Pushing isntead of pulling through a CAN FILTER...anyone?

[dark horse]

Over the last couple of weeks I've been intensely learning, debating, and researching about exhaust and odor control for a micro setup.

I've just about reached the conclusion that for a small cab, a 4" blower and a CAN FILTER 33 with a 4" flange: http://canfilters.com/canfilters_33.html ... are a great combination.

In the FAQ's I read this:
Is it recommended to push or pull through the filter?
It is recommended to pull air through the filter, the reason for this is because the filters utilize the most surface area of carbon to clean the air and you use the most of the pre filter to block dirt and debris from entering your carbon pore structure. Another advantage of pulling air through the filter is that your going to have clean air running through your fan instead of air possibly laden with VOC’s, dust, and other airborne particles that could stick to the fan blades and create air resistance.




^^ That is understandable, because I realize pulling is automatically "better" that pushing through a filter. But, how much effectiveness would you really lose with this filter with it's 2.5" carbon thickness, if you put your fan/filter up in your attic, and are pushing it out instead of pulling? I am not worried about dust buildup, i will put a pre-filter over the intake inside of my cab...good idea?


Have any of you used a can filter pushing instead of pulling?

I cannot have ANY smell leaking out into my attic...am I good to go with this setup?

 

[Gr33nman]

what you read is true....that said, ive "pushed" though filters for years and as long as it is SEALED your more than fine. but you will go though fans quiker.

 

[dark horse]

K, would this be a good setup... to just sit the Can filter on the floor of the attic, and sit the fan directly of top of it so that it blows strait down into the filter?

I just don't have room IN MY CAB to pull, UNLESS i were to just exhaust my cab with a PC fan (unfiltered) and exhaust the ENTIRE closet by pulling through a filter (but my fan would still need to be in the attic due to noise).... I could do that in theory, hmmm... but then I'd have a helluva stinky closet most likely, right?

 

[Gr33nman]

go with your original thought but you will likely still hear it unless u build an insulating box. but u will have negative pressure in ur cab...good thing imo

 

[EclipseFour20]

You might consider increasing the size of your fan to compensate any "push" vs "pull" loss. I paired my Can 150 (12" flange") with a 14" fan to operate as a "scrubber" that runs 24/7--and there is no "smell issues" here and the fan is not "overworking" or straining. Look at the fan's wattage and CFM #s.

Also...may I suggest selecting a fan (does not need to be Can's) that has variable speed controls built in. It helps to "fine tune" the fan, sometimes "high" speed is too much, and "medium" will do the job with less noise and power. Not all aftermarket variable speed controllers are effective...and are known to damage fan motors.

Cheers!

 

[dark horse]

Yea but if I use an oversized fan doesn't that increase the chance of it not being as effective? Or is that where the speed controlled comes into play?

 

[EclipseFour20]

Yea but if I use an oversized fan doesn't that increase the chance of it not being as effective? Or is that where the speed controlled comes into play?

As a rule, the greater the amount of air that passes through the carbon filter--the more effective it is in reducing odors. Comparing two different sized fans that operate at the same speed (rpm)...as a rule, the larger fan will pass greater air (cfm) than a smaller fan--or put differently, the small fan will worker harder to produce the same cfms as a larger fan.

Look at the fan's wattage (power consumed) and their corresponding cfm #s. You should notice that smaller fans require more watts to do the same job as larger fans...why is that? Visualize a Prius and a Mercedes Benz both traveling at 100 mph--which engine is working harder to maintain the triple digit speed?--which engine is barely working?

The built in speed controller is a suggestion based on experience. Sometimes operating a fan at a lower speed will reduce noise, vibration, etc without sacrificing air flow and save electricity $. Why run a fan full speed requiring 400watts...when a slower speed consuming 250 or 300 watts can do the same job done...sorta like needing a "coastal breeze" and getting blown away with the force of a "hurricane".

My experience with those aftermarket speed controllers has been less than stellar and, IMHO are a waste of $$$$. Send my $1 plus postage and I will send you my $20 controller that was used one time--real cheap.

Cheers!