Sage-Tips

How do I know if my furnace heat exchanger is bad?

Six Signs Your Furnace Heat Exchanger May be Cracked

1. Strange smells. A malfunctioning heat exchanger will often create an unpleasant and strong odor that smells similar to formaldehyde.
2. Soot Build-up.
3. Corrosion & Cracks.
4. Change in the flame appearance.
5. Audible Sounds.
6. Presence of Carbon Monoxide.

How do you test a heat exchanger for leaks?

Evidence of smoke on the exterior of the heat exchanger indicates leakage. Using a smoke puffer you can fill the burner chamber with smoke. Then turn the blower on. If the smoke sprays out and away from the burner opening you have a good indication of a leak in the heat exchanger.

What happens when heat exchanger fails?

The problem is that all heat exchangers will eventually fail, developing holes or cracks that allow those poisonous gases to leak out and contaminate your home’s air. These leaks can be extremely dangerous, even deadly. In fact, cracked heat exchangers are one of the major causes of carbon monoxide poisoning in homes.

How does a heat exchanger crack?

What is the cause of heat exchanger cracks? Overheating causes nearly all premature heat exchanger cracks. When a furnace cannot get enough airflow, the heat exchanger overheats and suffers excess stress from expansion and contraction. Over time, the heat stress causes cracks near weak areas such as bends or welds.

How often do heat exchangers crack?

The wear and tear of years on your furnace will naturally lead to cracks over time. If your furnace is aging, then it may be a good idea for you to check the age of its heat exchanger. Heat exchangers last from 15-18 years, so if your heat exchanger is aging, it may be time to replace it.

How long should a heat exchanger last?

In most cases, the heat exchanger determines how long your furnace will last. The heat exchanger is responsible for heating the air that circulates through your home in the winter. Heat exchangers usually last about 15 years. If you invest in maintenance, yours might even last 20.

How do you check a leak in a shell and tube heat exchanger?

Simply attach the unit to a water supply and note the leaking tube. 2). For smaller leaks, it may be necessary to submerge the heat exchanger under water and pressurize it with air at 50 psig maximum. Leaks can then be located by the “bubble trail.”

How does a heat exchanger get blocked?

Just like limescale build-up, central heating sludge building up in the heat exchanger will cause a boiler lockout. Essentially, bits of the heating sludge are restricting water flow. The heated water isn’t travelling around the system as quickly as it should be due to the blockage.

How often do heat exchangers fail?

A gas furnace heat exchanger should last a good 10-20 years, but it will eventually fail. That’s because of the way your furnace works. Metal expands when it’s heated and contracts when it cools. Over time, the cycle of expansion and contraction can cause metal fatigue.

Where do furnace heat exchangers crack?

When a furnace cannot get enough airflow, the heat exchanger overheats and suffers excess stress from expansion and contraction. Over time, the heat stress causes cracks near weak areas such as bends or welds. The most common cause of an overheated heat exchanger is as simple as a dirty air filter.

If you notice water around your furnace, abnormal smells, or black soot buildup, these are all warning signs that will let you know if your furnace heat exchanger has gone bad. Essentially, when your furnace heat exchanger has a crack it has gone bad.

Can you repair a cracked heat exchanger?

If your heat exchanger has gone bad, you have two options: replace the heat exchanger or replace the furnace. If it is available, the best way to repair a cracked heat exchanger is to remove the damaged cell and replace it. However, it is possible that other parts and controls in the furnace may also be in need of replacement at this point.

What does a heat exchanger do on a furnace?

The heat exchanger plays the integral role of shielding toxic “flue gases” (the gas and combustion fumes) from entering the blower, which distributes warm air through the ducts and vents of your home.

Should I replace the heat exchanger or the whole unit?

If you only replace the part, you may end up needing to replace it down the line anyway. It will be cheaper to replace it once rather than replace the whole unit as well as the heat exchanger. Although all heat exchangers fail eventually due to metal fatigue, most heat exchangers can last anywhere from 10-20 years. This is a long time!