Looking for feedback & advice here.
HVAC system for high quality custom timberframe home (2900 sq. ft) to include 2 air handlers, one each for upstairs and downstairs. Ductwork to go in crawl space. The contractor wants to use all flexible duct. I like his system except for this. I’m not that impressed with the stuff and don’t want something of mediocre quality going into a house of this caliber.
What’s the deal with the flexible duct? How about insulated flexible metal duct (aluminum lined)? Would that be better?
What should I tell the contractor? Get another bid? Can anyone provide reassurance that this is a good way to go? I get the impression that flexible duct is a compromise.
Cost is always an issue but does labor intensive sheet metal offer any real advantage over the others?
Thanks
Replies
Sam,
I'm sure that you will find some usefull info in the Breaktime discussion
http://forums.taunton.com/tp-breaktime/messages/?msg=23484.3
I am currently replaceing the HVAC system in my house and have many of the same questions.
J
Sam,
"What should I tell the contractor? Get another bid? "
Tell the next contractor that flexible duct is to be limited to no more than 2 feet at connections only where necessary. Tell the one that proposed all flex, thanks, but no thanks.
"Can anyone provide reassurance that this is a good way to go? I get the impression that flexible duct is a compromise."
I can't provide any reassurance that way.
Flexible duct benefits only the contractor. It is very cheap to install. Flex allows unskilled people to install duct work, and you will pay for that initial cost savings, year after year. And frankly, contractors that would propose to use all flex, are probably not worth any further consideration, because they probably do not have the capability in house to it right. IF it is has no kinks or bends that are too tight or areas where it is crushed, it will take twice the pressure to move the same amount of air as properly sized and installed sheetmetal. It always, to some degree, has kinks, bends and gets crushed. Always. The metal flex is more expensive and less susceptable to being crushed or kinked, it is better, but not good enough. Since most residential air handlers have a limited amount of pressure available, you get a less effective system. The contractor that would install all flex will not upgrade the air handler to account for the increased system resistance.
"Cost is always an issue but does labor intensive sheet metal offer any real advantage over the others?"
First of all, sheet metal is not all that labor intensive.
Second, the benefits of sheet metal over flex are: it will not degrade, under anything close to normal circumstances, in your lifetime; lower pressure loss for the same length and flow as any type of flex; smooth inside surfaces are much less likely to catch and hold dust, and when/if necessary, are easily cleaned.