George;

Yes, it is considered 'not a good idea' to take branch runs from the end of
the plenum unless it is an 'extended plenum of considerable length.'
Residential duct systems run at a very low static pressure and if the branch
takeoffs are directly facing the blower, there's a tendency for the pressure
to take the path of the least resistance. It's better if the branches take
from the sides so all the ducts are pressured the same. (Although sometimes
that's just not possible.)

Dampers are fine for 'small balancing' but not recommended for large
corrections. Dampers will not 'increase the pressure' in adjacent ducts,
but will reduce the air flow. It's dependent on the design of the ducts (if
it was designed at all.) ACCA Manual J is for load calculations on a
Residential / Light Commercial Building and ACCA Manual D is for designing
low pressure duct systems. You should seek a licensed HVACR contractor who
uses these guides for design work on your HVAC.

The best way to find a reputable contractor for you would be to seek
recommendations from your friends, relatives and neighbors. If they had any
'bad experiences' they'd let ya know. And please don't get more than 3 - 5
quotes. It does cost for a contractor to give a bid.

What exactly is it you want to do? Or what problem are you solving?

--
Zyp

"George Sambataro" wrote in message
...
I am having some work done on my existing HVAC system have met with 2
contractors.

One contractor has pointed out that I have several ducts at the end of my
supply plenum and that is a NO-NO. He suggest that this should be
corrected
by making the supply plenum larger and having all ducts come off of the
sides of the plenum. Another contractor is not concerned about this and
suggest that the use of manual dampers is sufficient.

How much of a NO-NO is it to put supply ducts at the end of the supply
plenum? We could use better air flow at the ends of the house and I was
wondering if the larger plenum with all ducts to the side would help.

Thanks for any advice you can provide.

George