I have run into other
I have run into other problems with ductless systems. One is that all of the air is supplied from one hole on the indoor unit and returned to a hole next to it. That creates direct drafts, especially in cooling, and temperature stratification in heating. As David said, 6000 Btu/hr is too big for some bedrooms, so walk-in closets and bathrooms are pretty much out of the question in terms of cost and sizing. Another issue is that every head needs a condensate drain which can require a lot more installation headaches and maintenance problems. To me, the solution is in between. Don’t put in a 5-ton ducted system with lots of ductwork. Put in two 2.5-ton ducted systems with shorter ductwork. I am hoping that someday we will get to the point of putting in three 1.5-ton systems with even shorter ductwork. The air handlers might all be connected to one outdoor unit (or maybe not) and would be hidden in soffits or the tops of closets or the ends of closets or encapsulated in the attic or somewhere that is clever and non intrusive. The main issue is to shorten the ducts, but keep lots of supply registers and returns.

” A superior distribution
” A superior distribution system may initially cost a bit more, but the energy savings over time should make up for the extra cost.”

Correctamundo, Thomas.

Not to belabor the obvious, although that has never stopped me before, but how many installers are concerned about energy costs in a home they will likely never visit again? Present company excepted, I see little incentive for contractors to abandon a “get’er done” attitude, and until a full commissioning process becomes SOP in new construction, I despair much will change in the industry. Perhaps every crew should install HVAC (and in fact, every aspect of a home) as if they were to move their own family in upon completion. I won’t hold my breath.

Dave, I have always pushed
Dave, I have always pushed quality in everything that I endeavor to do including flexible ducting. I have yet to see a flexible duct system that “I” or anyone else has installed, that after “a few years” looks anywhere near impressive for any number of reasons. I won’t say that it cannot be done, if you can find the “contractors who build flex to impress”, but with my personal experience I have found that my rigid/flex system has provided me with a more achievable and sustainable level of quality. A superior distribution system may initially cost a bit more, but the energy savings over time should make up for the extra cost.

Much of my construction experience has centered on finding simple methods to provide a superior and sustainable building product or system. This has always centered around using the KISS principle to minimize the effort it takes for constructors to provide a consistently good (not perfect) product. With the current boom in housing after an extended slump, finding and paying for quality constructors is not an easy task, as many low skilled people are coming into the field and quality is often not one of their attributes. We all need to be open to different approaches to solving the problems presented to us and forums like this certainly provide for great learning opportunities.

I agree with all of your
I agree with all of your comments, but would like to add that the system that I describe has need for less hangers than flexible alone, as the rigid supports the flexible. The whole system only needs as much hanger support as the rigid alone would require. I believe that using two competing products (rigid & flexible) together provides for a superior system that is probably cheaper (materials & labor) than any other method of providing free-flowing insulated ducting. I have never been happy with the hanging of insulated flexible ducting alone, so I came up with my hybrid method.

Rigid ducts are sealed
Rigid ducts are sealed (possibly in sections) before putting in place. Then the flexible insulated “sock” is pulled over the duct or, if already existing, pushed back to seal the connection before the next pre-sealed rigid section. Generally, I can put the insulated flexible over the rigid in one piece. Remember a 25′ flexible duct comes in a 2-3′ box. I do tend towards overkill, so I do take care to also seal the ends of the flexible duct, but you may be right that sealing the ends of the flexible could be sufficient without sealing the rigid.

Great points, Bob. I’d rather
Great points, Bob. I’d rather see my clients use flex-done-right than 100% hard pipe given the cost difference. The problem is finding contractors who build flex to impress.

The most important criteria: use metal elbows where a gradual bend won’t suffice, fully stretching the runs, and use an ample qty of wide non-metalic support straps so as to avoid sags and pinches. In the context of a $10k+ job, the additional time required adds a small percentage to what a botched flex job would cost. It all boils down to training, defined objectives (leakage, static pressure, and hopefully air balance) and rigorous QA.

This does bring up another
This does bring up another good point to ponder between using flex duct and insulated hard duct. Most insulated hard ducting I come across has poorly sealed vapor barriers and/or the insulation is pulled way too tight to be affective. Flex duct at least only has crushed insulation at hangers and connections.

Thanks for pointing that out,

Thanks for pointing that out, Bob! That was one of my concluding points in the presentation but I had forgotten to put in the article above. I’ve added it now.

Good points, Thomas. How do

Good points, Thomas. How do you seal the duct when you pull flex over rigid? If you seal the ends of the flex well enough, that should sufficient.