One of the most frequent but neglected issues in commercial and residential HVAC systems is the leaking ductwork. Leaks, cracks or loose fittings in air ducts mean that the conditioned air escapes before delivery to its required location. This considerably decreases the comfort level besides causing increased energy bills, poor indoor air quality and more unwarranted burden to your heating and cooling system.
This detailed manual will describe the nature of leaking ductwork, its causes, the symptoms, and the most effective methods of repairing and preventing it. As a homeowner or property manager or HVAC professional, it is worth knowing duct leakage to save money, and also prolong your HVAC system.
What Is Leaking Ductwork?
Leaking ductwork refers to the escaping air of the HVAC duct system that is leaking through the holes, cracks, disjointed joints, or improperly sealed seams. The air does not flow efficiently to living or working areas by delivering warm or cooled air but rather flows into unconditioned spaces like attics, crawl spaces, ceilings or wall cavities.
Ducted studies have shown that impervious ducts have the potential to consume 2030 percent of conditioned air and therefore duct leakage is one of the biggest energy losses in buildings.
Common causes of leaking ductwork
The first thing to do to address the issue is to understand its causes to fix the leaks in ductwork.
1. Poor Installation
One of the major causes of air leakage is improperly fitted ducts. Leakage may occur as early as the initial day due to loose connections, improper sealing and improper sizing of ducts.
2. Aging and Wear
With time the duct materials will deteriorate. Metal ducts can become corroded, whereas flexible ducts can become torn or collapse leaving holes through which air will escape.
3. Vibration and Pressure
The operation of HVAC systems produces pressure and vibration. Such continuous movement may widen duct joints, particularly when these were not initially well fastened or closed.
4. Rodents and Pests
Flexible ductwork or insulation can be chewed through by rodents, birds and insects creating holes that can result in large loss of air.
5. Poor Sealing Materials
Low-quality tape or sealants that dry up and peel off during use may lead to leaking ductwork particularly in high-temperature places such as in attics.
👉👉👉👉Also read: Duct Insulation.
Signs of Leaking Ductwork
Leaking ducts may be concealed behind the walls or ceilings and hence hard to detect. Nevertheless, it has a number of red flags that one should be aware of.
Uneven Heating or Cooling
In case there are rooms that are always too hot or too cold, this is possibly because the ductwork is leaking and the air cannot reach those rooms.
High Energy Bills
Whether you have an unexpected rise in electricity or gas bills may be a sign that your HVAC system is overtaxed trying to replace lost air.
Excessive Dust Indoors
Due to leakage of ducts, dust, insulation particles, and allergens may be attracted to the system, resulting to poor IAQ.
Weak Airflow from Vents
When the airflow is weak with the system operating at full capacity, then there is a possibility that air is leaking out even before it can get to the vents.
Noisy Ducts
Whistling, rattling or hissing noises are also signs of air making it through the gaps or openings.
The reason why the problem of leaking ductwork is significant.
It is not just the discomfort that can be experienced in the long run when ductwork is not addressed when the leakage occurs.
Reduced Energy Usage.
Leaky ducts cause HVAC systems to operate at longer cycles and use more electricity or fuel and the operation costs are high.
Reduced HVAC Lifespan
The additional stress caused by constant overworking (loss of air) results in more and more frequent breakdown and reduced service life of the system.
Poor Indoor Air Quality
Leaks in the air may bring about contaminants like mould spores, dust and insulation fibres into the areas of habitation worsening allergies and respiratory problems.
Moisture and Mold Growth
The ductwork may leak in the humid climate resulting in build-up of condensation within the ducts and adjoining buildings which raise the chances of having moulds on the inside of the ductwork and the buildings.
Diagnostic of Leaking Ductwork.
Visual Inspection
Inspect the exposed ductwork by looking at apparent holes, disconnected parts, or loose connections. Ducts in attic and crawl space should be paid attention to.
Smoke or Incense Test
When the system is running it can be determined that there has been air leaks through blowing away of smoke when smoke is run near duct joints.
Professional Duct Leakage Testing.
Blower door tests and duct blasters are the tools that HVAC professionals use to determine the precise amount of air leakage and the areas of problems.
How to Fix Leaking Ductwork
Repairing duct leaks can be as simple as DIY fixes or as advanced as the professional repair depending on the severity of the leak.
1. Practical Seal Joints using Mastic Sealant.
The best material in sealing leaks in duct is mastic sealant. Liberally apply it to joints, seams and connections and then add fiberglass mesh as needed.
2. Use UL-181 Rated Foil Tape
In comparison to the regular duct tape UL-181 foil tape has been developed such that it does not lose its strength due to heat or moisture.
3. Looseness in Ducts Tighten and Reconnect.
Unattached or hanging ducts must be carefully reattached and well supported to avoid the leakage in future.
4. Replace Damaged Sections
When ducts are accidentally mishandled, ripped up or crushed, replacing them is usually less expensive than the alternative, which is having them repaired again.
5. Insulate Ductwork
Insulating ducts helps in minimizing temperature loss and lowers condensation particularly in unconditioned areas.
Leaking Ductwork Repair Cost.
Repair of leaking duct work will cost according to size of the system, availability and damage.
• Minor sealing repairs: $200 – $500
• Moderate duct repairs: $500 – $1,500
• Complete duct replacement: $2,000 -5,000 or above.
Although repair involves a initial investment, duct sealing can be a self-paying venture in terms of lowered energy expenses in the short term (a few years).
👉👉👉Also read: Ductless Heat Pump.
Leakage Prevention of Future Ductwork.
It is always cheaper to prevent rather than cure. This is what you can do to maintain your ductwork.
Plan HVAC Cleaning.
The inspection is done on a yearly basis to detect small leaks, which can be solved before it spirals out of control.
Use Quality Materials
Ensure you apply high grade sealants, tapes and insulation which are HVAC specific.
Ensure Proper Installation
Engage licensed HVAC professionals who observe the best practices in regards to duct design, sealing and support.
Protect Ducts from Pests
Close holes in the building and keep crawl spaces and attics clean to prevent rodents and insects.
Leaking Ductwork and Energy Effectiveness.
One of the most useful measures of enhancing the energy efficiency of a building is to seal duct leaks. As a matter of fact, most energy saving schemes and green buildings policies lay stress on duct sealing as a fundamental condition. By ensuring leaking ductwork, you can:
• Reduce energy consumption
• Improve thermal comfort
• Lower carbon emissions
• Increase property value
When to Call a Professional
Although small leaks can be resolved manually, a professional need to be called in case:
• Ducts are either unreachable or enclosed.
• Mold or moisture is present
• Basic repairs do not result in low energy bills.
• HVAC system is inefficient or old.
HVAC technicians are professional and can train to carry out duct sealing and testing as well to achieve maximum performance.
Conclusion
Leakage of ductwork is an undetectable issue which may cause tremendous effects on comfort, energy expenses and indoor air quality. Knowing how to prevent it, being able to notice the indicators, and making the necessary measures to fix and avoid leaks will help you to preserve your investment in HVAC and build a healthier and more energy-saving environment.
In case, you have a suspicion that there is leakage to the duct work of your home or building, timely action can save you, make your house comfortable and prolong the life of your HVAC system.
