If you have a car or other gasoline-powered equipment, a periodic tune-up makes sense. Carburetors can fall out of adjustment and burn too much fuel, stall because they aren’t getting enough fuel, or fail to start because of worn spark plugs.

With furnaces, however, one local HVAC contractor I consulted was reluctant to use the word “tune-up,” preferring to say he only did maintenance. Another local contractor was OK with the terminology but wouldn’t tell me what was involved, because he considered it a trade secret. Really?

Fortunately, New York-based Mark Fisher, general manager of HomeServe Energy Services, and Texas-based Mark Woodruff, an engineer and senior product manager at Trane Residential, were happy to help. It’s information every homeowner needs, because a poorly maintained furnace breaks down more often than you might expect, and repairs are not cheap.

What Is a Furnace Tuneup?

In general, it’s an inspection to ensure the furnace system runs efficiently and burns as little fuel as possible, keeping energy costs down.

Fisher provided a detailed checklist that he says takes about an hour:

• Check safety systems and controls.
• Check/adjust thermostats.
• Check/clean burners.
• Check/clean pilot.
• Check/clean gauge and flush low water cut-off.
• Check filters and belts.
• Check flue pipe and chimney draft.
• Check oil in motors and pumps.
• Check/clean blower assembly.
• Check condensate line, if applicable.

No industry standard exists for furnace tune-ups, so some contractors may spend more time on it than others. Be sure to obtain and review a list of work to be performed before signing anything.

Can You DIY a Furnace Tuneup?

Sometimes. Certain tasks are simple enough for homeowners to complete themselves.

You can clean the blower assembly, generally found behind a removable panel, by dusting it with a rag or blowing compressed air on it. If you have a high-efficiency furnace that converts exhaust gases into liquid condensate, you can check the drain pan for standing water and clean out the condensate drain with a wet/dry vacuum.

Most other tasks call for special testing equipment and a thorough understanding of how furnaces work. There’s nothing to stop an enterprising homeowner from obtaining testing equipment and studying their owner’s manual. But in most cases, it’s better to leave it to a pro.

One item Woodruff says homeowners should do frequently is replacing the furnace air filter. “Dirty filters restrict air flow, making your HVAC system work harder and reducing its efficiency,” he says. Replacing it every three months is a good rule of thumb.

How Often Is a Furnace Tuneup Necessary?

The most common answer is once a year, but not all homeowners follow that. A 2023 HomeServe survey found 21% of respondents never had their HVAC systems tuned up, and 18% never changed their filters, according to Fisher.

“Heating and air conditioning systems are the home systems most likely to break down, with 28% of homeowners reporting a repair in the past 12 months,” he says.

It comes down to how well you want your furnace to function. A unit that runs inefficiently wastes fuel and is more likely to break down, creating an expensive emergency. “What might seem like a minor issue now could become an expensive one later if you don’t address it,” Woodruff says.

Keeping to an annual tune-up schedule makes good financial sense for another reason. It’s recommended by most manufacturers, and warranties usually stipulate repairs aren’t covered unless you follow it.

How Much Does a Furnace Tuneup Cost?

According to Fisher, the average cost is around $150. If the maintenance visit turns up anything that needs special attention, the cost may be a little higher. But it’s still a bargain, considering the average cost of a repair is more like $450.

About the Experts

• Mike Fisher is general manager of energy services at HomeServe USA. The company issues home repair insurance policies nationwide.
• Mark Woodruff is an engineer and senior product manager for Trane Residential.