Can You Add Too Many Ducts To A HVAC System

More than one duct added to an HVAC system can work properly
  • Author: Amanda Arnold
  • Posted On: November 6, 2022
  • Updated On: August 21, 2023

It’s a scorching summer day, so you turn on your cooling system to get rid of the humidity in your house. It is clear from the circumstance that your system is operating, but the advantages are not being felt in your home.

The network of ducts that distribute air from your HVAC system to the many rooms in your house is the issue here, not your HVAC system itself. You might not give them much thought, but the truth is that even a minor fault with your ductwork can significantly impact system efficiency.

Although the power of an HVAC system is closely correlated with its size, you will need more than an excessively large HVAC system for your home. Depending on your home’s size and area, HVAC systems must be appropriate.

The amount of conditioned air you need will be available from a unit that is too small for your home if it runs nonstop.

Things To Consider Before Adding More Ducts To HVAC System

Duct Size

Not just the size of the HVAC unit but also the size of your ductwork is important. Similar issues as those brought on by an improperly sized unit will also be brought on by improperly sized ducts, ultimately placing too much pressure on your unit.

The size of your home, the airflow rate, friction loss, and the HVAC system’s static pressure are just a few variables that affect duct sizing.

Home’s Area

Your home’s overall size and the dimensions of each room affect the size of your ductwork. Therefore, while deciding on ductwork sizing, it is necessary to measure the total square footage of the home and the square footage of each room.

It’s better to leave it to an HVAC specialist to calculate the total square footage of your home because it could be difficult.

Velocity Of Required Air For Cooling Or Heating The Rooms

The quantity of air needed to heat or cool each room in your home is measured in cubic feet per minute (CFM). The size of the duct system directly affects the airflow or velocity. To determine the size of the ducts to be placed, it is essential to determine the CFM of each room.

Friction Rate

The speed at which ducts lose frictional heat affects how much air your system can move. The static pressure for your HVAC system along the entire length of the ductwork can be understood by contractors by measuring this rate.

Furthermore, the length of each duct, the number of grilles, registers, dampers, and turns in the ductwork are all important variables that affect friction loss rate. Even though friction loss calculators are online, it isn’t easy to arrive at this amount. Hence it is best calculated by qualified contractors.

Ways To Improve Your Already Installed HVAC System

The downstairs of a two-story house without any zoning is always comfortable and cool. Since the thermostat is located there, you can be sure that the temperature inside will match the reading on the thermostat.

You add two zones—one for upstairs and one for downstairs—to your current system to address the issue. However, the air conditioner you are using is a typical, single-stage one with a single-speed blower.

It is the type that only operates at full throttle or not at all.

Install Dampers Into HVAC Ducts

The most popular method for including more zones in an existing system is to install dampers inside your ducts. Your blower, however, can only work at full capacity. Only the ductwork connected to a single zone can handle the static pressure because it is too high.

You’ll need a method for rerouting the surplus air.

Add A Bypass Duct

To handle the additional air your HVAC system generates, you’ll probably require a bypass duct linking your supply air to your return plenum. Any surplus air will enter the bypass duct once the area where the zone calling for air is located has had enough cooling to chill it.

Because you are currently returning cool air to the return, your evaporator coil gets colder. A lower temperature indicates a less efficient evaporator coil. Even though the entire home may be cooling, the bypass duct will still suck air from the supply.

You will cause your air handler to have to work harder. Ultimately, you’ll have two zones, but you’ll lose efficiency and put more stress on your equipment.

Is It Suitable To Add More Ducts Into A HVAC System?

In certain cases, but only sometimes, adding one or two zones is a wise decision. Only after you have optimized the building envelope should you add zones if you still feel uneasy. Or, enhance insulation first, then plug any air leaks.

You can address your comfort issue without changing the ductwork or HVAC system! A house assessment by a Building Performance Institute-certified auditor is the most effective technique to determine whether zoning is a smart idea.

If your home has leaks, you’ll learn about it and be in the best possible position to fix it.

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Author: Amanda Arnold

Amanda has been working with ConstructionHow since 2021. Her experience spans over 5 years in the creative niche such as home decor and trends, landscaping, renovations, and custom architectural values. As a home designer expert, she has a keen eye for the latest home improvement trends with accurate facts that readers find impossible to ignore. Being invested in home-building trends is how she has gained her lucrative expertise exploring more to bring a positive ambiance for all homeowners (and even tenants!). Currently, she lives in a beautiful beach home, a source of fascination for her.