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2 Aspects of High-Efficiency Furnace Maintenance

Fixing furnace
Furnace technology has advanced a lot in recent decades, and many manufacturers have developed new ways to boost performance while lowering overall costs. For the best results, homeowners should strongly consider investing in a high-efficiency furnace, also sometimes referred to as a condensing furnace. A high-efficiency furnace allows you to maximize the amount of heat produced from your fuel.

Of course, homeowners should realize that the enhanced abilities of a high-efficiency furnace come at a higher maintenance cost. If you would like to learn more about what it takes to keep a high-efficiency furnace running at peak capacity, keep reading. This article outlines two key aspects of high-efficiency furnace maintenance.

1. Combustion Analysis

Unlike standard furnaces, high-efficiency units contain not one, but two heat exchangers. This second heat exchanger allows the furnace to extract even more heat from the combustion air. As a result, a highefficiency furnace can effectively capture 90 percent or more of the heat generated inside of the combustion chamber.

Yet homeowners should never assume that their high-efficiency furnace will continue to operate at such rarified levels as time goes on. If not all of the fuel's heat gets released during combustion, no amount of heat exchangers can make up for it. Historically, contractors had relatively few ways to measure just how efficiently combustion proceeded. Today, however, technicians can quantify efficiency using the technique known as combustion analysis.

Combustion analysis uses a special tool to measure the levels of certain compounds in your furnace's exhaust gas. If the levels of things like oxygen or carbon monoxide remain too high, it means that your furnace needs adjusting.

Different furnaces have different thresholds for such substances. Keeping the levels of combustion byproducts within specified limits ensures that your furnace lives up to its promises of efficiency. Correcting abnormal combustion analysis results usually involves tweaking the air-to-fuel ratio inside of your furnace.

2. Temperature Rise Measurement

All furnaces come with a rating pertaining to their ideal temperature rise. Manufacturers generally express this rating as a thirty-degree range. For instance, a particular furnace may have a permissible temperature rise of 30 to 60 degrees, or 40 to 70 degrees. The first number expresses the lowest allowable temperature rise, while the second expresses the highest.

Temperature rise has to do with the difference between the return air and the supply air - in other words, the air as it flows back to your furnace from the rooms of your home, and the air as it leaves your furnace. Technicians must periodically test a system to ensure that the temperature rise remains within the prescribed limits.

If the temperature rise drops below the lower threshold, you may notice that the air coming out of your registers feels unusually cool. In that case, the furnace simply isn't generating enough heat to transfer to your home. In some cases, this issue can even lead to condensation forming inside of the primary heat exchanger, thus shortening its lifespan.  

When the temperature rise exceeds the upper limit, even more serious problems ensue. At this point, your furnace generates more heat than it should. In many cases, the excessive heat level triggers the limit control switch to shut the furnace down entirely. While this protects your system against overheating, it also means that your home will not receive heated air.

Ideally, the measured temperature rise of a system should fall somewhere in the middle of the manufacturer's range. A professional HVAC technician knows just how to determine the temperature rise of a high-efficiency furnace. For more information about having this vital service performed on your furnace, please contact our experts at Riverside Heating & Air Conditioning.