Testing HVAC Ductwork For Air Leaks-1 

Part-1 Of Our Multi-Part Article Describes 75+ Ways To Lower Cooling Costs

Without Replacing Your HVAC System

(Most Of These Ways Also Lower Heating Bills)


NOTE: Most Of These Efforts Also Lower Lower Heating Bills. 

Part-1 Details Testing HVAC Ductwork For Air Leaks — As Part Of Our Multi-Part Article Describing  75+ Ways To Lower Cooling Bills Without Replacing Your HVAC System.  Al’s Plumbing, in Plano, Texas Provides Full-Service Plumbing; Maintenance, Repairs, and Replacements For Every Plumbing Component In Your Home. 

Call Al’s Today To Discuss Any Concerns Or Problems You Have With Your Home’s Plumbing. 

We will arrange an appointment at your convenience.

What’s Discussed In Part-1:

THE 4 Easiest Ways — To Lower Cooling Bills (& heating bills)

  • A. Finding The Lowest Priced Electricity Retailer (For Texas only).
  • 1. Install Automatic Smart or Programmable Thermostat.
  • 2. Testing HVAC Ductwork For Leaks. 

  • 3. Sealing Ductwork Air Leaks.

What’s Discussed In Part-2:

Ductwork Sealing – Continued:

  • 4. Ductwork Sealing Products — Durability Test Results.
  • 5. Aerosol Ductwork Sealing (for existing homes) — seals from inside the ductwork.
  • 6. Typical Home Air Leakage — Shown By Decade The Home Was Built

What’s Discussed In Part-3:

  •   7. Where Homes Leak (the most) Air  — And How To Close The Holes To Lower Lower Cooling Expenses.  NOTE: Continued in Part-4.
  • PLUS The products needed to seal the most common leaks are shown.

What’s Discussed In Part-4:

  Where Homes Leak (the most) Air — Continued. 

  • Exterior Doors
  • Pocket Doors (slide into the wall)
  • Windows
  • Electrical Outlets & Switches.
  • PLUS: The Products Needed To Seal The Most Common Air Leaks.

What’s Discussed In Part-5:

  • Home Resident’s Actions That Contribute To Air Leakage.  

What’s Discussed In Part-6:

  • Home Air Leakage & (Texas) Insulation Levels Over The Years. 

What’s Discussed In Part-7:

  • HVAC System Maintenance

What’s Discussed In Part-8:

  • Energy Saving Habits That Lower Cooling Costs

What’s Discussed In Part-9:

  • Energy Saving Opportunites That Lower Cooling & Heating Costs 


large home

Image Source:

The 3 Easiest Ways To Lower Cooling & Heating Bills

Finding The Lowest Priced Electricity Retailer — (Texas Only)

To Skip This Section — Scroll Down To The Next Double Lines.

Dallas-Ft. Worth (DFW) is served by 1 Electricity Distributor — ONCOR.

DFW Is Served By Many Electricity Retailers.

Retailers Buy Electricity At Wholesale Prices — Then Sell It At Retail Prices.

electricity distribution lines with transformers

Image Source: Shutterstock

In Texas — Cooling & Heating Costs Represent 41% Of Residential Energy Bills

According to the U.S. Energy Information Agency:

  • Texas Cooling & Heating Costs = 41% of total residential energy bills.
  • Texas cooling costs = 19%.
  • Texas heating costs = 22%.
  • The reason heating costs exceed cooling costs — is because nearly 2/3 of Texas homes have electric heat.

According to the U.S. Census Bureau: *4

  • 61% of Texas homes have electric heating.
  • 35% have Natural Gas heating.

Natural Gas powers 55%–75% of Texas electricity generation (actual % depends on wind conditions).

Wind (22%), Coal (13%), & Nuclear (10%) provide the rest of Texas’s electricity.

March 2021 Texas Electricity Prices For; 2,000 kWh (Rate) — in Oncor’s (DFW’s) Service Area ***

  • Low:    8.5 cents ***
  • Retailer: First Choice Power
    Plan: You Got This 12-fixed
  • High: 12.1 cents ***
  • Retailer: Ambient Energy
  • Plan: Lone Star Classic 12

Using The Resource Shown Below *** — You May Be Able To Lower Your Total Electric Bill

By 1/4 Or More By Simply Changing Your Electricity Retailer.

