What is “The Science of Air-Flow”, & How Does it Benefit Me?

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flow hood

Actually, the term, “Science of Air-Flow” is one created by Bird Family Insulation to describe our protocol of testing & measuring the efficiency of residential HVAC duct systems. After many years in this business of fixing home comfort challenges for homeowners (since 1998), and having been in many 1000’s of GA homes, President Bob Bird has determined that the average home has major duct issues.

And these issues are commonplace! We see them in million-dollar+ homes, new homes, remodeled homes … everywhere!

The First Time ….

Bob first began noticing the problem in the early years of the business. One such appointment he has never forgotten. He was called out to diagnose why the bedroom floor in a house (beautiful, custom, million $ brick multi-level home) was not comfortable, even-though the attic had 16” of fiberglass insulation, and had plenty of HVAC capacity for cooling. Standing in that massive attic, He began asking God to show him, “Why aren’t these rooms cooling down?” The answer became clear: the ducts were suspended in the hottest part of the house, like laundry on a clothesline in the highest elevations of the attic! That region of the attic regularly hits 140 degrees! Bob redesigned the ducts to lie on the attic floor, and buried them beneath a thick layer of cellulose insulation. The homeowner’s family was ecstatic with the results …. “Our son doesn’t wake from his afternoon naps with his clothes soaked from sweat anymore!”

It’s just common sense, right? Not so quick! In 2006 Bob was included in an innovative “Home Performance” training endorsed by a local utility and taught by a nationally-recognized and awarded team of trainers. The room was full of HVAC contractors, and Bob was the only insulation contractor for the week of training. During class discussion, he mentioned his technique of dropping & burying ducts – and his idea was giggled at and minimized. We kept doing it anyway; homeowners were loving our results! In 2016, Bob’s technique was recognized in an industry publication as an acceptable way of “bringing the ducts inside the envelope”.

Why is this story important? Because it shows again and again that Bird Family Insulation is motivated as a Solution-Driven Contractor, vs being a Product-Driven Contractor.

Our passion is solving your Comfort and Air Quality issues. We sell value, not products.

Providing Value

Being 100% convinced that he was onto a major revelation as to why some homes didn’t dramatically respond simply to “more attic insulation”, Bob began reading, studying, and talking to others in his quest to understand residential HVAC.

  • In 2010 he sent Beau Bird to Seattle, WA for a two week lab/class on gas furnaces.
  • Bob has taken several classes on duct design, load calculating, etc.
  • In December 2017, Chris Bird will graduate from a local Technical College with a degree in HVAC, and later join the company with a brand-new HVAC division for our clients!
  • Our sales staff has introductory training with Flowhood, and other diagnostic tools, using them regularly to inform homeowners of the issues and problems with their ducts.

We share this story, in such detail, so you appreciate the benefit you receive from employing the Bird Family team! You have access to this wealth of experience, training, and knowledge. We are motivated to learn, so you win! You don’t have to suffer with hot or cold zones in your house, or poor indoor air quality inside your home.

Common Duct & Airflow Issues We See Everyday in Homes

(not exhaustive list by any means).

  1. High-performance equipment attached to inefficient, 50+ year old duct systems. You should be getting (as close to) 400 cfm airflow per ton of AC.
  2. Leaky ducts. The U.S. Gov’t states that the average American home is losing 30% of conditioned airflow from leaky ducts. For every 3-ton system, that’s ONE ton of airflow never reaching your living space!
  3. Poorly designed duct systems. Small diameter ducts stretched waaay too far. Badly-configured connections. Wrong size duct for the “load” required by the room.
  4. Not enough Return Vents, nor Return Airflow! This is a huge universal problem.
  5. Sloppy duct design. We’ve cut out 10’ of excess duct in many cases, PER VENT!
  6. Out-of-Balance Airflow. When comparing your Supply-side airflow to the Return-side airflow, the total airflow (measured in cfm, cubic feet per minute) of ea “side” of your system should be within 10% of each other. It’s very uncommon to see a balanced residential system!
  7. Wrong vent “grill” design for the application. Those nice wood floor grills are dramatically restricting your airflow!
  8. Rodent-Damaged ducts, Crushed ducts. Torn & Disconnected ducts.
  9. Plenums falling off the airhandler, Boots not matched to the hole cut through the ceiling or floor, Filter-trays with no covers, collars pulled out of duct-board, etc.
  10. Ducts suspended right under the roof deck, in the attic. Ducts lying on the ground in crawlspaces.
  11. “Zebra-stripe” flex ducts… meaning the duct is holding water.

Airflow & Duct System Trivia

  1. “In [our region], a fixed 3-ton, ducted AC system will cycle on-and-off typically 3 to 5 times an hour.” Debbie Sniderman, Home Energy Magazine, March/April 2014.
  2. “The cooling industry in the southeast U.S. was built on immensely oversized high-profit outdoor systems that needed servicing often.” Debbie Sniderman, Home Energy Magazine, March/April 2014.
  3. If more airflow is needed, larger (bigger diameter) ducts are necessary.
  4. Our testing commonly reveals that units in older homes are moving only 60-65% of the airflow they are capable of moving.
  5. Undersized ducts are the second-most common issue we find in duct systems of older homes. Not enough Return vents is the most common issue we discover.
  6. Older homes with ducts located in a vented attic typically lose about 30% of their heating and cooling ability through leaky, poorly insulated, and poorly designed duct systems.
  7. Said another way, your new 3-ton, 14 SEER AC, located in your vented attic, attached to those older ducts, is most likely performing at 11 SEER energy efficiency and providing you with  ~ 2 tons of airflow! That’s WHY some HVAC sales people push to sell you a larger 3.5 ton system… to compensate for the obvious losses.
  8. The more efficient duct design is a central trunk line extending through the center of the house, with flex ducts (branches) providing smooth, straight runs to the rooms.
  9. If replacing an HVAC unit is not an emergency, first test the ducts for leakage & airflow. Seal and insulate your ducts as part of the equipment replacement. Be sure to test-out after the work is completed!
  10. Proper airflow for ducted, forced-air systems is 400 cfm / ton of AC. A 3-ton system is capable of 1200 cfm.
  11. After sealing some duct systems, we have actually seen airflow reduced! This occurs when there is excessive duct leakage, and after the holes are sealed, the air is forced to move through the restrictive duct system. In extreme cases, equipment may short-cycle until airflow is increased.

Common Upgrades made by the Bird Family

A combination of the following upgrades are common tasks that benefit our clients with dramatically improved comfort levels in their homes. (Not exhaustive list).

  • Add larger ducts.
  • Add dedicated Supply ducts and vents.
  • Add Return vents, with dedicated ducts.
  • If ducts are hardpipe (sheet-metal), we Seal & Insulate ducts, using Closed Cell Spray Foam.
  • If your duct system is flex duct, we use a combination of mastic and spray foam to seal the connections, boots, etc..
  • Sometimes, it’s best to replace entire duct system, and redesign at the same time.
  • Upgrade grills to low-restriction units.
  • Install Whole-House dehumidifier system, plumbed into the ducts. (When your house feels stuffy, humid).
  • Use Spray Foam Insulation to seal and encapsulate the attic or crawlspace.
  • Drill & Fill existing wall or ceiling/floor systems, garage ceilings and walls, using cellulose insulation.

Are you ready for an enthusiastic experience? After all, it’s your home – Shouldn’t you be comfortable?

Ready for an Instant, Online Estimate? Simply go to https://birdinsulation.com/hvac-estimate/

Have a Question? Contact Savannah Bird in our office, at 404-538-9168, or reach us at Bob@Birdinsulation.com

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