Fiberglass Duct Board: The Truth Surrounding Fibrous Glass Used In HVAC

Fiberglass Duct Board: The Truth Surrounding Fibrous Glass Used In HVAC

Have you been told that duct board used for an air plenum for your HVAC system is dangerous to your health?  That flakes of insulation are falling off every day and entering the air stream that you breathe in your house?  Does Fiberglass duct board cause cancer?  How long does duct board last before I need to change it?

Boy, I’ll tell you what.  Every time I dive into a blog, I like to use my personal experience as an HVAC tech and relate it to common questions customers ask me.  But I love getting into what the real facts are.  I like to talk to people in the industry who make the product and contemplate what the EPA, ACCA, or ASHRAE has to say about it too.

The type of duct board I find in a lot of systems is similar to Mat-Faced Micro Aire Fibrous Duct Board.

Mat-Faced Micro Aire Fibrous Duct Board
Photo Credit: Johns Manville website
Johns Manville SMACNA Premium Partner
Photo Credit: Johns Manville website
Duct Board
Photo Credit: Johns Manville website
Fibrous Glass Duct Liner Standard
Photo Credit: Johns Manville website

We see duct board so much because neighborhoods built around 2000 have gone through their share of service calls.  Several of those homes have changed their AC system out completely.  But the plenums used for those systems have typically been duct board plenums.

But even if those homes had sheet metal plenums.  They’d still have fibrous duct insulation inside them?  If they didn’t, the metal plenum or distribution box would get hot in the heating season and start to sweat in the cooling season.

Guess how many parts of your HVAC system have this fibrous glass insulation as part of its construction.  At the very least, three, not one.  You have the furnace, the evaporator coil, and the air plenum.

I don’t understand why HVAC salesmen tell folks who are buying a new system that they should have a new plenum installed, specifically to prevent the use of duct board.  Are they just trying to pad the commission they get after selling you a system?  Because again, there’s no getting around it.  All manufacturers use it in their equipment.

Super-salesy type companies create “fiber phobia” in a customer’s mind, either because they heard it from their trainer or just randomly finding things on the internet to scare you into spending more money.

Here’s a sample of opinions that I’ve read from sooooo many HVAC and green energy websites:

“After the primary seal has fully deteriorated, it allows raw fiberglass fibers to be exposed to the airstream.  Turbulent airstreams wick the raw fiberglass fibers through the ventilation system, creating additional deposits within HVAC components and exposing building occupants to raw fiberglass fibers.”

Companies also show those terrible pictures of mold and dust build-up inside ducts to convince you to change your ducts or clean them.  I see mold and spores in just as many vinyl-lined ducts as I see in duct board.  If the system is regularly maintained, like something as simple as changing your air filter every 90 days, how will dirt and debris find their way into the duct system anyway?

Linacoustic RC Fiberglass Duct Liner with Reinforced Coating
Photo Credit: Johns Manville website
Linacoustic RC-HP - High Density Fiberglass Duct Liner with Reinforced Coating and Superior Acoustical Performance
Photo Credit: Johns Manville website
Linacoustic RC-HP High Density Fiberglass Duct Liner with Reinforced Coating and Superior Acoustical Performance
Photo Credit: Johns Manville website

But, let’s look at some facts:

Manufacturers like Johns Manville and Owens Corning test their products.  They use an isokinetic sampling method as well as long-duration testing.  The manufacturers rate their product for use up to 6000 ft per minute—way more than your typical residential HVAC system.

To pass the test on complying with UL-181 Section 17, the materials used in the fabrication of air ducts “shall not break away, flake off, or show evidence of delamination or continued erosion when air is passed through typical sections at a velocity of two-and-a-half times the manufacturers rated velocity.”

I found another snippet of research on the Johns Manville website: The potential for any shedding of glass fibers from the duct’s surface was evaluated at the maximum recommended velocity of 6000 fpm.  Testing was conducted using an air duct fabricated into an L shape as described in Sections 17.2-17.3 of the UL 181 procedure.