*** Source:    PUC Stands For: “Public Utility Commission”.

End Of Section: Finding The Lowest Priced Electricity Retailer (Texas only).

1970's built home

Image Source: Shutterstock

Homes Built Before 1980 — May Leak Up To 4 Times As Much Air As Homes Built Since 2010

1. The Top 4 Things To Do — To Lower Cooling Bills (& Heating Bills) 

  • Automatic Setback OR Smart ThermostatIF your home is not always kept at the same temperature 24/7.
  • These thermostats can reduce cooling/heating demand — while you’re at work, or at night while sleeping.
  • Then it resets to the temperature you want — at the time you want it.

Image Source: Embedded Link 

SHOWN: 2 Adjustments / Day Programmable Thermostat

Click On Image To; View Product, Read Details, or Purchase From

Programmable/Smart Thermostats are inexpensive and easy to install.   They adjust your home’s temperature cooler or warmer at the times you choose.  You program the thermostat to automatically set the temperature at the times you want.  Once programmed — the thermostat needs no further attention.

Smart Thermostats Can Lower Cooling Costs (& heating costs)   

If Your Home Has Electric Heat — Heating Costs Savings Are Even Higher. 

Image Source: Embedded Link 

SHOWN: Google-Nest Smart Thermostat In Dark Gray (other colors available)

NOTE Most Smart-Thermostat Brands Have Identical Features.

Click On Image To; View Product, Read Details, or Purchase From


The Google-Nest Smart Thermostat’s Buyer Satisfaction Rating Score = 4.5 Stars (out of 5) — with over 30,000 buyer reviews on Amazon alone.


Click Here To Learn More About The Google-Nest Thermostat: Google-Nest Smart Thermostat


A Smart Thermostat (such as Google-Nest) Can Do These Things — That Programmable Thermostats Can’t Do:

  • Nest learns & remembers your cooling & heating preferences
  • Nest Programs Itself — by tracking what temperature adjustments you make for a few days.
  • You can also program it.
  • Nest learns how long it takes for your HVAC System to restore the home’s temperature.
  • Each day, Nest goes online to get the outdoor temperature.
  • It starts cooling/heating only soon enough to reach your desired temperature at the time you want it.
  • This feature saves more energy than a programmable thermostat.
  • As compared, a Setback Thermostat adjusts the temperature when you told it to — regardless of outdoor temp.
  • This can lead to increased energy usage during mild weather — OR a house that’s too cool during cold winter weather.
  • In summer — Nest can sense and help reduce indoor humidity levels (using the A/C).
  • You can adjust Google-Nest through its APP and/or Amazon Alexa.     Note: This feature is also available on some programmable thermostats.
  • Nest can notify your cell phone if the home’s temp gets too high or too low — indicating a possible shutdown of the HVAC system.
  • This is a valuable feature in the northern U.S. — where a furnace breakdown can lead to frozen water pipes.

2. Testing HVAC System Ductwork For Air Leaks

 (Typically Includes As Part Of Ductwork Sealing Service)

In 2009, the International Energy Conservation Code (IECC) began requiring Testing HVAC Ductwork For Air Leaks.

NOTE: Most states base their Building Codes on IECC — but some states adopt the latest IECC codes (IECC updated every 3 years) later than the year IECC added the codes.

Steps In Testing HVAC Ductwork For Air Leaks:

  • All air-return grilles & supply-air vents are sealed off.
  • 1 return air grill is connected to the testing fan.
  1. The testing fan pressurizes the ductwork system — and creates the same air pressure as a furnace blower.
  2. Once The Ductwork Is Pressurized, a device measures how much air — continues to flow through the fan.
  3. Measurement (from #2) — is how much air is leaking from the ductwork.
  4. The leakage result is often represented as a fraction.  Example: 4% ductwork air leakage.

NOTE:  If There Were No Ductwork Leaks — There Would No Air Going Through The Fan (once ductwork is pressurized).

Image Source: YouTube Embedded Video

To View Video — Click On White Arrow In The Center Of The Image Above

3. Sealing Leaking Ductwork (In Homes Built Before 2012) — As Needed

Typically Testing HVAC Ductwork For Leakage — Is Done Before A Ductwork Sealing Effort.

Before You Choose A Contractor To Perform Testing HVAC Ductwork Air Leakage — Ask If They Test It First.

