When upgrading your HVAC system, the focus is often on the new equipment—furnaces, air conditioners, or heat pumps. However, one crucial component that can make or break a system is often overlooked: ductwork.

Poorly constructed ductwork can lead to inefficient system operation, decreased home comfort and poor air quality, as well as causing wear and tear on the system.
The Role of Ductwork in Your HVAC System
Unlike ductless systems, which require individual units in each room, central systems use ductwork to distribute air from one unit to multiple rooms.
Ductwork acts as the circulatory system of your HVAC structure, delivering heated and cooled air to each room and then recirculating it for even distribution throughout the home.

When deciding between ductless or ducted HVAC systems, it’s important to consult a qualified contractor to help you navigate the advantages and disadvantages of each option.
If you choose to use a ducted central system for your home, be sure to consider ductwork design as closely as the rest of the system components.
Consequences of Poorly Constructed Ductwork
Reduced System Efficiency
According to Energy Star, leaky ductwork can reduce system efficiency by as much as 20%, potentially negating the new upgrades made to your HVAC system.
Undersized ductwork can also restrict airflow, forcing your HVAC system to work harder to heat or cool your home. This can lead to increased energy consumption and higher utility bills.
Uneven Heating and Cooling
Failure to properly size and/or install ductwork can result in uneven heating and cooling throughout your home. For instance, some rooms may feel too hot, while others feel too cold, leading to discomfort and the need to constantly adjust your thermostat. This is not an efficient or cost-effective way to run your system.
Increased Wear and Tear
A less obvious repercussion of poorly designed ductwork is the unnecessary strain it puts on your HVAC equipment.

An inadequate ductwork installation causes your system to work harder to properly cool/heat your home. This results in increased wear and tear on your system, potentially shortening its lifespan.
Air Quality Issues
Leaky ducts can allow dust, dirt and other contaminants to enter your home’s air supply. The ramifications of this are often poor indoor air quality and, in some cases, potential health issues.
The Importance of Manual D Calculations
So, how do you avoid over/under-sizing ductwork? Proper Manual D calculations.
Manual D is a method used to properly size and design ductwork for HVAC systems. This calculation considers factors such as the size of your home, the layout of your ductwork (current and/or future) as well as the capacity of your HVAC equipment,
Conducting a Manual D calculation ensures your ductwork is properly sized and designed to deliver the right amount of airflow to each area of your home.
Choosing a Qualified Contractor
When installing a new HVAC system or upgrading your existing system, it’s crucial to choose a contractor who is experienced in designing and installing ducted HVAC systems.

A qualified contractor will conduct a Manual D calculation to ensure your ductwork is properly sized and designed for optimal performance.
We strongly advise against working with contractors who outsource the Manual D and/or Manual J process. Outsourcing these When these calculations risks miscommunication or lack of understanding between the contractor and the third party. This often results in poorly designed ductwork.
A reputable HVAC contractor should explain their system design/installation process and answer any questions you may have.
Properly designed and installed ductwork is essential for the efficient operation of your HVAC system. Understanding the role of ductwork and the importance of Manual D calculations, can help you avoid costly mistakes and ensure that your new HVAC system provides reliable comfort and energy efficiency for years to come.
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