Sampling the airstream at the same air velocity as the test velocity conducted near the outlet of the duct and examined by Phase Contrast Microscopy following NIOSH Method #7400 demonstrated no detectable glass fibers in the seven-hour test.  The sampling detection limit for this test is 0.01 fiber/cc of air.

Test samples contained fewer fibers than values reported for outdoor ambient air.  Reviewing several major studies, the World Health Organization’s International Program on Chemical Safety (1988) concluded: “The contribution of fibrous-glass-lined air transmission systems to the fiber content of indoor air is insignificant.”

Complying with ASTM-C1071, the Standard Specification for Fibrous Glass Duct Lining Insulation, The following test methods have to be performed: corrosiveness; water vapor sorption; fungi resistance; temperature resistance; erosion resistance; odor emission; surface burning characteristics; apparent thermal conductivity; sound absorption coefficients; bacteria resistance; and combustion characteristics.

With duct board being so thoroughly tested, that should prove to you a few things:

  • There is no “causal association between cancer or non-malignant pulmonary disease and human exposure to glass fibers.”
  • That biosoluble glass wool fibers are thin enough that fibers disappear from the lung at the same rate as dust in the air we breathe every day.
  • That levels of respirable glass fibers in most settings are less than 1 fiber per centimeters cube,
  • And that airborne levels in insulated buildings are not significantly different than levels outside or in uninsulated buildings.

The following bodies, which are well-known industry names, can be used as references when making your assessment of whether duct board plenums are dangerous:

  • NAIMA – North American Insulation Manufacturers Association
  • ASHRAE – American Society of Heating, Refrigeration, and Air-Conditioning Engineers
  • ASTM – American Society for Testing and Materials
  • EPA – Environmental Protection Agency
  • NFPA – National Fire Protection Agency
  • SMACNA – Sheet Metal & Air Conditioning Contractors’ National Association
  • ICC – International Code Council, Inc.
  • AIA – American Institute of Architects
  • AIHA – American Industrial Hygiene Association
  • AMA – American Medical Association

Don’t Homeowners Replace Their Ducts Anyways?

Does ductwork need to be changed out at some point in the life cycle of your home?  Yes, most likely – whether it be flexible vinyl ducting or duct board.  If for no other reason than when you move into a recently purchased home.  I personally don’t want to be breathing the air, dead skin, hair, mites, and other disgusting deposits that may have made it into the ductwork from the last people who lived there.

Having provided the service myself for customers, I don’t believe duct cleaning works as well as people think.  It might knock the dust off, but it doesn’t disinfect or make it like new.

Home inspectors take a look at the exterior of ducts and determine the shape they are in by a brief glance in the attic.  But they don’t look inside them, so the ducts will pass the inspection.  But for me, as a new home buyer, I’d want to change them out.

Another reason you change out ductwork, regardless of the type of material it’s made of, is the vapor barrier surrounding the ducts.  Is it shredded or falling apart?  Does your home have hot or cold spots?  Uneven airflow?  Smashed ducts from a serviceman who needed access to the space?  These are other reasons to change or upgrade your ducting.

Photo Credit: Johns Manville website


Regardless, today I wanted to clear the air about yet another way HVAC companies send their guys out into the field with bad information.  I couldn’t find any facts why using duct board would be a poor choice or that you should change your duct board plenum because it flakes off and enters your air stream.  They were all fluff written by blog writers or companies talking about stuff they don’t REALLY know about.

My company doesn’t install duct board when we change duct systems out.  We typically use flexible ductwork.  But we do install plenums that are lined with the fiberglass we’ve discussed today.  And remember, it’s already in your new HVAC system anyways, for insulation and sound attenuation.   So, this hasn’t been a sales presentation.  I just like to know the facts, and I thought you would too.  That’s why we’ve cited specific standards made by the industry’s major players and told you their observations.

So hopefully, this has helped with any questions you have about fibrous glass duct board.

If this is your first time watching our channel, please click subscribe down below here on the right.  And if you click that little bell next to it, you’ll be notified of all of our videos as they come out.

Thanks so much for watching, and we’ll see you on the next video!

