The heat exchanger is the core of a home heating system. Whether it is a furnace or boiler, the heat exchanger is one part of the unit that cannot be ignored in regards to maintenance and efficiency. To do so may be deadly. So whether your unit has recently been diagnosed with a bad heat exchanger, or if you are just curious as to what your heat exchanger does, hopefully this will clarify your understanding of this vital component to your heating system.
For starters
What is a heat exchanger? In a furnace or boiler, gas is injected into the system where it travels to the burners to be ignited. The heat created by the ignition is transferred to the heat exchanger. A heat exchanger has two sides. For both a furnace and a boiler there is a fire side. This is the side directly in contact with the burners. Here, the heat exchanger is heated, and then it begins to distribute the heat to the other side. This side is in contact with the air, or water in the case of a boiler. The heated air, or water, is then sent throughout the home, while the toxic combustion products are safely directed outside the home.
The AFUE
The heat exchanger plays a big role in the efficiency of the unit. Every unit is required to meet a certain Annual Fuel Utilization Efficiency rating, AFUE, that is set by the government. This is a percentage rating based on the annual amount of heat created by the unit to warm your home compared to the annual amount of gas used by the unit. The higher the percentage, the more efficient the unit. The more efficient the unit the more money you could potentially save. The efficiency of the heat exchanger helps determine how much of the gas the unit is actually turning into heat for the home. If your heat exchanger is in poor condition, chances are your unit isn’t meeting its highest efficiency.
In order to ensure that the unit is running in optimal condition, it is important to have the unit cleaned and tuned up yearly. This will ensure that any potential issues are caught early on before they lead to devastating damage to the unit. Damage to a heat exchanger can include rust, corrosion, cracks, holes, clogs and leaks. These may sound like simple cosmetic issues, but in reality these can lead to some very serious consequences.
Problems?
A furnace that has been diagnosed with a bad heat exchanger will be shut down and deemed nonoperational by any licensed service tech. A heat exchanger with a hole or crack allows the unit to leak combustion gases into the air that is being heated. This air is then pumped throughout the home, which releases the gases into your air supply. The most toxic of these gases is CO or carbon monoxide. If carbon monoxide is allowed to build up in the home, it can potentially kill anyone who is breathing it in. However, consequences like this can be avoided.
What should you do?
Besides doing yearly maintenance, there are a couple other checks homeowners can make. To prevent clogging, the unit needs to be cleaned to prevent a soot buildup on the fire side of the heat exchanger. To prevent rust and corrosion, homeowners should make sure that the unit is housed in a dry environment. Damp or moist conditions can speed the rate of rust accumulation on the heat exchanger. For boiler systems specifically, homeowners should not drain the unit during the summer months or flush the system yearly. When the system is emptied, the heat exchanger, and the entire unit, is exposed to fresh oxygen which speeds the rate of rust development. Water should be left in the system year after year. When it comes to cracks and leaks, boilers can be checked by simply looking for any leaking water coming off the main unit. For furnaces things are not as easy. Most heat exchangers are hidden from view by the burners, and therefore are best examined by a trained professional. They may use mirrors to see in smaller places, or the burners may be removed in order to pull the heat exchanger out for a more thorough check. Unfortunately a damaged heat exchanger means that the unit is going to have to be replaced. There are some cases where it is possible to just replace the heat exchanger, but this is usually done when the defect in the heat exchanger is caused by a manufacturing flaw. Otherwise, this repair can often be as costly as a replacement unit.
The heat exchanger is of vital importance to the safety and efficiency of the unit. Regular checks and maintenance are crucial to keeping it in working order. If neglected, it may cost you more then just the cost of a new unit.
Great post! I like the blog!