Heating with natural gas is effective and efficient. The heat exchanger is a key part of your natural gas furnace since this is the mechanism that transfers the heat from combustion to your home. If the heat exchanger cracks, problems will occur. The following are things to watch for.

1. Odd Odors

A cracked heat exchanger will produce eye-wateringly bad fumes. These fumes will have a distinct chemical smell, similar to formaldehyde. You will likely smell them most strongly near the furnace, although they may travel to other parts of the home via the ducts. The odor will also be present mainly when the furnace is actually running. If you pick up this odor, turn off the furnace until you can have it repaired.

2. Soot Buildup

When the exchanger is cracked, it can't burn the fuel efficiently, so a lot of soot will be produced. This soot will build up on the surfaces inside the furnace. You may see it if you remove the access panel and take a peek. In severe cases, the soot may also start to appear on the outside of the furnace, particularly in the area nearest to the burner.

3. Condensation Issues

Condensation can form when the heat exchanger cracks as a result of incomplete combustion. The moisture doesn't evaporate as it should and instead condensates inside the furnace. You may notice moisture around the furnace or on the side of the device. Rust may also be present.

4. Burner Flame Changes

A burner flame or pilot light should burn as a steady blue flame. There should be no flickering or color changes. If the light is burning any other color or flickering, then you may have a cracked heat exchanger. The reason the flame is changing colors and flickering is that it can't maintain a steady temperature because of the damage to the heat exchanger. Turn off the furnace and schedule a repair as soon as possible.

5. Physical Illness

Carbon monoxide leaks can occur when the heat exchanger cracks and no longer burns off the fuel cleanly and completely. You may suffer from headaches, nausea, and other symptoms reminiscent of the flu. Continuing to breathe these fumes can be deadly, so you need to shut down the furnace immediately and open a window. Schedule a furnace repair and install a carbon monoxide alarm to help ensure future safety.

Contact a residential heating repair service immediately if you suspect issues with your heat exchanger.