Comments on: Why Do So Many Expensive Homes Get Walmart-Class HVAC Systems?

By: M. Johnson

M. Johnson — Tue, 29 Oct 2013 22:36:30 +0000

True or false: Flex duct used
True or false: Flex duct used with a good duct design, will give bad results. Hard duct used with a poor design, will give the same. What do you think and why, please.

By: Gary Bute

Gary Bute — Tue, 29 Oct 2013 21:55:41 +0000

Matt and Tim are so correct
Matt and Tim are so correct in their observations. Custom home construction demands better project documentation, products and team management. Another factor is sometimes the client driving the cost down. When told flexduct was to be used and they would save $5000 they just said "ok".

By: Tim Hart

Tim Hart — Sun, 27 Oct 2013 00:43:56 +0000

Unfortunately Home Builders,
Unfortunately Home Builders, Home, Inspectors & many HVAC “professionals” have no clue that duct design has standards, protocol and accepted practice layed down by A.C.C.A., ASHRAE, SMACNA and the International Mechanical Code as well as The International Residential Code and Energy Code. The problem is that noone is enforcing them……or trained to! Therefore there are HVAC companies who install whatever, whenever and however they feel like it and Homebuilders/ Homeowners push the price down by using them to the point that folks who do train their staff and follow codes/acceptable practices can’t compete. When will we learn that you don’t get Brooks Brothers suits at Walmart prices!! If you pay peanuts you get monkeys! And deserve them!

By: Ted Kidd

Ted Kidd — Wed, 09 Oct 2013 17:48:19 +0000

Lmao.

Lmao.

Period of silence.

Crying my eyes out.

(another nice post Allison)

By: pj

pj — Tue, 08 Oct 2013 23:03:13 +0000

Hey Allison,
Hey Allison,
I have been in meetings with Large homebuilders discussing as many as 10,000 systems at a time, sometimes negotiating over as little as sixty cents a unit, and those of us who have done this nasty business don’t talk much about what we had to do to get the order.

Once we got the job I would “cost engineer” it so we would not lose money by cutting the bed room doors up 3” to avoid returns, put the same leaky duct (“built to code”) system through unconditioned attics in each house, and watch our labor run away for 3 days if a helicopter flew over our job site.

Looking back, I can see that in building HVAC systems to the lowest cost total crap we could (anyone competing with us built) for the largest production builders, we were creating the construction jobs of yesterday and the HP jobs of today, We were thinking ahead!

I do find it silly that folks think they need to do a Full Monty, Science Project, Proctological Audit on each of the 30,000 houses in the Sub Division 10 years later, take my word for it, they don’t all Suck I didn’t do my Job right.

By: Geo Warrior AKA only 15% better eEfficiency than air to air

Geo Warrior AKA only 15% better eEfficiency than air to air — Tue, 08 Oct 2013 22:02:58 +0000
I would like a little advice
I would like a little advice on refurbishing all of the the duct work at my home.

Some review; 2,000 sqft; all ducts in attic, VAV system; 5 zones; jumper ducts to hallway return or say devoted return for any and each zone; hard pipe or metal round duct (no flex besides a couple turns), using the static regain method.

Manual D and Manual Q conflict, and it seems if any one was to install a VAV system using actual math to balance the system, they would use the static regain method. Would a designer of my creed find a plethora of information in say a certain Carrier manual or something? Can you suggest?

What sort of plenum does one suggest. There is only about ten feet upwards after the central cabinet unit coil and blower. Even so, this ten foot ends at a roof line that shares a temperature difference with the outdoors. How can I avoid turbulence? How can I avoid an octopus (with straight tentacles, mind you). (I may move the cabinet unit to the house floor and order side return unit, by suggestion of my reading the ACCA manuals -and if code allows. This would provide me a couple extra feet when installing the plenum above the cabinet unit.)

I understand many of the basics, such as increasing my return register face sqft and beveling those sides out for an inch, etc.. For example, I understand that some system effect, when all is said and done, is unavoidable. By the way, the new Manual ZR is practically no help at all for anyone employing variable speed and variable capacity equipment with VAV duct design. ZR is for bypass or over-blow designs, etc.. -Some good stuff to learn, but nothing in-depth concerning a variable capacity and an entirely variable fan CFM (not ECM) design.

What would one use for a PLENUM or first-few-feet after-a-coil-and-blower strategy for a smaller duct system that will not be using all but mathematical fudge-factors such as the modified equal friction method throughout their design? Could you wye the entire plenum in half at some point or something? (When I decrease airflow during part loads, won't many things including turbulence also change within any first plenum?)

Where is the best information on thus.

I love this band -
http://www.youtube.com/watch?v=ckQVrG91p9E

Respectfully,
The Khan of Man

By: Cameron T.

Cameron T. — Tue, 08 Oct 2013 18:09:19 +0000
[rant on]

[rant on]

Some fault for what you see above needs to rest with the HVAC contractor. If the HVAC contractor does not have the knowledge and expertise to install a decent air distribution system for a given budget, who does? Certainly not the GC, in most cases.

It has to reside somewhere. Yes, in the context above there are many competitors against paying proper attention to proper air distribution, but the question that should be asked is how much more does it really cost to do the job correctly? Does doing so absolutely kill the granite countertops and multi-sprayhead shower stall...every time? Is it always an either/or choice?

What's evident in the photos above is a never ending source of callbacks for the home builder, who will have to go after his sub (if they can be found) to find relief. Callbacks cost money...and a builder who merely resorts to ignoring the new homeowner just to save some $$ risks his reputation...unless he cranks out so many houses in a year that ticking off the buyers does not move the needle all that much. But I digress...

Bottom line: enough of this fog shrouding an obscene lack of expertise and skill. The home building as well as the HVAC industry must man up in order to realize its full potential. I am weary of the "justification" for this fog being that to do it right "costs too much". To that I say B.S. It's more apparent too much is being paid and too little is being delivered.

[/rant off]

By: M. Johnson

M. Johnson — Tue, 08 Oct 2013 17:24:44 +0000
You went through that entire
You went through that entire article and did not mention ACCA Manual D. You did mention a trunkline would be superior to 3 or more smaller ducts in parallel, it would have been enlightening to expound on the reasons why (I know some of them). It was never mentioned explicitly but between the lines I perceive you look down on flex duct. It has lower flow capacities and needs to be larger for a given air flow... but it deserves mention the problem is sizing and perhaps design, there is nothing about hard pipe which actually solves the problems you mention. Thank you.

By: James Quarello

James Quarello — Tue, 08 Oct 2013 17:13:09 +0000
People, specifically home
People, specifically home buyers, do not as a rule have a working knowledge of the mechanicals. As you state, and in my experience it is true, buyers are focused on the aesthetics. People do not show off their duct work, however they do like to show off the beautiful crown moldings and granite counter tops. The portion of the budget for the important stuff, at least in my mind, gets chiseled down to pay for the fluff.
It's hard to buck human nature.

By: Bill Hick

Bill Hick — Tue, 08 Oct 2013 16:46:14 +0000
Love it ! Seen way too many
Love it ! Seen way too many of these, in fact, I am also the proud owner of what I refer to as a "D-" system which I now use as backup to my Fujitsu heat pumps. Nothing like long runs of flex in an attic. Nice work and great photo of proud homeowner.