Fox Family Picnic Was a Success

The Picnic 2020

We had a great time at the company picnic at Hagan Park. The weather was perfect, and there were fun games and delicious food to enjoy. Chris Jackson, owner of Jackson Catering  came out again to do all of the cooking for us. He made tri-tip, pulled pork with little rolls, corn on the cob, mac and cheese, and his famous mashed potatoes.

We had a cornhole tournament in which Colin had to hand over the trophy from last time to Joe! He holed out his last four throws to seal the win. Everyone just seemed to have a really good time playing.

The park in Rancho Cordova is beautifully landscaped this time of year, with lots of green grass and trees providing shade from the sun. Sasha and Jassmine reserved the main pavilion and set it up for us to take refuge in if we needed a break from the heat. Overall, it was such a fun day spent with my colleagues, and I’m so glad that we could spend some time outside together enjoying all that the park had to offer.

Whether throwing the football around, tossing the baseball back and forth, or playing badminton, there was something fun for everyone to do at our company picnic. And, of course, no outdoor event would be complete without some tunes, so there was Greg’s handpicked playlist blasting throughout the afternoon as well. Thanks for a great day, Hagan Park! We can’t wait to come back next year.

Fox Family Picnic 2022

How Much Money Do HVAC Workers Make an Hour? (2022 Update)

How Much Money Do HVAC Workers Make Per Hour
How Much Money Do HVAC Workers Make Per Hour

The HVAC industry is one of those jobs where going to college isn’t required. You can make a huge impact on people’s lives RIGHT NOW. When people don’t have heating, cooling, or refrigeration, you fix it. You see the results right now, you feel good, and you move on about your day. How much money do HVAC workers make to do that? We’ll talk about it in this video.

Hourly Rates for HVAC Technicians

HVAC techs make good money. You’re not likely to start out at minimum wage, but it’s possible.

Knowing this, you can expect the average salary for an HVAC to be from $20.00/hr (about $40,000/yr) to $50.00/hr (about $90,000/yr). The average technician makes $25.00/hr.

  • Alaska has the highest average pay rate at about $40.00/hr. Alabama has the lowest right now, with an average salary of $19.00/hr.
  • California has the most HVAC jobs available, paying over $50,000 a year. Alaska has the lowest percentage of HVAC jobs offering more than $50,000 a year.
  • Connecticut, Maryland, California, Massachusetts, New Jersey, Pennsylvania, Vermont, New Hampshire, Florida, Alaska, and New York all have at least one city where the average technician makes $40.00 to $50.00/hr.

Types of Jobs Within the HVAC Industry

In the HVAC industry, most people think about positions like installers, repair techs, and preventive maintenance techs. And those positions can be held in the residential field (homes), commercial (stores, offices), industrial (hospitals, high rise buildings), and refrigeration (grocery store frozen and fresh food items).

Each one of those types is going to make different money. Residential techs typically earn a little less than commercial and refrigeration techs, which usually make slightly less than industrial techs. You’ll also find that many commercial, refrigeration, and industrial jobs are typically associated with union jobs.

There are more than technician jobs in HVAC too. We need warehouse workers, truck drivers, front desk workers, administrative assistants and dispatchers, “Title 24 HERS” raters, “Home Performance” salespeople, HVAC equipment salespeople, sheet metal fabricators, pipefitters, department managers, territory managers, equipment manufacturers, parts manufacturers, air conditioning engineers, and system engineers.

So there are several jobs available within the HVAC industry. You find a lot of people who finish up their time in the field switching over to some of these less intense, physically demanding positions. Even HVAC business owners who retire from running their company will seek those jobs as a nice supplemental income to their retirement or just stay in the field and have something to do!

I hope this helps with the HVAC salary question.

What’s the Required Service Area for HVAC Installations?

Installing Equipment Safely and to Code for our Sacramento Customers

When we install HVAC equipment in people’s homes, there is a code that covers how much service area there needs to be in front of the equipment.  That’s what we are talking about today on Code Corner.  Let’s take a look at what the codes say and adhering to to the code when doing an HVAC change-out.


I’m not here to pretend I know or could even interpret all the codes correctly.  I’m simply trying to open a conversation about codes we cite on the job every day out there without even knowing it.

