Exhaust Fans

[Rudder]

I went with a duct heater for fresh air in the winter.
http://www.electromn.com/gen/makeup_air.htm
This unit has 8" ducting

[TanZ2005]

Well I am glad i am not the only. My wife called me a Nerd LOL. I said I was just trying to make sure she don't have to deal with the smell coming into the living space.

James

[ryan35um]

As government keeps passing more and more smoking ban laws, these rooms are looking brilliant!

[GTCanuk]

Originally Posted by ryan35um

As government keeps passing more and more smoking ban laws, these rooms are looking brilliant!

Soon might be the only option as long they don't outlaw smoking in your own home

[papajohn67]

My smoking room is rather small (7.5X11) and when I built it I installed a Panasonic WhisperWall fan. Rated at 70 CFM but at only 1.1 sone's you can barely hear it running. It's a through the wall fan with an outside damper. Easy to install and really does a nice job.

[beamish]

Originally Posted by Da Klugs

http://www.fantech.net/inline_duct.htm

I got the 750 cfm one for my home office/smoking room. On a variable rheostat so under normal circumstances it is very quiet at a lower speed.

these work excellent I have installed numerous fans like this,I have found that metal duct works better,less restriction,also for a direct ceiling mount fan check out the panasonic whisper quiet series they are so quiet you can hardly hear them, for bath fans and such these are great.

[LEOinFL]

Question time....
I use a box fan in my mancave..turned to suck the smoke out of the room and blow it through the window.
Would closing off the window around the fan, so air can only be pulled through the fan, increase its efficentcy? I tend to think it would, but wanted another opinion before I go through the work of closing it off.
OR
Am I better off just getting an exhaust fan and instaling it?
Trying to go the least expensive/most efficent way.

LEOinFL

[ahbroody]

Man I want a man cave

[c2000]

I have a triple insulated garage that I smoke in during the winter,,I am going to purchase a Value tech fan from Farm tek (on line) its a variable speed fan that on low has a 300 cfm rating and on high has a 1,050 cfm rating. the fan is a plug in model so no fishing wires through the insulation. $179.00.. Does this sound like a good fan for my purposes..?

Jerry in Minnesota.

[Da Klugs]

Originally Posted by LEOinFL

Question time....
I use a box fan in my mancave..turned to suck the smoke out of the room and blow it through the window.
Would closing off the window around the fan, so air can only be pulled through the fan, increase its efficentcy? I tend to think it would, but wanted another opinion before I go through the work of closing it off.
OR
Am I better off just getting an exhaust fan and instaling it?
Trying to go the least expensive/most efficent way.

LEOinFL

Probably a bit of efficiency increase. The biggest benefit would be the "negative pressure issue". The make-up air would have to come from inside your home, drawing air into the room at a higher level than now given the easy access from around the fan. :Edit - Meaning that no smoke gets into any other part of the house: Pretty easy/inexpensive to build something, even cardboard type surround around the fan to seal it up when you put it in the window.

[Sancho]

I may not have built a room, or designed ductwork but I do know a few tidbits about making things quiet

Do not restrict the size of the ducting down after the blower, this is pretty logical in that you will create a high pressure zone directly after the fan before it goes to the outside. This pressure will boom back down the piping into the room, the exact frequency is based on a number of things but the primary contributors are fan speed and pipe diameter. Furthermore this buffetting air will put a load on the fan that you do not want possibly shortening the life of the unit.

Some things to think about to get the room quieter:
-Rigidly mount the duct work such that it can not shake, squeak or rattle when the unit is operating. This is especially importent for the grills that often cover the vents in the room as in many cases they are not rigid to the fan and simply clipped in place
-Avoid sizing the fan/duct such that you build a standing wave tube which be very very annoying to the occupants. (some math required)
-centrifical blowers are more efficent but louder generally when they are in their efficeny zone, to that end standard "pancake" fans are better due to the lack of ball bearings etc. consider either springing for a balanced fan (balanced all the way out of operating band, some are only balanced a few hundred hz out) or do it yourself with pennies or other small weights that can be affixed to the blades to shift resonances

Lastly, the ducting itself can be damped by using constrained layer damping material. This is basically a fancy name for tar or a substitue and an aluminium backing sheet. Science tells us this when applied to a surface puts it into double shear essentially stiffening the panel or in our case duct. This is available in the roofing ection of most home depots and lowes as temp. shingle repair sheeting its a 25' roll about 6" wide.

Always follow the rule of Pi, you will use 3 times as much as think you will need. In Daves case an acceptable fan size for four people is ~2700 cfm

[ryan35um]

What size room are you suggesting 2700 CFM for? My cigar room is 8x12 and my 1200 CFM fan is more than plenty. We have three people smoking in there often and I usually still never have the variable speed controller for the fan set to more than 1/2 or 3/4 strength. If someone were to use 2700 CFM or anything in that ballpark you'd want to be using multiple fans rather than one exit point, otherwise you'd be creating some crazy air flow patterns in the room.

Originally Posted by Sancho

]

Always follow the rule of Pi, you will use 3 times as much as think you will need. In Daves case an acceptable fan size for four people is ~2700 cfm

[Sancho]

Originally Posted by ryan35um

What size room are you suggesting 2700 CFM for? My cigar room is 8x12 and my 1200 CFM fan is more than plenty. We have three people smoking in there often and I usually still never have the variable speed controller for the fan set to more than 1/2 or 3/4 strength. If someone were to use 2700 CFM or anything in that ballpark you'd want to be using multiple fans rather than one exit point, otherwise you'd be creating some crazy air flow patterns in the room.

Im not disagreeing with you, Im merely suggesting the rule of three be followed as it allows you to massively over engineer the solution such that future upgrades are not needed. As you said, multi exit ports is going to be superior for a larger room simply because like in your room there is a noticable flow pattern and multiple fans are going to creat wicked turbulence. I also suspect that as room size increases, the required fans flow rate increases exponentially althoghu I have nothing that supports that. Merely a hunch...

[(909)]

Originally Posted by ryan35um

What size room are you suggesting 2700 CFM for? My cigar room is 8x12 and my 1200 CFM fan is more than plenty. We have three people smoking in there often and I usually still never have the variable speed controller for the fan set to more than 1/2 or 3/4 strength. If someone were to use 2700 CFM or anything in that ballpark you'd want to be using multiple fans rather than one exit point, otherwise you'd be creating some crazy air flow patterns in the room.

8'x12' floor x 8' (assumed ceiling height)= 768 cubic foot. At 1200 cfm (cubic foot per minute)you are getting 1.56 air changes per minute. That's more than plenty for a smoke filled room! One air change per minute would be minimum for a smoking area.

The only thing I am curious about is where that air is being made up. Did you open a window to let the air in? If you are exhausting 1200 cfm, you need 1200 cfm to make it up, where are you getting make up air?

[ryan35um]

Originally Posted by (909)

8'x12' floor x 8' (assumed ceiling height)= 768 cubic foot. At 1200 cfm (cubic foot per minute)you are getting 1.56 air changes per minute. That's more than plenty for a smoke filled room! One air change per minute would be minimum for a smoking area.

The only thing I am curious about is where that air is being made up. Did you open a window to let the air in? If you are exhausting 1200 cfm, you need 1200 cfm to make it up, where are you getting make up air?

Rudder and I have a similiar setup. We are getting the make up air from outside. We have ducting running from the outside of the house to the room (not a forced air setup, the exhaust fan pulls the air as needed). Assuming you live in climates that have extreme hot/cold weather you'll need a duct cooler or duct heater to make sure the air comes in at a comfortable temp.