Stay Comfy Blog

A Homeowner's Guide To Creating A Zoning System


If you have been doing your research on HVACs you may have heard of zone heating – or zoning. Zoning is a way to heat and cool your home by breaking your house into different zones, and then only heating and cooling the areas when you are going to use them. It’s a very effective and efficient way to heat and cool a bigger home, because the larger areas of the home that are not used often or are used on a different schedule than other parts of the home can only be cooled or heated when needed. Here are some basic guidelines when creating a zoning system.

Zoning Can Use Multiple Thermostats And Multiple HVACs

There are many ways to create an HVAC zoning system in your home. Some homes use multiple furnaces/ACs for each zone, and a different thermostat for each area, as well. Others use one furnace/AC combo, then have separate thermostats for each zone that will trigger a set of dampers to open or shut ducts and vents depending on where heating or cooling is needed. And some use multiples of both HVACs and thermostats but still have certain zones share an HVAC and use dampers. It’s all what you and your HVAC professional decide is best for your home and needs. 

Insulate The Home’s Different Zones

If you are going through the effort of creating a zoning system in your home, then it’s also worth the effort to insulate each zone from each other to make the most of your home’s energy use. The Department of Energy says that “in homes not (originally) designed for zone control, leaving one section at a lower temperature could cause comfort problems in adjacent rooms because they will lose heat to the cooler parts of the home. Zone control will also work best when the cooler sections of the home can be isolated from the others by closing doors.” 

That means close doors and make sure they are also well insulated if you want to prevent heat from escaping to cooler areas.

It’s Harder To Do With A Fixed Capacity System 

Our resident HVAC expert, Keith Hill, technical support manager at Minnesota Air, says that zoning a forced air system can be tricky if you have an older fixed capacity system. According to Keith, a fixed capacity system is one where the furnace comes on and you get full heat and full airflow, and then goes off when the thermostat has reached what you set the temperature setting to on the thermostat.

“If we add zoning dampers to this kind of system, essentially splitting up the airflow between multiple ducts, each zone duct would have to be large enough to accept the full airflow of the furnace, or one of two things will happen,” says Keith. “The system may get noisy (air noise) when only one zone damper is open, and the airflow will be restricted as we are trying to put all of the air into one small duct. And if the airflow is too low it may damage the furnace or AC unit.” 

He says that to overcome those issues, many techs will install a bypass damper to act as sort of a pressure relief valve. However, he says that can be wasteful and may cause other issues when the air bypass occurs. 

“A better way is to make modifications to the existing duct system so it can better accommodate the air so that each zone duct can handle the full capacity of the furnace,” says Keith. “But that can be expensive, especially if the existing duct system is over a finished ceiling.”

Zoning Works Best With a Modulating Furnace/AC 

To get the most out of creating a zone system in a home not originally created for zoning is to use a modulating HVAC system. That means a furnace or AC that runs at a steady and more even heating/cooling. It basically micromanages your system to keep the home within a percentage of a degree to where it is set.

“The very best way is to use a modulating Carrier furnace and modulating Carrier AC with an Infinity Zone System,” says Keith. “This system will modulate the heating, cooling, and airflow to precisely match the zones that are active. If only one small zone is calling for heat, then the furnace will fire in low fire, and the blower will run in low speed, so that it will never exceed the capacity of the zone duct. No wasted energy, maintains the furnace and AC efficiency, and it’s really quiet.”

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