HVAC guys in here...

[mardyn]

Trying to improve the air flow in my 3 ton system in my home. Current system has three 90* bends in two different 10'-12" duct runs...

I could replace 'em with two 45* bends and only lose a little bit of storage space in my upstairs area..

worth it or not?

yea or nay?

what say you DFWmustangs HVAC experts?

mardyn

[sc281]

Eddins Mechanical can help you out.

Reputation is well known 'round these parts.

[junk racing]

It may help a little....

[Lone Sailor]

Subscribing.

The house we're looking at seems to have low flow on the side of the house that is opposite the heat and a/c unit. There has been a small addition built on to the house at about the midway point between where the units are and the other side of the house. I'm wondering if replacing the existing main duct with a much larger duct would increase the airflow to what it once was, before the addition, or if I would need to go all the way back to where the main duct comes off the units and add a new branch off of that with new ducting and take that all the way across the attic and tie it in past where the branch ducting comes off for the small addition.

[347Mike]

Mr EDD for all your HVAC needs.

[Who Needs 8]

90 degree bends in flexible duct adds 15 feet equivalent length to the duct run. In other words, if you have a 18' run with one 90 degree turn then it will perform as a straight 33 foot run would because of the added static friction.

However, that small amount of static friction will actually only lower the cfm output by about 30 cfm at the most(the amount of air needed for a large closet). Barely noticeable.

The likely problem if you are having "flow issues" is duct leakage and or dirty blower and ducts.

[mardyn]

By the time the air flow actually gets to the end vent... probably a run of about 65 feet, it goes through about 5or 6 ninety degree turns. It still seems logical to me that by removing (lessening) the number of direction changes in the system could only improve the flow characteristics.

I can replace the first three 90* bends in the large part of the duct work with two 45s fairly easily. Cost wise, I'm not too sure...

The system works decent as is, but I just think it could be a little bit better with a few minor changes.

mardyn