IAPMO Ruling on Flex Duct

I don't think this will pass as written....

"Bob Helbing, president of Air Tro, Inc. in Monrovia, Calif., added: “The air flow issues raised by IAPMO are important. But in California, they’ve already been addressed by adding a third-party airflow test to each installation. If flex isn’t properly installed, this test will discover it and force the installing contractor to remedy it. “Historically, flex ducts’ biggest flaw has been its rough interior surface, forcing fans to work harder to deliver sufficient air flow. But today’s DC and ECM motors can generate much more static pressure at much lower energy use than the older AC motors traditionally used, so this is less of a drawback today than in the past. All in all, this looks like a step backwards, rather than forwards, in terms of efficiency and delivered comfort,” Helbing added."

Bob answers this question, the installations just need to be tested to insure proper installation....I don't see this as a big problem most installs are permitted and inspected....those that skirt the rules will continue to do so...this requirement would just add to the burden on innocent law abiding contractors and sub-contractors that take pride in their work and install these systems with the knowhow and expertise that comes with years of experience....If it doesn't work you just have to come back and fix it....anybody in business doesn't want callbacks or bad reviews...I see this proposal as ill conceived and crafted by those unfamiliar with the regulatory system and standard business practices that exist today....

http://hvacheatingventilationairconditioning.com/News/IAPMO%20Ruling%20Press%20Release4.pdf

This goes back to the old problem of inspecting quality into a product/installation instead of making a foolproof quality product.

Flexible ducting is used because it is cheaper to buy and cheaper to install, as Tony said.

Bob Helbing even admits that only more powerful, efficient motors make these tubes feasible. Higher internal pressures mean more stress on a less robust system that is prone to expand and contract every time the fan starts.

Properly sized, correctly installed flexible ducting could work well, but an air flow test does not insure a quality, long lasting duct system.

So, it all comes down to the installer and how much care they take.

But, 5 feet? You may as well just outlaw its use.

There's a reasonable compromise here, somewhere. Maybe branches off the main run under xx feet?

Well any of the flex duct that I've ever seen or used has a plastic liner with a steel spring inserted that keeps the duct reasonably rounded...

....and I might add that round duct is more aerodynamic than square or rectangular steel duct that tends to make 90° turns creating a dead head situation that is noisy and creates turbulence, has no plastic liner and accumulates dust in the fiberglass inner liner if it's internally insulated....then you have the problem of sweating which creates rust and mildew....turning vanes are usually only used on large commercial ducts....Most square or rectangular duct is made from ductboard anyway in residential applications....Usually the main duct is run in ductboard anyway, it's just the drops that are run in flex....

Has anyone here heard of "dusty house" syndrome? My God, our house collects dust on everything so quickly.

I think old flex duct existing may have pinholes that under flow can induce outside flow, is that possible?

You live in Lubbock.

I've seen that west Texas dust. You couldn't keep that stuff out of a submarine.

True that. Wifey thinks that "new" cloth pleated filters (cost 10X normal 3M filter) will solve the issue. I think they will just stop up faster, and cause bypass air flow unfiltered sooner.

Sick house syndrome.

For information, go here:

www.nih.gov/research-training

Click on pubmed link.

Click on tutorial. Watch YouTube video. go back to pubmed, in search box enter: sick house syndrome.

There are 44 pages of articles / papers. You can download most for free as pdf, Adobe friendly.

Bellows effect.

I see a job opportunity here, for a local contractor.