But where is that code in the book?  That’s what this project is all about.  Ultimately, this project is good information for technicians but if they help you, then that’s great!  And good for you for even caring about the building codes enough to read this blog post.  It means you care about your work too!

Let’s take a look at what the codes say about Required Service Area in front of the HVAC equipment and adherence to the code when doing an HVAC change-out.

Making Space

Have you ever been in front of a furnace in the attic, and noticed you don’t have enough space to work?  Imagine you need to pull the heat exchanger from the furnace and change it with a new one.  If there’s not enough room in front of that furnace, the technician won’t be able to remove and replace parts as needed.   And trust me, this accessibility issue is a major problem because if we can’t get that blower motor out, a more invasive procedure needs to be carried out to extract the part which will cost the homeowner more money at that time in the future.

This has already happened to people a long, long time ago, and they learned from it; And they wrote it in a book so that future techs won’t make the same mistakes they did.

Now, imagine you’re trying to perform a regular maintenance, but can’t get the access panel off the AC because a giant lattice structure has been solidly built around it.  The homeowner doesn’t want to LOOK at this horrid AC in the back yard, so they cover it up.

Well, the builder of the lattice structure at the AC, and the installer of the platform or non-existent platform at the air handler in the attic didn’t install this system properly.

CMC 304.4.3 says a level working platform not less than 30 inches by 30 inches has to be provided in front of the service side of the appliance.

IMC 306.1 says the same thing

The exception to this rule is that a working platform doesn’t need to be provided when the furnace is capable of being serviced from the required access opening. In this case, that furnace can’t be over 12” from the attic access either because some techs might not be able to reach components inside the furnace casing.

Now, you know I like to encourage you to read the installation manual while you’re installing the equipment, right?  I personally like to look through it the night before my next install.  That way I know what I’m saying if something comes up during the install with my co-workers.  Usually, the manual has more restrictive guidelines when installing HVAC equipment.  The city and county code inspectors everywhere defer to the installation manual so many times because the manufacturer has stricter requirements for the installation.

Referring to the Mechanical Code

In the IMC, in 102.1 Conflicts in Code, it says if the codebook and the installation manual conflict with each other, to follow the more stringent requirement.

The installation manual for our equipment in the attic says the clearance in front of the furnace and coil in the attic is required to be at least 24 inches.  If the county inspector adheres to the IMC or CMC, and it says 30 inches in front of the appliance, but the installation manual says we can go 24 inches in front of the unit.  Which is the correct answer?

In this instance, the mechanical code is still more stringent on its requirements, so when I hear people say we only need 24” in front of the furnace, I know it will probably fly, but the inspector could call us on it and ask for a 30” service area in front of the unit.  And you need to know that.

The service platform is supposed to be constructed from “solid flooring.”  Many techs around here use 5/8” plywood. I wouldn’t use 3/8” or 1/2” plywood, because it’s pretty flimsy for bigger guys, and over time can splinter and break.  Nobody likes to sit on a flimsy service platform that was supposed to be built “solidly.”  Instead, get the 5/8” thick plywood.  Its only a few more dollars and will be secure for any technician who has to crawl across it.

Avoiding Obstructions and Providing Space

Is it okay if the service platform is uneven?  Like a step up or down?  I don’t think anybody will give you a hard time if the decking for the service area is 4 inches higher at one point than the other.  The point is to be able to pull parts from the unit without any obstructions, like a wall or truss, and have a spot to put your tools and anything else you might need for the job.  So if that step is going to interfere with the changing of any part of that system, it’s not built to code.

Outside at the AC, just make sure you have a 30 x 30-inch area in front of your access panel.  This ensures future techs can get in there and make the necessary repairs to get the customer up and going again.

Consider the Next Installer

If your homeowner is going to build that lattice structure around the AC, ask them to build it so it can be slid out and then back when the AC tech moves on.  Don’t let them pour concrete piles so it’s secure but never going to move again.  That inhibits technicians from doing their job safely.  There’s nothing more frustrating than having to take down the lattice panels around an AC one screw at a time, just so you can get in there and clean the AC so it will work properly again.

