When is a duct booster fan OK?

[dash]

Low static pressure in the duct permits the air to travel easier in the duct. Since the pressure is lower, it doesn't force out more air then required to the closet supplies.

High static pressure causes the closet supplies to get more air then the rooms need.

Exactly!

Booster fan ,when ducts can't be corrected due to construction.


Improving ducts in an accessable basement ,could lower the static enough to mean that the ducts in the walls are "now" large enough.

Lowering static close to the indoor unit ,makes more available for the farthest runs.

[captube]

Good one Beenthere
Lightbulb came on when i read this, thanks!

Low static pressure in the duct permits the air to travel easier in the duct. Since the pressure is lower, it doesn't force out more air then required to the closet supplies.

High static pressure causes the closet supplies to get more air then the rooms need.

[beenthere]

Improving ducts in an accessable basement ,could lower the static enough to mean that the ducts in the walls are "now" large enough.

I didn't want to imply to anyone that may be a DIYer, that automatically the ducts in the wall will be large enough.

EG: A 7" oval running 8' vertical, and 14' horizontal to the master bedroom that should have 200 CFM.

[beenthere]

Good one Beenthere
Lightbulb came on when i read this, thanks!

Its one of the harder things to explain to a customer when you tell them the room that didn't cool well before, will now. When they say, "but you said it won't blow as much air in low".

[Joe Mascitti]

How much will the booster fan raise the temp of the air coming out of the supply?


Joe

[beenthere]

How many watts is the motor. 3.413xwatt=btu

[Bushum]

These little fans can kick it out!, but you must realise that they are stealing air from someplace else.

Wouldn't this also be true if the ductwork was sized correctly in the first place? A system only makes a max amount of airflow that is distributed right?

[Joe Mascitti]

Use 241 and 137....that would equal 822BTU and 468 BTU


How does that equate to temp


Thanks


Joe

[Joe Mascitti]

"Wouldn't this also be true if the ductwork was sized correctly in the first place? A system only makes a max amount of airflow that is distributed right"

Does the booster fan increase CFM above the system design?


Joe

[beenthere]

temp rise =BTU/(CFM*1.08(at sea leel))

[pstu]

I install Fantec stuff. Correcting the duct work would be great, but sometimes you run into a lengthy branch that has minimal static pressure and virtually no throw.
So I install a 6 in in-line booster fan with a variable speed controller that's wired to come on with the indoor blower. These little fans can kick it out!, but you must realise that they are stealing air from someplace else.

If the power were off to such a fan, the added restriction of the fan itself would greatly reduce airflow, right? Just trying to learn what is what. It seems to me that power to the fan would be necessary in order to get anything like the original airflow. But as has been shown before, sometimes my impression can be dead wrong<g>.

Thank you -- Pstu