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Old 3/16/10, 12:25 AM
Brian A. MacNeish Brian A. MacNeish is offline
Join Date: Apr 2007
Location: CANADA
Posts: 4,587
Please Note: Brian A. MacNeish is a non-member guest and is in no way affiliated with InterNACHI or its members.
Default Re: ducting material

Originally Posted by dandersen View Post
HVAC units built in 1978 are not the same as they are today.

Also, in most cases residential air duct systems are not properly designed in the first place.

Happening in your area too!!! A very SAD!! SAD!! SAD!! state of affairs at the residential level. Home Energy magazine has reported that 20-40% of the air moving through the fan (air handler) on residential forced air duct systems does not get to or return from the intended rooms!!

I frequently recommend total air duct replacement with a new unit (as well as the disconnect box on the exterior which is often overlooked).

I don't think the HVAC guy is just trying to pad his pockets with more work.

I can document several hundred home inspections where the HVAC duct system is not functioning properly due to improper design. I advise my clients that problems with discomfort is system design not equipment performance and to not waste their money on the equipment side.

HVAC equipment can operate at full capacity and still not perform as intended.

Air stratification due to improper duct design. When conditions like this exists in new construction, you can only expect cold feet and a hot head (and not because you're pissed off)!

61F at the floor, 98F in the second-floor bedrooms (one thermostat, two floors).
If we were on top of this, every inspection department would require total heating/cooling load calculations for equipment sizing, room by room heating/cooling needs and a full duct design by certified professionals. Installers would be certified HVAC technicians and "tin bangers" would be required to seal ducts in a professional manner (high velocity duct sealer).

Last edited by Brian A. MacNeish; 3/16/10 at 12:18 PM..
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