Adding central air conditioning is a common upgrade for older homes. In many cases, installing new ductwork can be the most challenging and expensive part of this process, but it's not the only concern. Since central air conditioning systems were not common in homes until relatively recently, many older houses lack the necessary electrical infrastructure to support them.

Fortunately, upgrading an older home to support central air conditioning usually isn't hard, but it will require a trained electrician or an HVAC contractor with electrical experience. If you're about to make this upgrade, here are three critical considerations you'll need to keep in mind as you discuss your options with contractors.

1. Service Panel Size

Your electrical service effectively determines the maximum capacity of your service panel to support circuits and appliances. Modern homes typically use 150-amp or 200-amp service, but older homes may use much smaller service panels. These panels were sufficient for the limited number of appliances in older homes, but they can be a stretch for modern requirements.

If you don't know your home's electrical capacity, you can usually check the size of the main breaker or fuse in your service panel. Contact your electrical company or have an electrician check for you when in doubt. Since central air conditioners require a dedicated circuit, you may need to perform a service panel upgrade if your home uses an older and smaller panel.

2. Fuse to Breaker Conversion

If your home is old enough, you may have a fuse box instead of a breaker panel. While fuses work perfectly fine, there are some reasons to consider conversion if you add new HVAC equipment. In particular, many older fuse boxes may not easily support the addition of 240-volt circuits, which central air conditioners typically require.

In these cases, your options may include adding a sub-panel or replacing your existing fuse box with a breaker panel. While the former option is usually cheaper, the latter can provide a worthwhile upgrade to your home's electrical system while supporting your new HVAC equipment. The best choice for your case will depend mostly on your budget.

3. Low-Voltage Wiring

Low-voltage wiring links your HVAC system to your thermostats. If your home has at least one thermostat, you likely already have some low-voltage wiring. However, older homes may not have the wiring necessary to support cooling or the common wire necessary for modern thermostats and smart equipment. You also may want to add multiple zones, which will require wiring for extra thermostats.

Although adding new low-voltage wiring may be a fairly involved process, it's a step that will help to future-proof your home and add support for more advanced HVAC control equipment.

For help preparing your home for an HVAC upgrade, contact a residential electrical service in your area.