Ducting:

Basic Principle: 
The dryer duct diameter exiting the dryer moves the exhaust air at a speed sufficient to drive the lint to the filter which is mounted less than 50 ft away.

Therefore we always recommend: 
Duct the dryers individually to the filter, mount, the filter as close to the dryers as is practical. The ducting to the filter must be the same size as the dryer exhaust duct.

How far from the dryers to the filter can I duct before I have problems? 
Over 50 feet of straight duct will cause backpressure sufficient to require a booster fan somewhere in the system, Remember every right angle creates backpressure equal to1approximately 15 feet of duct run.

I have too many ducts to fit the filter inlet? 
Have your sheet metal contractor fabricate a short adapter to expand the inlet to accommodate the ducts.

I am forced to duct from the dryers into a larger manifold duct, what must I do to minimize problems?
Remember, when all dryers are on and the manifold is sized for all on, then lint will be effectively driven to the filter. However, when one or more dryers turn off then the velocity of air in the manifold will not be fast enough to drive all the lint to the filter. Lint will drop to the bottom of the duct and will not become airborne even when all dryers are on.

What must I do with the lint in the manifold duct? 
There must be clean out access doors and periodically the ducts will have to manually cleaned of lint.

Manifolds and backpressure: 
Air in the manifold is moving at right angles to the air of additional dryers trying to get in. Therefore downstream dryers can dominate the exhaust of other dryers and cause backpressure. Note this problem becomes excessive when the application has large (400lb.) dryers downstream of much smaller dryers. The smaller dryer will have to be ducted directly to the filter.

How can I minimize manifold backpressure? Duct into the manifold at a “Y” angle as you would merge onto the interstate.