heating and cooling

Zoning Systems: How They Operate and What Benefits They Provide

Aug 19, 2014 | Articles

Keeping your entire home comfortable and trimming energy bills are the most significant zoning system benefits homeowners reap when they zone their homes. A zoned home is divided into separate areas based on different needs for cooling and heating. Without zoning, temperatures can vary widely throughout the home based on a room’s orientation to the sun, level in the house, and a host of other factors.

Homes that have the same conditioning requirements throughout the structure are rare. A house has exposure in all directions to the sun and wind that can make a difference in temperatures throughout the day. A living area that faces south may be cozy in the winter, but exceptionally warm in the summer.

How They Work

These systems work by opening and closing motorized dampers inside the ducts based on the particular zone’s need for conditioning. Each zone has its own thermostat that connects to a central control panel. The control panel sends a signal to the HVAC system, which turns it on and off in a room or zone based on the thermostat’s settings. At the end of the cycle, the dampers close and won’t reopen until the thermostat triggers the control panel again.

Suitability

Homes that have any of these characteristics are appropriate candidates for a zoning system:

Homes with two or more stories
Homes with finished basements
Those with unused areas
Homes with large expanses of windows, especially on the south or west sides
Sprawling homes
Families whose members have different temperature preferences
Homes with raised ceiling plates or vaults in some of the rooms
Homes with finished, livable areas in an attic or over the garage

Benefits of Zoning Systems

Energy savings. Since a zoning system only provides conditioned air to the areas that need it, it won’t use as much energy as a single zoned home. This cuts cooling and heating bills.
Increased comfort. An evenly comfortable home could be one of the most important zoning system benefits. During the cooling season, rooms that have south and western exposure are typically much warmer. Setting the thermostat to accommodate the extra heat gain can overly cool the rest of the home and drive up energy consumption. Multi-story homes are particularly hard to keep comfortable, especially in the summer as the heat in the attic builds and heat in the home rises to the upper floors. Most two-story homes have the bedrooms placed upstairs, and keeping them comfortable at night without over-chilling the downstairs is easy with a zoning system. Kitchen and family rooms are another area where heat tends to build faster than other areas in the home.
Quiet operation. The HVAC system won’t need to run at top speed each time it turns on, which quiets its operation. Anyone whose bedroom is near the air handler will appreciate a lower noise level when the system does turn on.
Effortless operation. When you combine a zoning system with programmable thermostats in each zone, you won’t have to remember to turn them up or down based on when you use that space. Combining a system with WiFi thermostats gives you remote control over the temperatures in each zone of the home. If you won’t arrive home until later than you planned, you can simply delay the time the system turns on.
Prolong system life. Any HVAC system that doesn’t have to operate at full speed will last longer, since there’s less stress on the components.

Installation

The easiest way to reap zoning system benefits is with a new heating and cooling system designed for zoning. However, the systems can be installed in retrofit situations. Dampers are available for standard ductwork sizes. Your HVAC contractor can show you the options available that will work with your system, its ductwork configuration and your home’s floor-plan layout.

If you’d like to learn more about zoning system benefits, contact the NATE-certified professionals at Air Specialty. We’ve provided superior HVAC services for homeowners in the Mobile, Ala., Saraland, Ala., and Lucedale, Miss., areas since 1993.

With Good Ductwork Design, You’ll Boost Your Budget

Jun 27, 2014 | Articles

Between your furnace or air conditioner and creating a comfortable environment in your living spaces you can find the principles of proper ductwork design. Airflow is your system’s life force, and ducts are the conduit that makes your home a livable, energy-efficient environment. Unfortunately, the reverse is also true. Where ducts are not accorded appropriate attention and priority – whether in the ductwork design and layout or the installation of the ducts – a variety of problems relating to high operating costs, low comfort and even unhealthy indoor air quality may plague the homeowner, often going unresolved for years or even decades.

Best Air Duct Guidelines

Proper ductwork design has multiple objectives:

To distribute conditioned air in appropriate volume to all rooms in the home and at a consistent temperature to meet thermostat settings.
To balance supply air entering each room with return air drawn out of the room in order to produce neutral air pressure, the optimum condition for best comfort, performance and energy efficiency.
To allow your furnace and air conditioner to meet manufacturer’s efficiency ratings while placing minimal load and wear and tear on the system.
To prevent infiltration of unconditioned air into the system and avoid contamination of indoor air quality.
To keep operating costs low and reduce the environmental impact of your home.

Duckwork Should Be Calculated

None of the above happens by accident, nor by guesswork or applying ballpark estimates instead of proven scientific design methods individualized to each specific home. While ductwork design often received less consideration in past eras of cheaper energy, today it takes proper precedence in new homes and is often included in renovation plans for existing homes, where ducts can be upgraded as part of the project. Getting from the ductwork design goals above to a working system that performs under the day-to-day, all-season demands of the average household means adopting certain established tenets of good ductwork design that are standard in the industry.

Calculate cooling and heating loads first. Using Manual J, the industry-standard load calculation software, the exact amount of BTUs of heating and cooling required to keep each room comfortable can be accurately determined. From this data, an HVAC professional can utilize the Manual D duct sizing program to figure the supply air requirements of every room and the diameter of the ductwork necessary to deliver that volume.
Take the shortest and straightest route possible from the air handler to each room. Reducing the physical length of ductwork by using proper design principles increases energy efficiency and performance. Unnecessarily long spans, as well as the excessive use of curves, bends and elbows in ductwork layout, create internal air friction that increases the effective length of ductwork far above its actual physical length.
Use conditioned routes if possible. Design the layout to route as much of the ductwork as possible through heated or cooled zones of the home. Where ducts must pass through unconditioned zones like the attic or crawl space, insulate against thermal loss or gain to a level of R-8 for supply ducts and R-6 for return ducts.
Include a dedicated return duct for every room with a supply register. Where the ductwork design mandates a single central return, instead provisions such as air pass-through grills or jumper ducts connecting rooms without returns should be made to ensure a clear air path back to the central return.
No substitutes for the real thing. Most local codes today prohibit using structural cavities in the house such as the spaces between ceiling or floor joists or interior wall voids as a replacement for proper ductwork. Use only “hard” ducts of sheet metal, fiberboard or approved flexible ductwork.
Make air balancing easy. Designs should specify manual dampers in each branch duct to facilitate air balancing to individual rooms. These should be located at the take-off point where each branch duct diverges from the main trunk duct.
Mechanically secure all spans of ductwork with sheet metal screws or other fasteners, then seal each joint with mastic. Using a standard duct blower method, pressure-test the finished system to check air flow and verify leakage. Most local codes today enforce maximum allowed leakage specs for new ductwork or when installing upgrades to existing systems. Permissible leakage varies per location, but typical figures average around 6 percent of the total airflow volume for new construction or 15 percent when existing ductwork is being replaced or a new A/C or furnace installed.