A furnace is a vital component in virtually every home heating system across the country. Many people may not be aware that a furnace can cause a house fire if the conditions allow it. According to data released by FEMA, heating appliances were the second highest cause of building fires in homes during 2014. In this article, we will look at furnace fires in more detail, examine three main reasons why they occur and look at some ways to prevent them.
A Brief Primer on Furnace Fires
As the weather starts to get colder, many people turn on their furnaces for the first time in months and expect them to work without any attention at all. A furnace is a complex piece of equipment, and it needs regular maintenance to work correctly. This should be carried out early in fall before the weather gets too cold and the demand for HVAC engineers increases. A heating system that maintained annually will have better efficiency, and the heating bills will be lowered. There are also safety concerns that need to be understood to reduce the chances of a furnace fire. Below we will look at the three leading causes of a furnace fire that regular maintenance can help to avoid.
- A Blocked Air Filter
Every home furnace will contain an air filter, which is vital for the heating system to work correctly. The air filter has two main roles that it plays in making sure that the furnace work as intended. First, the air filter will make sure that the air coming into the atmosphere is free from a variety of unwanted materials, such as dirt, dust, pollen and pet hair. Second, by removing these materials, the air filter is preventing them from causing damage to internal components in the furnace.
Over time, the air filter can become blocked and clogged with this debris. When the air filter is blocked the airflow will become compromised, and the furnace will be forced to work hard to draw fresh air into the heating system. Eventually, the furnace could work so hard that it can overheat and the blower motor may even catch fire.
For this reason, it’s a good idea to change the air filter on a regular basis. Changing the filter every month should be adequate for most homes, but if you have pets, it may need to be changed more often.
- The Gas Pressure is too High
A furnace needs a combination of gas and air to generate the necessary combustion to create efficient heating. A clean and clear air filter will ensure that the furnace can get adequate amounts of the air that it needs. But, the gas also has to flow into the combustion chamber in the furnace at a specific pressure.
The gas pressure needs to regulated to avoid problems relating to an incorrect mixture of gas and air. If the gas pressure is too low, it could lead to condensation in the heat exchanger that may cause corrosion issues. If the gas pressure is too high, it will lead to an over production of heat inside the furnace.
The furnace has internal components that have a strict tolerance to certain levels of heat. If this is exceeded, these components are at risk from setting on fire. As an example: A very high internal furnace temperature could make the soot in the walls of the heat exchanger combustible, and a fire could start. These types of furnace fires are very fierce, and they can quickly spread out of the furnace and into other parts of the heating system.
- A Cracked Heat Exchanger
The heat exchanger in your furnace is needed to allow the heat to transfer into the air that is then forced into your home through the ducts and vents. At the same time, any toxic gases produced during the combustion process are held safely in the heat exchanger and later vented out of the home via the flue pipe.
A heat exchanger is a hard working component, and over time the repeated cycles of expansion and contraction due to heating and cooling will take a toll. The metal is placed under a great deal of stress, and eventually, cracks will begin to form. These cracks may only be noticeable when the heat exchanger is heated up, and they will close up as it cools down again.
These cracks are dangerous; they allow toxic gases such as carbon monoxide to escape into your home. These gases can pose a serious health risk, and they are also flammable. The presence of the gases even is smaller quantities can significantly increase the chances of a house fire.
The Flame Rollout
One of the most dangerous events that can occur because of the causes detailed above is a flame rollout. This is when the flames escape from a closed combustion area and then roll into flammable materials that are located nearby. There are two main indicators to look for; they are a discolored furnace cover and singed exterior furnace components.
A flame rollout occurs when there isn’t enough oxygen present to feed the combustion process in the furnace. As we mentioned above the furnace requires both gas and air to create heat, but they have to be present in specific quantities. If there isn’t enough ventilation to provide adequate amounts of oxygen the furnace will produce flames that can roll out to get the oxygen from outside the furnace.
This situation is extremely dangerous, but it can be prevented by following these four simple tips:
- Change the air filter regularly.
- Keep the furnace flue clear of obstructions.
- Consider installing a rollout switch safety device.
- Schedule annual maintenance for your furnace.
If you follow these four simple tips, a flame rollout is far less likely to happen. It’s also essential to carry out an annual maintenance checkup at the start of each heating season for other reasons. A well maintained heating system is less likely to fail when you need it most, and minor issues can be identified and fixed before they turn into more significant problems. The energy efficiency will also be maximized, which will save you money on your winter heating bills.