dan897857

http://m.lowes.com/mt/www.lowes.com/pd_57823-69305-7105-01-L_4294798199_4294933768_?productId=3079079&Ns=p_pr oduct_prd_lis_ord_nbr%7C0%7C%7Cp_product_quantity_ sold%7C1&pl=1&currentURL=/pl_Bath+Fans_4294798199_4294933768_?page=2&Ns=p_pr oduct_prd_lis_ord_nbr%7C0%7C%7Cp_product_quantity_ sold%7C1&facetInfo=&un_jtt_v_tabs=reviews#review_t ab

dan897857

This link is my fan by the way...100 cfm

nealtw

CMHC Garbage Bag Airflow Test | CMHC


These guys have a garbage bag test so you can prove how much air the fan can move.

dan897857

The fan seems to move air better when I took the duct off the fan so it vents in the attic. I don't want to leave it like this obviously so if I put the duct back on how can I make the fan move the air more efficiently ? ....insulate the flexible duct?

joecaption

http://www.bathroomfanexperts.com/article.php/how-to-size-a-bathroom-ventilation-fan/?id=3

Insulating the hose has nothing to do with how many CFM of air the fan can move. It's the speed and and size of the fan blades. There's nothing you can do to make it run faster or push more air. If it's sized wrong then your going to have to add another one or replace the one you have.
The insulation is to stop the moisture inside the hose from condensing and runing back into the room or laying in the hose.

nealtw

Fan to small? duct to small? duct to long? duck has to meny bends?

isola96

If the unit hold a tissue paper it's working the way it needs to nothing you can do will improve it lower it down on the steam showers.

dan897857

The duct is sized perfect to fit the hole out of the fan. The duct runs maybe 5 feet and pushed down through the soffit. It works a lot better when I took the duct off my fan. If the duct isn't obstructed the only thing I can think of is hot air naturally flows up and the cold air is restricting its movement. When the hot air is blowing down and out might the cold air be naturally blocking the warm air from moving out ?

dan897857

The duct has One end going down through the soffit. The fan is 100 cfm. Just trying to figure out why air moves better when I popped the duct off. I also have lowered the water heat down a notch.

nealtw

So the duct is 3" or 4", get an adapter to 6" and change the duct.