What is Zoned HVAC?

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Posted August 9, 2019

The global HVAC systems market is expected to reach approximately $173.16 billion by 2022. Besides the traditional HVAC systems, the market is experiencing exponential growth of zoned HVAC systems. Their popularity is based on their ability to divide a home into different temperature zones.

The demand for zoned air conditioners varies from one region to another because of variances in climate. The type of buildings in question and heating and cooling requirements also influence demand. This has led to fierce competition among manufacturers.

With all the many types of zoned air conditioners available, what are your options? Read along so that you can make an informed decision.

What Are Zoned Air Conditioners?

Zoned HVAC systems refer to heating and cooling systems that regulate and redirect air to specific areas of the home.

They are also known as HVAC zoning systems. Their purpose is to create customized temperature zones within the home for improved efficiency and comfort.

Zoned HVAC systems work best in homes where the occupants have different temperature preferences. The systems make it possible to accommodate the varying needs while also saving on energy.

The systems are also ideal for homes with large windows or a top floor that’s always warmer than the rest. Rooms that are rarely used and feel stuffy are also candidates for zoned HVAC systems. You can also consider it for additional areas like the gym, which need additional cooling.

If your home has two or more stories or raised ceiling plates, consider installing zoned air conditioners.

Components of HVAC System

A zoned system is a single system designed to serve two or more zones at the same time. Note that it doesn’t mean that you have to install two separate units. The components of a zoned HVAC system are:

The HVAC System

An HVAC system that features a furnace combined with an AC, an air handler, and a heat pump. It also comes with 1-20 or more motor-driven dampers. Their purpose is to control the flow of air to each area.

Zoned HVAC Units


The ductwork design determines the number of dampers the system requires.

Each major branch of the trunk may need a damper, besides the smaller branches. Overall, a zoned air conditioner system requires few dampers than a retrofit.

The control of the dampers is such that they can open or close entirely. Instead, a modulating controller can be installed to open the dampers at partway to meet the demands of each zone. This installation will come at an extra cost.

Temperature Control

The other component is temperature control and monitoring device in each. It makes it possible to monitor each zone separately and adjust the temperatures accordingly.  The temperature control devices are installed in one of two options.

The first option is to have a thermostat in each zone to control and monitor the temperature. This is the simplest method.

Option two is to have a system with multi-zone thermostats and sensors. This means that each zone will have the sensors, which will relay information to the central thermostat. In turn, the thermostat controls how each area becomes air conditioned.

The multi-zone thermostat comes with the advantage of letting you control your system from one location. However, it’s worth noting that you can control any single or multi-zone thermostat from anywhere using a smart device. For this to happen, it must be Wi-Fi enabled.

Let an HVAC professional advise you on the best mix of sensors and thermostats.

Damper Control Panel

This is the platform on the HVAC system that receives information about the desired temperature level in each zone. With this information, it’s able to control the dampers to control airflow in a way that satisfied the cooling and heating of each area.

Wiring or Wireless

The wires are essential for connecting the dampers back to the control panel. On the other hand, sensors and thermostats can be wired and wireless.

Advantages and Disadvantages of Zoned HVAC System Design

One of the most significant benefits of zoned systems is their ability to set different temperatures for different areas. They let you create as many zones as possible, reducing energy wastage. You avoid heating areas that need cooling and vice versa.

According to the U.S Department of Energy, homeowners can save between 20 and 50% on their heating and cooling bills. The system also lets you regulate energy in areas that aren’t frequently used, especially in summer and winter.

Extra Control and Comfort

A zoned air conditioner gives you more control over temperature regulation. It lets you eliminate unnecessary hot and cold spots around the home. It means that everyone enjoys the temperatures they prefer.

If you’re using a programmable thermostat, you can control the temperatures remotely.

A business that deals with fresh produce can benefit from a zoned HVAC system. The firm can create a cold room where the temperatures are kept low to protect the products.

Improved Air Quality

Zoned systems keep the air in one room from spreading to other rooms.

This helps keep pet dander, dust, and pollen from spreading throughout the entire house. If you’ve got people who are susceptible to allergies and asthma in your household, their probability of getting attacks is reduced.

In the long run, a zoned HVAC system is an investment that keeps everyone in your home happy.

Disadvantages of Zoned HVAC

On the downside, once your system develops a problem, troubleshooting can be difficult.

The multiple components can take a lot of time to scrutinize one at a time. The process can end up being costly, especially for a business premise.

They also are more expensive to install, requiring an upfront investment. They’re also more complex than traditional units. This means that they need more control units to be fitted for increased versatility.

The increased complexity of the system also calls for more maintenance. You’ll require regular checkups from a professional technician to keep the system running well.

Despite these drawbacks, zoned air conditioning systems may still be the solution you need for your situation.

