Heating and cooling all the areas of a house at the same temperature has never been ideal. To start with, different members of the family have different cooling and heating needs and hence there will always be a tussle over the thermostat.
Secondly, due to how air moves while heated or cooled, you will notice that you will have cold and hot spots in the house most of the times. This is especially the case if you have a storied house.
An HVAC zoning system is designed to solve this problem. So. What is an HVAC zoning system and how does it work?
An HVAC zoning system or simply “Zoned HVAC” is a cooling and heating system that separates different areas of a house by their cooling and heating needs thereby creating zones. Each zone has its thermostat and dampers (central air) which regulate its temperature independent from other zones.
Zoning allows cooled air or heat to be delivered where it is needed and at the right temperature. You therefore won’t have to deal with cold basements and hot upper floors.
Zones can be added to an existing HVAC system. To do that, a licensed HVAC technician will help you decide the number of zones you need, then they will install a thermostat in each zone followed by dampers in the ductwork. The zones will then be connected to the HVAC system using a control panel.
All the rooms in your house cannot be converted into zones. A zone cannot be too small since the system will be unable to cycle the air properly.
In short, a multi-zone HVAC system works by creating different zones in a house, each with its own thermostat and moderating damper. When a thermostat calls for cooling/heating, the damper to that zone opens while the rest closes. That allows air or heat to flow and only condition that zone.
So is HVAC zoning worth it?
HVAC zoning is definitely worth it. It is especially helpful in multi-storied houses which have a hard time balancing the temperature in all the floors. HVAC zoning is also energy-efficient and also important if there is a family member with very specific cooling and heating needs.
Types of HVAC Zoning Systems
As I am sure you already known, there are different types of air conditioners. Zoning is usually done in central air (ducted) and ductless air conditioners.
There are 3 types of HVAC zoning systems. They are:
- Dual/multi-zone HVAC System
- Ductless HVAC zone system
- Dual-Unit HVAC zone system
Let us now look at each of them in more details.
1. Dual HVAC Zoning Systems
Dual or multi-zone HVAC zoning systems are found in central air conditioners. They are the most common type of HVAC zoning systems.
In traditional central air conditioning systems, you have a thermostat central located in the house to control the temperature of the whole house. That is like controlling the lighting in your house using a single switch.
To create a dual HVAC zone, you will need to install a thermostat in every area of your house that you need to make a zone. That thermostat will be set to the preferred temperature in that zone which can be same or even different to the other thermostats.
Apart from thermostats, you will also need modulating dampers for each zone. The dampers are placed inside the air ducts or at the air outlet.
An HVAC damper basically is a device that regulates the flow of air/heat from the air handle to a given area/zone of the house by closing or opening. Dampers can either be manually operated or automatic.
To enjoy the full benefits of a zoned HVAC system, I would advise that you install automated dampers.
The dampers and thermostats are then wired and connected to a control panel (located somewhere near the furnace/air handler). The HVAC system is also connected to the control panel.
It is important I mention here that a dual HVAC zoning system has only one condenser unit outside the house and one furnace/air handler inside the house. This system is often confused with a dual-unit HVAC zoning system.
The way a dual zone HVAC system works is that if a certain thermostat calls for heating, the damper to that zone opens while all the other dampers closes. That allows air/heat from the air handler to flow to that specific zone until it is properly air conditioned.
Once that zone is cooled or heated as per the thermostat setting, the damper closes in preparation for the next zone. When all the zones are well air conditioned, the entire systems turns off.
Note: Dual zone HVAC systems work on two-stage air conditioners (which have a variable speed blow on the furnace/air handler) but not a single-stage air conditioner. Such ACs are usually more expensive to purchase but more efficient to run.
Dual zone HVAC systems can simultaneously heat an cool a room. The order of preference depends on which thermostat calls for air conditioning first.
However there is usually a delay between the cooling and heating operations which helps to prevent the system from damage. For instance if the first action was to cool a certain zone, there will a delay between then the damper to that zone closes and when the damper to the zone that needs heating opens.
2. Ductless HVAC Zoning Systems
As its name implies a ductless HVAC zoning system does not use air ducts to supply cooled air to the various spaces in the house. Instead, an inside unit mounted on the wall, floor or ceiling pulls air directly from the house and cools it before circulating it back.
In a ductless HVAC zoning system, you will have one big condenser unit outside the house and several indoor (evaporator) units inside the house, one in each room/zone.
All the indoor units are connected to the outside unit through refrigerant lines. Check out this post to learn more about how ductless air conditioners work.
Each indoor unit can be set to a different temperature setting as the cooling or heating need of that space will dictate. These units come with wireless remote controls meaning you can adjust the temperature from the comfort of your bed or couch.