Up To 1/3 Of Cooled/Heated Air May Be Leaking From Ductwork

ductwork for hvac system

Image Source: Shutterstock

Leaking Attic Ductwork Increases Cooling & Heating Costs In 2 Ways

  • The furnace removes more air from the house than it returns to the house — due to air leaked from the ductwork.
  • To replace the air (leaked from ductwork into the attic) — the furnace pulls outdoor air into the house.

Seal Ductwork To Lower Cooling Bills By Up To 1/3 

  • Typical Forced-air HVAC System Ductwork leaks up to 30% of air (going through ductwork). **
  • When Ductwork Is Inside The Living Space — maximum acceptable ductwork leakage = 3% (in newly built Homes). ***
  • When Ductwork Is Outside The Living Space (like in an attic) — maximum acceptable leakage = 2% (in newly built Homes). ***

** Source:

*** Source:

Before 2012 — Ductwork Sealing Wasn’t Required By Building Code.

Pre-2012 Homes May Or May Not Have Sealed Ductwork.

Beginning In 2012:

  • Building Code Requires Ductwork To Be Sealed.


  • Note: The 2021 Building Code now requires ductwork Leakage Testing in ALL new homes (regardless of ductwork location).

On A Side Note: SOME New Homes Have Ductwork Located Inside The Living Space (Hidden From View).

  • Sealed attic ductwork doesn’t correct the other problem — attics may reach 170 degrees during summer.  Or, reach outdoor temperature during winter.
  • In some areas of the U.S. — Some new homes without basements don’t have attic ductwork.
  • Instead, homes can be designed & built with all ductwork inside the living space — AND hidden from view.
  • This keeps ductwork close to the indoor temperature.
  • The ductwork doesn’t have to be REcooled/Reheated — each time the A/C or furnace runs.
  • One method is to build the home with 9-foot ceilings — with 8 feet ceilings in hallways.  Ductwork is installed in the 1 foot of space above the ceiling.
  • Other ways include adding a Soffit or Bulkhead:  These are a section of ceiling that has been lowered (along a wall) — and enclosed.
  • Then all ductwork is located within the 8 feet ceiling height & soffit areas.

Copy The Link Below Into Your Browser To See Photos + Read An Article About Hiding Ductwork Inside Soffits:

3 Ways to hide duct work: what are your options?

Before 2012 — Ductwork HVAC Ductwork Testing Wasn’t Required

Lower Cooling Bills In Your Pre-2006 By Testing & Sealing Ductwork.

  • In many cases, the ductwork was never sealed for air leaks when the home was built.
  • Some home-builders may have sealed ductwork — and others didn’t.
  • If duct tape was used, it failed within days.
  • If sealing products (other than mastic or aerosol) were used — many have failed over the years due to attic heat (which can reach 160 degrees during a sunny summer day in DFW).

Starting in 2006 The International Energy Conservation Code (IECC) began requiring HVAC Ductwork Testing.  If the HVAC ductwork has been replaced — it may have been sealed when installed.


NOTE: Most States’ building codes match the IECC requirements.

Starting In 2006, IECC Added:Duct systems Shall Be Made Substantially Airtight with; tapes, mastics, gaskets, or other approved closure systems.”  But, without HVAC Ductwork Testing, There Was NO Way To Know If, Or How Well, HVAC  Ductwork Had Been Sealed.

  • Aerosol Sealant was not mentioned — because it’s typically not used for newly-built homes.
  • It performs very well — when applied to ductwork in existing homes (details in Part-2).

Today, most newly installed ductwork is sealed with Mastic.  Mastic doesn’t dry & harden like some other ductwork sealing products.  If the ductwork is currently sealed with mastic, it’s likely to stay sealed for many years.



 Testing HVAC Ductwork For Air Leaks-1 

This is Part-1 Of Our Article Details Testing Ductwork For Air Leaks — as part of a multi-part article with 75+ Ways To Lower Cooling Bills Without Replacing Your HVAC System.  Al’s Plumbing, in Plano, Texas Provides Full-Service Plumbing; Maintenance, Repairs, and Replacements For Every Plumbing Component In Your Home. 

We sell and install gas and electric water heaters.  Al’s is near your home in; Murphy, TX; Rowlette, TX; and Wylie, Texas.  We service all homes in southern Collin County, TX, and northeastern Dallas County, TX with no additional travel charges.

Call Al’s Today To Discuss Any Concerns Or Problems You Have With Your Home’s Plumbing. 

We will arrange an appointment at your convenience.