Is Your HVAC System Ready for Zoning?


If you have a large home, heating or cooling your home can be an immensely difficult task for your HVAC system. If your entire home relies on one central heating or air conditioning unit, then this unit must be able to output a substantial amount of air, which requires a lot of energy. These single-unit system are typical, but often they result in uneven heating or cooling and massive energy bills because they must run heavily, particularly in larger homes. To combat this, many homeowners have begun zoning their HVAC systems.

What Is HVAC Zoning?

Zoning is the practice of dividing your home’s HVAC system into sections by creating separation between different duct and vent systems. When your home is properly zoned, your system only needs to heat or cool a much smaller area at a time, which means it doesn’t need to run as often which saves you money. It also usually results in better comfort since your system will have a much easier time heating or cooling the most difficult-to-reach rooms in the house. For multi-story homes, this can be a huge benefit. Since heat rises, homeowners can choose to air condition only the upstairs rooms when necessary and then heat just the bottom floor during winter.

However, zoning can come with some added challenges, and while it’s highly likely that you can zone your home’s HVAC system and ductwork, it may not be the most practical choice. The first thing you should inspect is what type of heating or air conditioning system you have, specifically in terms of how the blower motor operates.

There are three primary types of HVAC systems:

  • Single-stage
  • Two-stage
  • Modulating

Single-Stage Systems

Single-stage systems have two settings: on and off. When your system switches on, the blower motor operates at full speed and full power until the thermostat instructs it to switch off again. This is fairly common in most homes, particularly those with older HVAC setups. It’s not advised that you zone your HVAC system when you have a high-power single-stage system.

Let’s look at an example: say your air conditioner is rated for 30,000 BTUs. If you split your home into two zones, suddenly your 30,000 BTU system will only need approximately 15,000 BTUs to cool each zone, so it’s twice as powerful as it needs to be. This may not seem like a big deal, but systems that are too large for their area will frequently begin short-cycling, or switching on and off rapidly, because the system is too powerful for the zone it’s handling. This leads to immense wear and tear on your HVAC system, blower motor damage from too much amperage draw, motor, igniter, and inducer burnout, furnaces overheating and air conditioner coils freezing into a block of ice, and many other problems that require extensive and costly repairs.

Some less-reputable HVAC repair and installation companies who offer to zone your system on a single-stage setup often either don’t know what they’re doing, or then come in when the system fails and offer massive repairs while selling a true zoning system. Others will suggest installing a dump damper, which funnels excess air back into the system, allowing a single-stage HVAC system to function smoothly and limit motor blowout, but recycling already-conditioned air still leads to short-cycling, and the wear and tear associated with it.

Two-Stage Systems

A two-stage HVAC system has two blower levels: full-blast, or a reduced capacity (usually around 65%, depending on the manufacturer). With one of these systems, when a smaller zone calls for heat or air conditioning, the system will run at that reduced capacity, alleviating a number of the issues that a single-stage system can have.

However, these systems are not perfect. If one of your home zones is less than 65% of your home, your system will still begin to short-cycle when cooling or heating this area, resulting in further wear and tear to the blower motor and other components.

Modulating Systems

The best option when it comes to heating or air conditioning a zoned home is a modulated system. Modulating furnaces will run anywhere from full capacity all the way down to 35% (or as low as 25% for air conditioners) depending on the manufacturer. This is the best option, since your system will adapt to each individual zone in your home. It’s fairly easy to zone your home so each section is at least 35%, which means you won’t have to worry about the typical problems that come from zoning a single-stage or some two-stage systems.

For help with zoning your Milwaukee home’s HVAC system, call Burant Heating and Air Conditioning now! Dial (414) 386-3660 or contact us online to schedule an appointment.

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