Variable Speed Furnace – How It Works and What Its Advantages Are

If you are in the market for a furnace repair installation or a new furance, you may have come across a variable speed furnace. This is a furnace that uses innovative technology to offer high energy efficiency levels as well as optimal comfort. In addition, a variable fan speed furnace minimizes scenarios of inconsistent temperatures. However, if you are like most people, the question you want to be answered is this: are variable speed furnaces better? This post looks at how these furnaces work and why they are better.

What Is a Variable Speed Furnace?

Variable-speed furnaces contain an electronically commutated motor (ECM) blower motor. An ECM is a DC motor with a built-in inverter and a magnet rotor. It delivers better energy efficiency than an AC motor. The ECM is the feature that helps variable speed furnaces to operate at a much higher efficiency level.

Are variable speed furnaces more expensive? The answer is both yes and no. While the initial cost is higher than that of a traditional furnace, ECMs are energy-efficient, low-maintenance and significantly cut operating costs. Payback on a variable speed furnace is 4 to 5 years.

How Does Variable Speed Furnace Work?

Unlike traditional furnaces that run at a single speed, a variable speed furnace blower motor runs at a variety of speeds. The speeds are what control cooling airflow and heating.

The furnace has a pre-programmed controller which monitors incoming data from the HVAC system. The motor starts at a slow speed and increases speed to attain the set temperatures on the thermostat. Once the thermostat settings are reached, the controller slows down the blower enough to maintain the desired temperature.

Does a variable speed furnace run all the time? The answer is yes. Variable-speed furnaces don’t wait for temperatures in the house to drop for them to cycle back on. The variable fan speed furnace runs nonstop but has an output of 60% or less. It is the constant running that helps maintain steady temperatures throughout the day.

If your next question is does a variable speed furnace needs a special thermostat, the answer is yes. For you to be able to adjust the fan speeds as required to achieve maximum comfort, you may require a particular thermostat. These furnaces come with a smart thermostat that adjusts the blower motor automatically, among other things.

Advantages of Variable Speed Furnaces

With Variable Speed Furnace You Can Expect Better Humidity Control

Variable speed blowers operate constantly. This causes the air in the house to cycle through the humidifier often. As a result, you will notice better indoor humidity control with a variable speed furnace than with a traditional furnace. Better airflow control leads to better humidity and temperature balance.

Variable Speed Furnace Are Energy Efficient

Installing a furnace fitted with variable speed technology increases energy efficiency significantly. This is because single-speed furnaces operate at 100% when switched on, even to raise the temperatures by a degree. Variable-speed furnaces, on the other hand, are designed to adjust the output with precision. When you need to increase the temperatures, the variable speed heating system will not start at 100% but at a slower speed to increase the temperatures gradually. This helps eliminate the issue of ‘cold start’ feeling, which is common with one-speed heating systems. The Office of Energy Efficiency & Renewable Energy found that variable-speed motors operating continuously at half-speed used 75% less power than single-stage motors when moving the same air volume.

Variable Speed Furnaces Work Quieter

The fact that a variable speed motor does not start at 100% means the furnace has a quieter operation. It will ramp up speed slowly with no sudden ‘blast’ or ‘kick’ of air at startup. There is also less stress on the system, thus reducing the chances of breakdowns.

Variable Speed Motor Will Clean The Air At Home

The fan of a variable speed furnace is usually in constant operation. As a result, the motors will circulate the air in your home slowly and continuously. This allows air to go through the air filters several times. This helps capture more contaminants. This is unlike a single-speed furnace that starts running when the temperatures drop, which means the air is only cleaned when the furnace is on.

Can Variable Speed Furnaces Save Money in the Long Run?

Although the initial purchase price of a variable speed furnace is higher than that of a traditional furnace, variable speed furnaces will help you save more money in the long run. This is a fact that was confirmed by the Office of Energy Efficiency & Renewable Energy, as we mentioned earlier. Needless to say, when your home is using less energy, you will notice significant tangible savings on monthly utility bills.

A variable speed furnace is able to use less energy because it operates at several speeds and adapts to a home’s airflow requirements. The blower will work at the lowest speed and adjust to higher speeds when more airflow is required. For example, when your air filters are getting clogged, the speed of the motor will increase to compensate. Conversely, if you need to raise the temperatures by a degree, the motors will operate at a slower speed.

Thanks to the low energy consumption, the savings you get from a variable speed furnace will help you enjoy a payback period of about 4 to 5 years.

Variable Speed Furnace – Is It Worth It?

High-efficiency furnaces are those with a rating of 90% and above. What this means is that if a furnace is rated at 90%, it means that 10% of the energy used will be lost, whereas only 90% will become heat. Modern-day high-efficiency furnaces have a rating of up to 96%.

Away from the ratings, when considering energy consumption, you should not focus only on gas consumption but also on electrical consumption. For example, the blower is what determines how much electricity a furnace uses.

Standard furnaces use standard blower motors. This means the furnace only runs at a single speed. These motors provide sudden and noisy blasts of air when switched on. In addition, the motors are larger and not energy efficient.

This is where variable speed furnace motors excel. Variable-speed blower motors operate at a variety of speeds to control airflow precisely. These motors monitor data from the HVAC system and adjust the speeds accordingly to maintain the desired comfort levels. The motors ramp up speed gradually, thus reducing strain on the system. This results in fewer breakdowns on a variable speed furnace. It is also good to note that a variable speed furnace motor is 80 to 85 percent more energy-efficient than a standard furnace motor.

With these facts and advantages in mind, it is clear that upgrading to a variable speed furnace is worth it. So get in touch with AirMakers for help finding the right variable speed furnace. We are always happy to help.