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Our team at Save Home Heat Company has posted previously about variable-speed and variable-capacity forced air furnaces, close cousins that are equated with quieter, more comfortable, high efficiency home heating systems. One of the keys to their performance, which was actually introduced in the electrical industry over 40 years ago, is variable-speed motor technology. In the past decade-plus, variable-speed motors have had a big impact on the residential HVAC industry, and homeowners appreciate these advancements.

In this post, we’ll provide an overview of variable-speed fans that are crucial to the performance of high efficiency, enhanced performance furnaces, and we’ll also look at other products we install that incorporate variable-speed technology.

The key to a variable-speed fan’s performance is the ECM, which stands for “electrically commutated motor.” Regardless of being redundant, the term “ECM motor” is used routinely. While there are different types of ECM motors, the core function is essentially the same: An ECM motor incorporates a special electronic control that monitors system performance in real time, and automatically adjusts the motor’s speed upward or downward to operate as efficiently and effectively as possible.

An ECM motor plays an important role in the performance of not only certain high efficiency furnaces, but also in top-end boilers, virtually all tankless water heaters, and even certain models of AC and heat pump systems. Let’s look a little closer.

The most efficient and most comfortable forced air furnaces we offer, as well as the quietest and most comfortable mid-efficiency models we install, all rely on one or more variable-speed fans in their design. Variable-speed fans are a game changer when it comes to creating a more comfortable, quieter, heating experience. In forced air furnaces that are equipped with a variable-speed main blower, fan speeds are monitored and automatically adjusted during operation, to meet the exact and changing comfort needs of the home. The main blower often runs at lower speeds, and at the beginning and end of every heating cycle the fan slowly ramps up and down, so it’s not very noticeable when the furnace kicks in and shuts down.

In addition to more uniform comfort, variable-speed fans mean quieter operation throughout the house, and the Lennox furnaces we regularly install grade out as superior on noise level ratings.

Our flagship furnace line, Lennox Industries, is known for manufacturing the quietest and most efficient forced air furnaces, and those particular units are equipped with variable-speed fans. The variable-capacity (aka. variable-output), model SLP99V from Lennox, our most popular furnace, boasts an industry-leading 99% AFUE efficiency rating. In addition, the SLP99V also has a variable-speed exhaust fan, whose speed is precisely coordinated with the heat output of the furnace’s automatic, modulating gas valve.

In the SLP99V, gas and electrical consumption are the lowest achievable. According to Lennox, the SLP99V is “the quietest and most efficient furnace you can buy,” and consistent feedback from our customers seems to back up that claim.

Of note, there are variable-speed main blowers available in certain high efficiency, two-stage furnaces, as well, units which offer efficiency ratings in the 95% AFUE range – albeit with only two levels of heat output, as opposed to the variable-capacity unit which most of our customers prefer.

In addition to forced air furnaces, variable-speed technology is employed in other types of heating and cooling equipment that our team at Save Home Heat installs, including hot water based systems. Here’s a brief look at those hot water products:

Similar to variable-capacity forced air furnaces, our most efficient hot water boilers, from Triangle Tube and Burnham, also incorporate modulating gas valves, which produce just the amount of heat needed to do the job as efficiently, quietly, and as comfortably as possible. The exhaust fans on these types of boilers incorporate a variable-speed, ECM motor: Very quiet and electrically efficient removal of the gaseous products of combustion to the outdoors.

Variable-speed water circulator pumps may not be new to the industry, but they’ve steadily gained popularity in recent years. The reasons for this trend are straightforward: Variable-speed pumps, equipped with ECM motors, offer quieter, more even, and more electrically efficient performance. By adjusting the speed of the pump to meet the system’s needs, in real time, these pumps use less electricity and are a great match for virtually any type of boiler or hot water based heating system.

Virtually all gas-fired, residential tankless water heaters today come equipped with variable-speed fans to exhaust combustion gases to the outdoors. Much like the state-of-the-art furnaces and boilers discussed above, these water heaters also feature a self-adjusting, modulating gas valve, which produces only the amount of heat needed to do the job – keeping gas consumption at a minimum and achieving high efficiency ratings. Once again, the exhaust fan employs an ECM motor, resulting in quieter operation along with lower electrical consumption.

The quietest and most efficient central and ductless mini-split air conditioners and heat pumps we install all have one thing in common: variable-speed in their designs. Located in the outdoor unit, the compressor is the heart of a heat pump or air conditioner and it plays a crucial role in the refrigerant cycle that produces cooling and heating. In our most efficient heat pumps and AC systems, the variable-speed compressor that’s employed is considered to be a type of ECM motor, although quite different than the ones mentioned above. Lastly, the fan that’s installed in the outdoor unit in these systems, which exhausts heat to the outdoors, also has a variable-speed ECM motor.

So, just like our top-of-the-line furnaces, boilers, and tankless water heaters, our top-tier heat pumps and air conditioners are also variable-capacity systems, featuring the quietest, most efficient performance currently attainable.

Variable-speed technology has helped transform home comfort in many ways, resulting in more efficient, quieter, more comfortable options for home heating, cooling, and domestic hot water. If you have any questions about variable-speed or variable-capacity products that might be a good fit for your home, please reach out to our team at Save Home Heat Company today. Install quotes from our friendly estimators are always highly informative, low-pressure, and free!