Even when a major furnace component is covered, the labor bill can still climb into the thousands.

A homeowner with a 15-year-old furnace believed an HVAC company was pushing them toward a full replacement after diagnosing a failed heat exchanger.

After finding out the part was still under warranty, they discovered the labor estimate alone came to $1,800. The homeowner then shared the quote on Reddit's r/AskHVAC and asked, "Does that sound right?"

What people said

According to the Reddit thread, the service company told the homeowner they could either pay $1,800 to replace the heat exchanger or install a brand-new furnace.

HVAC workers responding to the post said the quote sounded normal for an in-warranty heat exchanger replacement. One commenter wrote, "Yeah I'd say that's pretty close. I'd say it averages $1,200 - $2,000 to replace an In warranty heat exchanger."

Another said, "$1,800 is pretty much bang on for the labor portion to replace a heat exchanger."

A third commenter estimated labor at about $1,600 for an 80% furnace and $2,100 for a high-efficiency heat exchanger, adding that "most guys are going to spend 4 to 6 hours doing a heat exchanger."

The situation shows that even when a major furnace part is covered, labor costs can still reach four figures, while replacing the entire system may also open the door to lower energy bills each month.

Palmetto says it can help homeowners compare HVAC options and cut energy costs with newer, more efficient HVAC systems and heat pumps. It also says it has a network of vetted technicians that homeowners can turn to when an aging unit suddenly becomes a repair-or-replace decision.

The homeowner's experience is a reminder to check warranty coverage before choosing between repair and replacement. In this case, the original poster said the heat exchanger was still covered, even though the company did not mention that right away when presenting the repair-or-replace options.

If a replacement still makes more financial sense, Palmetto says its Comfort Plan includes $0-down options that can reduce heating and cooling costs by as much as 50%. Palmetto Comfort Plans also include 12 years of free maintenance, which can help homeowners prepare for surprise repair costs on older furnaces.

More to know

These cases point to the same mix of warranty confusion and repair sticker shock that can come with a major HVAC failure.

• A first-time homeowner still owed $2,300 after a 15-month-old HVAC failed under warranty.

• A landlord questioned a $1,400 bill after a 'warranty coil' charge arrived without approval.

• One homeowner was shown a '10-year warranty' in writing, then told it expired.