Your HVAC system is only designed to last so long, especially if you don't perform routine maintenance. According to This Old House, three months is the ideal schedule for changing your air filter. Changing filters is only one aspect of maintenance, however. If you have old heating and air, watch out for these five signs that it's time to replace your HVAC.

1. High Energy Bills

It's no secret that heating and air can account for a significant portion of your energy bill. However, your monthly bill shouldn't change too much when the temperature doesn't change. If your winter heating bill or summer cooling bill is suddenly much higher than normal, it might be time for an upgrade.

2. Noises

Your HVAC system should make a little noise when it's running, but it shouldn't be especially loud or make any strange sounds. If you hear a squealing, rattling, grinding, scraping, or vibrating noise, you might have a problem with your HVAC system. Call a professional if you hear anything out of the ordinary.

3. Smells

Bad odors can also be a sign that you have HVAC issues. If you notice a strange smell, especially if that smell is only present when your heating or cooling kicks on, you should have an HVAC technician check out your ducts and HVAC system to figure out what's wrong. The sooner it's looked at, the better.

4. Comfort Issues

Homeowners spend a lot of money to keep their homes comfortable, so that's the least you can expect. If you're having a tough time keeping your home at a comfortable temperature even when you're cranking the heat or AC, you might have an airflow problem. The unit may need to be replaced altogether.

5. Age

As your furnace and AC get older, they become more prone to problems. ACs and furnaces are only expected to last a number of years, so you might want to have your HVAC system inspected if it's getting older. An HVAC technician can help you decide if you need simple repairs or if it's time to upgrade your HVAC system.

Keeping your home at a comfortable temperature is key during the summer and winter. As a homeowner, it's up to you to keep an eye out for problems, so you know when it's time to call a heating and air company. If you need HVAC maintenance or upgrades, call C & G Heating and Air, Inc to get a technician out to your house as soon as possible.