Why Condensing Furnaces Are So Energy Efficient

May 10, 2022Back to blog
What is a condensing furnace

If you’re planning to purchase a new heating system, you will be required to invest in either a standard gas furnace or a high-efficiency condensing furnace. Due to their ability to offer energy savings without sacrificing your comfort, these condensing furnaces are typically the go-to option for most homeowners today.

But why is this so? Why are condensing furnaces so efficient? These are the questions that we’ll be addressing in the following article. Keep reading to learn more.

What is a condensing furnace?

Old furnaces are built with only one heat exchanger. This results in a certain amount of heat loss during the combustion process. Condensing furnaces are equipped with a second heat exchanger that is capable of extracting extra heat from the water vapor that would normally be vented out of your home.

This allows the system to make better use of available energy, significantly reducing its operating costs. Of course, this isn’t the only reason why condensing furnaces are such a popular trend in the HVAC industry.

They also have other excellent features, including:

Electronic ignition

Traditional furnaces rely on a conventional pilot light for startup and continued operation. This means that your furnace is constantly consuming a small amount of fuel just to keep the pilot light lit. Adding up this fuel usage over the course of months will result in higher long-term costs.

Instead of a pilot light, condensing furnaces use electronic ignition which turns on only when it is needed. Electronic ignition systems offer better reliability than traditional pilot systems and eliminate fuel wastes.

Modulating burner gas valve

Another feature where condensing furnaces are more efficient than traditional ones is burner gas valves. A conventional furnace uses a burner gas valve with two states: on and off. This means that single-stage burner gas valves operate at 100 percent capacity when activated. Using a single-stage burner gas valve is impractical when it comes to moderating the burner flame for improved energy efficiency.

A lot of furnaces are being upgraded by switching to a dual-stage feature to solve single-stage burner gas valves’ inefficiency. Dual-stage burner gas valves provide high and low settings with use of electronic controls. These controls give dual-stage burner gas valves a higher level of flexibility than single-stage ones.

Condensing furnaces use modulating burner gas valves that offer an even greater range of operation. These gas valves can increase or decrease their output in single-percent increments. These fine-tuned controls help eliminate drastic temperature swings while boosting the furnace’s overall efficiency.

Variable-speed blower motor

Standard furnaces have permanent split capacitors or PSC blower motors for air circulation. Without variable controls, it is nearly impossible to moderate indoor temperatures on standard furnaces without the blower motor going on and off repeatedly.

High-efficiency condensing furnaces use electronically commutated motors or ECM that can operate at a variety of speeds that are energy efficient. Unlike PSC motors that run at full capacity, ECMs can adapt to your heating demands.

Variable-speed blower motors help condensing furnaces achieve excellent efficiency ratings. These motors work even at extremely low RPMs to provide quiet, continuous air circulation throughout a home.

Sealed combustion chamber

Traditional furnaces draw air from indoor spaces with the use of combustion chambers. It leaves the combustion chamber exposed to the rest of the home. This type of design results in combustion gasses being drawn out of the exhaust flue under negative pressure and returned inside the home.

In condensing furnaces, sealed combustion chambers are used that are completely separate from indoor spaces. The combustion chamber of condensed furnaces receives air supply from the outside of the house. Sealed combustion chambers are safer and more efficient due to reduced heat loss.

Secondary heat exchanger

On a conventional furnace, the hot exhaust gasses generated through the combustion process travel through the heat exchanger. This series of metal tubes pass the heat between the passing exhaust gasses and the circulating air that flows over the device. Any leftover heat is simply carried away into the flue and vented outdoors.

Condensing furnaces prevent excess heat by circulating exhaust gasses through another heat exchanger to prevent heat waste. Excess heat is collected by the secondary heat exchanger and prevents it from passing through the outdoor vents, boosting the furnace’s efficiency.

With traditional furnaces where hot exhaust gasses generated through the combustion process travel through the heat exchanger. These metal tubes pass the heat between the passing exhaust gasses and the circulating air that flows over the device. Any excess heat travels into the flue and is released outside your home.

Heat recovery ventilator

Heat Recovery Ventilator or HRV collects fresh outdoor air into the furnace and pulls heat from stale indoor air with the use of a built-in air-to-air heat exchanger. The extracted heat is then used to pre-heat the incoming air before it reaches the furnace.

Tightly sealed homes often use HRVs because there aren’t any cracks or crevices for fresh outdoor air to be pulled through. Using an HRV also improves a condensing furnace’s overall energy efficiency.

Why Condensing Furnaces Are So Energy Efficient

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