feedback and less random input.

As far as the air bubbles in your return and more humidity, yes, the higher the top water turbulance you have, the more evaporation you will inturn get and it will raise your Humidity more.

One of my tanks is a 75 Gallon and I recently removed the tank tops to allow more light and immideatly saw a large increase in evaporation, more than double the original when the tank covers were in place. So placing covers on anything that is open to the air will reduce this by quite a bit as the water evaporates it will condensate on your covers and then drip back into your overall volume of water.


I hope this is a bit of help.

Gary

 

[law086]

Hi Gary,

Thanks for the information.

My specifics: I have a 180 gallon display tank in on the 1st floor of my house in a study. I don't notice any humidity issues in that room. I have all my equipment in my basement. This includes a 100 gallon sump and 40 gallon refugium. I also have a 40 gallon quarantine tank which I'm sure adds to the humidity.

I currently do *not* have an enclosed room and my basement is fairly large (about 1600 sq feet). It's a daylight basement, so I have a large slider leading outside and four fairly large windows (the slider and windows are not near the sump).

I had the builder install one 4" exhaust duct in my equipment area and I also have a return to the air handler right above my equipment (which doesn't help this time of year when the HVAC system is turned off).

Currently, I'm running my dehumidifier and can stay under 50% humidity, which seems great. I would also like to install an exhaust fan to hook up to my 4" vent to help out the dehumidifier (cheaper to run the fan than the dehumidifier).

My house is 100% electric. So, my heat is via a heat pump.

I think that about covers it. In the future, I plan to finish the basement, move the tank down there and build a real fish room. At that time, I will seal the room, but that's a few years down the road.

As many others do, I'm trying to manage humidity without installing big dollar equipment such as an air exchanger.

I would love to hear any input you'd have.

Thanks,
Ron