How to Tell Between Good and Bad Zoned System Design

An HVAC system that isn’t zoned heats or cools every area of the building at the same time whenever it’s running. Think of having all the lights in your home turn on when you switch on any light. The lights in any unused rooms end up wasted.

A zoned HVAC system stops heated or cooled air from going to unoccupied rooms. If installed the right way, zoned systems will pay off immediately and start saving you money monthly.

How do you tell if you’ve got a good zoned system design?

First, you need to know that good design starts with a variable-capacity or two-stage HVAC system. Two-stage systems run on a low of 65% and a high of 100%.

As such, consider what happens if the demand for heating or cooling in various zones reduces by one-third.

When this happens, your home will be running at about two-thirds or 66.7% of the system’s capacity. It’ll run at a low most of the time, reducing energy and cost by about 30%.

The ductwork splits to serve three sections of the home. Without a zoned system, each part would use up 33.3% of airflow at all times, adding up to 100% energy usage. The bottom line is that you make no savings on energy on costs.

How Do Zoned Thermostats Work?

The multi-zone thermostats are set to make different areas get disproportionate amounts of cooling or heating. This reduces the total capacity of airflow that passes through the system. For example, rooms in the upstairs could get 20% of the system capacity.

The family room and kitchen could get 30%, while the rest of the rooms get 15%. This totals to 65%, which is the ideal capacity for a two-stage HVAC system.

An experienced HVAC technician should help you with setting up these capacities. They’ll determine the range of temperatures for each zone. The aim is to ensure the entire system runs at a low while keeping all areas of your home comfortable.

Comparing Zone HVAC vs Non Zone HVAC

Identifying a Bad Zoned System Design

Two significant flaws occur with zoning systems.

1. Single-Stage Systems Shouldn’t Be Zoned

Single-stage systems can’t be zoned because they operate at 100% capacity whenever they’re on. This means you can’t reduce the energy use in any when the system is at full capacity.

When the system is 100% capacity, the air has to go somewhere. If any of the zones are shut, the excess air will find its way through the open zones. This will result in too much heated or cooled air flowing through the open zone.

Eventually, the system will run in short but frequent cycles which can result in mechanical failure or temperature swings. You’ll have rooms that are either too hot or too cold. All that airflow will cause whistling or rushing in the ducts, causing leakages or damage to the pipes.

2. Bypass Dampers and Ducts Shouldn’t Be Used

A bypass damper connects one end of the trunk to the zoned branches. This is the trunk that supplies heated or cooled air. On the other end, it connects the trunk to the return air plenum where the air returns for re-cooling or reheating.

At the center of the duct is a damper that closes when all zones are open so that no air goes through. When one or more zones are closed, it opens partially, causing air pressure to build in the system.

A bypass becomes necessary in single-staged and zoned systems to prevent airflow and ductwork problems. The excess air is pushed to the partially open or closed dampers and pushed back to the bypass. The gushing of air forced through open zones is eliminated.

With all this process, the problem of airflow doesn’t become resolved. Here are the reasons why bypass ducts shouldn’t be used in single or zoned systems.

  1. The bypass doesn’t reduce cooling or heating in a single-stage system that runs at 100% capacity. The bottom line is that you make no energy savings.
  2. When the system is running, forcing cold air into the handler can make the AC coil freeze. This increases the system’s inefficiency and can block the flow of air completely.
  3. Most bypass dampers are not wired but are instead weighted. The more air pressure caused by the closed dampers, the wider they open. When all zones are open, air finds its way to the bypass duct, and the cooling and or heating goes to waste.
  4. Bypass dampers easily collect humidity and eventually grow mold.

This opinion is from a professional view against bypasses. If your HVAC installer suggests installing a system that has a detour, you’re better informed to make a decision.

What Are Your Options?

When should you consider using a zoned air conditioner? If your HVAC system is two-stage, variable capacity, or has a blower with variable speed, consider installing a zoned system. Besides, it can be useful when you have unoccupied areas in your home.

Temperature imbalance issues are also a reason for you to consider zoned systems. If some areas in your house are too warm or too cold, a zoned air conditioner will help. Zoning helps in target heating and cooling hence leading to less total use.

Final Thoughts

When installing heating, ventilation, and air conditioning systems, there are lots of models you can consider. Among them are zoned and non-zoned HVAC systems.  Each type affects how the different rooms in your house heat up or cool down.

Zoned air conditioners come with different sensors for separate zones. You can control the temperatures of different rooms from a central point. The members of the same household can have their temperature preferences met.

A zoned HVCA system helps cut down on energy costs. The different zones operate at a low consumption level when running. This differs from a non-zoned system that runs at 100% all through.

If you’re unsure about anything to do with your HVAC system, let a professional installer guide you.

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