Your furnace and air conditioner should not be on the same circuit breaker, even if they are part of the same HVAC system.
Although the terms “HVAC” and “air conditioner” (AC) are used interchangeably, the functions and setup of these systems can vary drastically.
Though the air conditioner and furnace of your home both form part of your larger HVAC system, it is important that each of them are set up on their own circuit breaker.
What is the difference between an HVAC system and an AC unit?
When it comes to the heating and cooling systems in your house, electricians and contractors often use the different terms interchangeably.
An HVAC system which controls the heating, ventilation, and air conditioning of your house, encompasses many varying elements such as a heat pump, furnace, air conditioning unit, and more. However, an air conditioner is only responsible for cooling air in this system.
This means that you can have an air conditioner on its own in your home, or you can have an air conditioner as part of a larger system that also heats and ventilates your house. This system network is referred to as your HVAC system.
Is a furnace on the same circuit breaker as an air conditioner?
Since heating and cooling systems vary from house to house, the setup for these systems can also differ, depending on whether you have a complete HVAC system or you installed an air conditioner and then later added a furnace.
If you have a furnace and an air conditioning unit that is built in as part of an HVAC unit, this kind of system is usually installed as a single unit, which will mean that they are on the same circuit.
However, in some cases, professional HVAC installers may install different components of this system on dissimilar circuits.
The most common type of system for a home that has both a furnace and an air conditioner is one where you already have an air conditioner, and you want to add the rest of the HVAC system in addition to your air conditioner at a later stage.
In this case, in order for your building to abide by code, the air conditioner and the furnace each need to be on their own circuit.
This is the safe, modern way of doing things, since the air conditioner and furnace both draw a lot of power and it is better to have each of them on their own circuit, even though they may still share other components. This also ensures that your house is up to code.
Why should you have separate circuits for your furnace and air conditioner?
It is a good idea to have your furnace and air conditioner(s) on separate circuits, as this will ensure that you are not overtaxing a circuit by running these two units on it at the same time.
This is a particularly good idea if your air conditioning unit requires between 110 and 120 volts, and requires seven amps or more to operate, since these demands will place considerable strain on your system on its own, that’s besides the additional strain on your electrical board by also having a furnace connected to the same circuit.
Having your air conditioner and furnace on their own circuits will also help protect your electrical equipment by ensuring that your system does not trip or shut off unexpectedly, even when there is an issue with either of the units. This ensures that your house is safer overall.
What does the National Electrical Code require?
Houses in which the HVAC system is all connected as one unit on the same circuit are likely older houses, since newer houses have to be up to code.
The National Electrical Code states that a furnace should have its own dedicated circuit, which is to say that the circuit cannot supply power to anything other than the furnace.
This means that neither you nor a professional are permitted to install an air conditioner on the same circuit, as the furnace and the air conditioner both need their own separate circuits for your house to abide by national code.
What can the furnace and air conditioner share?
Although the furnace and the air conditioner each need to have their own circuit, it is common for these appliances to share the same filter and ductwork in your home.
However, this system is unlikely to share any other components, as these units are separate from each other and consist of an air conditioner that is an outside unit, responsible for cooling air with chilled refrigerant, and an inside unit through which the furnace generates heat through coils and fans.