As installers, I believe we have a responsibility a to consider the next tech who comes to service this equipment.  He or she might not be 5 foot 8, and 165 lbs.  There are short techs and tall techs, narrow techs and wide techs.

Correct Equipment Installation

That’s what this series is about.  It’s not to say that I know all the codes, and can interpret them perfectly.  Code Corner is about Fox Family Heating and Air wanting to install equipment correctly, so we can pass the inspection that comes with pulling a permit for the job.  Read more about HVAC installations here.

Remember, any time we alter the electrical, mechanical, plumbing and gas lines, we need to pull a permit and follow the codes and the installation manual.  And then we need to have a third party, unattached inspector come by, and just make sure we installed it correctly.  It’s not a bad thing!  We just look at it as an extra set of eyes on our work to make sure the family who resides in that house, and uses that system we installed, is safe forevermore!

Looking Ahead

I have several other topics I want to open a conversation about when it comes to HVAC and the building codes.  I really hope nobody is taking offense on these topics.  My goal is to elevate the HVAC world and make us all better technicians so we can go out and take care of our customers safely.

Comment below if you’ve have had any weird platforms or service areas so tight you couldn’t service the AC!  I’m sure you all have some great stories.

Thanks so much for watching and we’ll see you at the next blog.

Why Attic Insulation is Important in Your Sacramento Home

Why Attic Insulation is Important in Your Sacramento Home

You may not need to look further than your attic in case you suspect that your home is no longer as energy-efficient as you want it to be. The insulation of your attic may have deteriorated. This article discusses some of the compelling reasons why you should have the attic of your Sacramento home insulated this summer.

Keeping Cool Air In

Warm air has a tendency to rise or flow to places that are cooler. In this case, the warm air outside your home will try to find its way inside through the attic and other gaps in the exterior envelop of your house.
Such heated air will end up displacing the cool air within the home if the attic isn’t properly insulated to prevent such air movements.

Proper insulation serves the role of blocking heated air from outside from getting in. Consequently, your Sacramento home will stay cool during the summer heat.

Keeping Interior Temperatures Stable

Another key reason why you should insulate the attic of your Sacramento home is the effect of such insulation upon the regulation of the temperature inside the home. Homes with poor attic insulation are likely to have hot and cold spots due to the leakage of conditioned air through the attic.

The cool air provided by your air conditioning system can keep escaping to the attic as warm air from outside gets in. This entry of warm air ends up causing the affected sections of the home to have fluctuating temperatures even if the AC is working as it should. Adequate insulation in the attic averts such temperature differences.

Reduced Energy Bills

As you may have already noticed, proper attic insulation has a beneficial impact upon the energy needed to keep your Sacramento home cool during the summer. This benefit comes about because less energy will be lost in trying to make up for the conditioned air which has escaped through the attic. The air conditioning system will, therefore, find it easier to maintain the temperature which you have set for the home.

HVAC System Longevity

The lifespan of your Sacramento HVAC system will also benefit from attic insulation. This is because the unit will not run for extended durations in a vain attempt to keep the home within the temperature range that you have selected.
The shorter run times (and longer intervals before the system cycles on again) will cause less wear and tear. Expensive repairs come when different components of your air conditioning system are overworked. Consequently, the system components will last longer than the AC components in another home whose attic isn’t properly insulated in the summer.

Better Indoor Air Quality

Many homeowners in Sacramento complain of unpleasant odors within the home. People who suffer from allergies may also experience frequent flare-ups in homes where the attic isn’t adequately insulated. Such problems may arise because condensation or moisture may accumulate within the attic due to the frequent temperature variations that take place at different times of the day or year. That moisture promotes the growth of mold, mildew, and rot.

The filters of your AC system may also end up getting clogged quickly due to the heavy load of pollutants which must be removed as the air is recirculated within the home. Attic insulation can go a long way towards preventing mold and other pollutants from compromising the air that you breathe inside the home.

Attic insulation is available in different forms, such as foam insulation and batt rolls. Talk to an HVAC repair professional in Sacramento so that he or she can help you to select the most appropriate attic insulation in order to make your HVAC system more energy-efficient.