Please clear something up

[justahomeowner]

I had an HVAC guy out last week (had to check my system due to Katrina). Anyhow I showed him the duct work in the attic and he said it's fine that all connections to the supply registers make 90 degree angles? I was under the impression that a smooth transition is generally the prefered method?

Thanks for the help

[RoBoTeq]

Generally preferred and practical are two very distinct animals. Are you having any air flow issues? The ducting must make turns.

[justahomeowner]

Yes, having some airflow problems to the back rooms. He was doing a general check as I got some water in the attic. Bascially the supply lines come off and lay on the rafters, bend up slightly and then make a 90 degree turn onto the vent.

Thanks

[RoBoTeq]

The ducting sounds normal.

[Jultzya]

Sounds normal from here.

If this is an air-flow issue and EVERY run makes the same 90 degree turn... your problem is somewhere else!

[james mo]

Since the attic should be level, I am ruling out water in the end ductwork and I am leaning towards lower blower output as a possible cause. Dirty blower wheels or blocked ductwork will cause reduced output and this wil be most noticeable at the rooms furtherst from the blower.

[dan sw fl]

Originally posted by justahomeowner
Yes, having some airflow problems to the back rooms.

He was doing a general check as I got some water in the attic.

Bascially the supply lines come off and lay on the rafters, bend up slightly and then make a 90 degree turn onto the vent.

Did his "general check" include measuring
just Two blower variables:
___ 1. the overall Air Flow ( C F M)
and 2. the External Static Pressure (E.S.P.)?

[justahomeowner]

He took NO measurements, just made sure nothing was damaged in the storm.

With my hand I can tell a difference in output at the front of the house closest to the supply trunk.

I will have him check the blower wheel, etc and go from there..

Air temp gets down to 72 with no problem. However when I walk down the hallway, I feel a temp change at the doorways of each bedroom and inside the bedroom.

This is a 1k square foot home with a 2.5 ton unit.
1 return of 16x24 and 6 supply lines

Thanks

[Black Adder]

one more reason for variable speed units with a full time fan on low. Help to even out temperatures throughout the home. System will have to be balanced as it is to acheive more uniform airflow to each room. Also if ductwork is run in the attic the further from the unit the more heat gain so it is a simple rule of nature that air furthest from the unit will be warmer. Check over the insulation on ducting and fix any leaks, then use dampers to balance the system.

[RoBoTeq]

Originally posted by justahomeowner
With my hand I can tell a difference in output at the front of the house closest to the supply trunk.


Well, you are better then any of us on this forum...we need to use instrumentation to tell air flow differences :D

I'm not trying to be a smartass, but there are many variables that can really trick your "hand" measuring data.

[dan sw fl]

Originally posted by RoBoTeq

Originally posted by justahomeowner
With my hand I can tell a difference in output at the front of the house closest to the supply trunk.


Well, you are better then any of us on this forum...we need to use instrumentation to tell air flow differences :D

I'm not trying to be a smartass, but there are many variables that can really trick your "hand" measuring data.

RoBo,

I am prettty sure that 'Justa HomeOwner' was
using his Calibrated Hand.

[RoBoTeq]

OH! Sorry...my bad :D

[dash]

Originally posted by justahomeowner
He took NO measurements, just made sure nothing was damaged in the storm.

With my hand I can tell a difference in output at the front of the house closest to the supply trunk.

I will have him check the blower wheel, etc and go from there..

Air temp gets down to 72 with no problem. However when I walk down the hallway, I feel a temp change at the doorways of each bedroom and inside the bedroom.

This is a 1k square foot home with a 2.5 ton unit.
1 return of 16x24 and 6 supply lines

Thanks


What size duct ,to the 6 supplies??6 sounds a little light,unless they are large enough.

[dirtyboy103us]

2.5 tom seems a bit large for that size house unless there's no insulation or wood frame or lots of windows 500 sq. ft per ton or if it is a Mobile home i use 400 ft is what i use here in Fla to pull out the humidity and temp

now i haven't used a ductulator for while but a 6 in duct gets you about 140 to 160 cfm that should do a 12x12 or so room. 8in 190 to 210 i think 16x14 4in 90 cfm bath rm
and at 400 cfm per ton at the air handler gives you 1000cfm these are from memory i don't do this stuff any more so give or take a little

OK is the last one on the run or the first or second thats not getting the desired pressure

if its the first or second the air is just flying by
try installing a scoop this should help

if its the last did they reduce the trunk line
are the ducts over sized in the beginning and there;s no pressure lots of things to look at

[justahomeowner]

Originally posted by dirtyboy103us
2.5 tom seems a bit large for that size house unless there's no insulation or wood frame or lots of windows 500 sq. ft per ton or if it is a Mobile home i use 400 ft is what i use here in Fla to pull out the humidity and temp

- IT'S A 50 YEAR OLD WOOD FRAME WITH LIMITED INSULATION, 8 WINDOWS IN THE WHOLE HOUSE.

now i haven't used a ductulator for while but a 6 in duct gets you about 140 to 160 cfm that should do a 12x12 or so room. 8in 190 to 210 i think 16x14 4in 90 cfm bath rm
and at 400 cfm per ton at the air handler gives you 1000cfm these are from memory i don't do this stuff any more so give or take a little

OK is the last one on the run or the first or second thats not getting the desired pressure

- LAST ONE ON THE RUN SUPPLIES BOTH WARM ROOMS.

if its the first or second the air is just flying by
try installing a scoop this should help

if its the last did they reduce the trunk line
are the ducts over sized in the beginning and there;s no pressure lots of things to look at

- INSTEAD OF WORRYING ABOUT ADDING MORE RETURN AIR, SHOULD I OPT TO INSTALL A LARGER SUPPLY FOR THE BACK ROOMS? MAYBE A 12" SPLIT TO 2 8" VS 10" TO 2 6"? BOTH ROOMS ARE 10X12 AND 12X14.

DASH -

to the warm rooms there is (1) 10" with a metal box Y and a 6" to each room. for the front rooms it's the same thing except there are 2 6" supplies.