In smart ductless HVAC zoning systems, the temperature settings of the different zones in the house can be accessed and programed from a smart phone.
One of the advantages of ductless HVAC zones is that there is no air/heat loss. It is estimated that about 20% of the cooled air or heat in central HVAC systems is lost to leaks in the ductwork.
It is more expensive to install a ductless HVAC zoning system than a central HVAC system, assuming you already have ductwork in place. However, when installing both from scratch, ductless systems are cheaper to install.
The main disadvantage of ductless HVAC zoning systems is their imposing presence on the wall. For most people, having such an appliance on the wall interferes with the interior aesthetics of the house.
Ventilation in ductless HVAC systems is also not as good as that in central air/dual zone HVAC systems. For a detailed guide on the differences between central air and ductless HVAC systems check out this post.
3. Dual-Unit HVAC Zoning System
This is the HVAC system that most folks confuse with dual-zone HVAC zoning system. But how different are they?
In a dual-unit HVAC zoning system, there are 2 sets of air conditioning units. You will need two condenser units, 2 furnaces/air handlers as well as 2 thermostats. As such, the two units will run independently.
This set up allows you to have 2 zones in a house. It is however not a very common zoning system for several factors.
To start with, the cost of purchasing and installing 2 separate air conditioning units is quite high. The cost of running the units will also be high and hence this system is not very energy efficient.
A system that is not energy efficient means you will need to pay more in terms of electricity bills. Repairs and maintenance costs of this system will be high as well.
If what you need to do is take care of a certain hot spot in the house, a cheaper and practical alternative would be to install a portable air conditioner. The portable air conditioner will cool that zone and fix the problem.
You could also explore the possibility of installing a window air conditioner. Check out the differences, pros and cons of window and portable air conditioners in this post.
A dual-unit HVAC system makes sense when your house has a rental unit (probably the upper floor) where the tenant will need control of their thermostat. If not for that, I would just stick with a dual/multi-zone HVAC zoning system.
Advantages of HVAC Zoning Systems
There are many benefits associated with HVAC zoning systems. The following are some of the main ones:
1. High Efficiency
With a zoned HVAC system, you use less energy to heat and cool your home. As I have explained, the HVAC system will diverted air and heat from where it isn’t needed to where it is needed and after air conditioning the zone the unit will turn off.
A high efficiency HVAC system translates into lower electricity bills. When looked as a long-term investment, zoned HVAC systems makes a lot of sense.
As a matter of fact, the United States Department of Energy estimates that you can save as much as 30% of your heating and cooling cost by having a zoned HVAC systems.
2. Excellent Air Conditioning
It is very frustrating when you have to deal with cold and hot spots in your house. If the hot spot is somewhere in your bedroom (or that of another family member), it becomes very difficult to get quality sleep.
With a zoned HVAC system, cold and hot spots in the house will be a thing of the past. It also allows the different members of the family to enjoy and have a comfortable time indoors which is essence why air conditioning was invented.
For example, this systems allows your baby to enjoy its nap in a warmer bedroom while your home office remains a little colder for better concentration.
3. It is Good for the Air Conditioner
Without zoned systems, you are forced to blast your conditions to at least get some form of cooling on the top floors of your house. The air conditioner components therefore have to work harder to achieve that.
The harder the air conditioners components work, the more they are subjected to wear and tear (especially the compressor) which shortens their lifespans, or you are forced to have regular repairs.
In short, a zoned HVAC system is likely to last longer than one which is not zoned all other factors held constant.
Who Needs an HVAC Zoning System?
Even with their many benefits, zoned HVAC systems are not for everyone. Installing them in some areas will not be advisable but these systems will be a great option for some people. So how do you known if you need a zoned HVAC system?
You need a zoned HVAC system if:
- You have a multi-storied home
- There is a basement in your house (finished or unfinished)
- Your house has high ceilings or has a loft
- There is a living space in the attic
- The house has one or more wings
- Some rooms have expansive windows
- There are rooms that are rarely used
- A member of the family has specific heating or cooling needs that are different from those of others.
HVAC Zoning System Cost
The cost of an HVAC zoning system depends on:
- The number of zones
- Number of dampers
- Whether it is an existing or New HVAC system
On average, an HVAC zoning system costs between $1700 and $5000 with the national average being $3100. Adding a second zone to an existing HVAC system costs between $1700 and $3000 and another $300 to $500 for every additional zone.
- A 2-zone HVAC zoning system will cost between $1700 and $2800
- A 3-zone HVAC zoning system will cost between $2500 and $3500
- A 4-zone HVAC zoning system will cost between $2500 and $4500
And that is everything about HVAC zoning systems. I hope that this guide was helpful and that it answered all the questions that you had.