Deep Cold? Make Sure You Check These Furnace Issues

Stay warm in the midst of a deep freeze by checking these furnace issues.

When a bout of subzero weather swoops in, make sure you’re checking things with your furnace to prevent problems. Here are a few furnace issues you need to take a look at.

Furnace intake and exhaustFamily Handyman

Check the Intake and Exhaust Pipes

Newer high-efficiency furnaces will shut off if something like a bird or ice buildup blocks either the fresh-air pipe or the exhaust pipe. You’ll need to go outside and peek inside the pipes to see. Sometimes a critter can get lodged in the pipe all the way back to the furnace and you won’t be able to see it without taking the pipe apart, a job best left to a pro.

Clean and dirty furnace filters, changing furnace filterFamily Handyman

Furnace filters

A clogged furnace filter can cause a furnace to shut off. Dirty filters are the most common cause of furnace problems. Dust and dirt restrict airflow—and if the filter gets too clogged, the heat exchanger will overheat and shut off too quickly, and your house won’t warm up. If the blower is running but no heat is coming out, replace the filter. A dirty filter also causes soot buildup on the heat exchanger, reducing the efficiency of the furnace and shortening its life.

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Flush Out Drain Lines

High-efficiency furnaces can drain off several gallons of water a day in heating season. If the drain lines become restricted by sediment or mold growth, the furnace will shut down. If the drain hose looks dirty, remove the hose, fill it with a mixture of bleach and water (25 percent bleach), then flush it after several minutes.

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Look For Blocked or Leaky Ducts That Can Restrict Airflow

If your furnace comes on but one or two rooms are cold, first make sure all the room registers are open. Then examine any ductwork you can get access to and look for gaps between sections or branching points. Seal any gaps between sections of duct with special metal duct tape. Don’t use standard cloth duct tape—it quickly deteriorates, and it may also cause ducts to leak if it was used to seal sections in the past.

Also check for handles protruding from the ductwork. These are dampers or air conditioner bypasses—make sure they’re open. Learn more about working with round duct work here.