Variable Speed Furnaces


animated variable speed furnace


As a homeowner, you know the value of having the right furnace for your house. Historically, you’ve installed a furnace that could handle the coldest day of the year, with a big enough blower to keep the air moving around. However, when that big blower kicked in, our family felt “The Blast”—they gave a shiver, and you heard complaints.

What if it was possible to even out the airflow—and the temperature—all while saving money on operating costs? Mechanical Air is here to serve you with improved technology.


How Do I Know If I Need To Replace My Old Furnace?


old furnace gas energy flames


Consider replacing your old furnace if:

  •       – Repair costs are more than half of the price of a new system.
  •       – The heating unit is over 15 years old.
  •       – Energy bills are steadily increasing.
  •       – Temperature is inconsistent, i.e., occupants can’t get comfortable.

Variable Speed Furnace Technology

Variable speed furnace technology gives you:

  •       – Gentle increase to airflow when the furnace kicks in, i.e., eliminates “The Blast”
  •       – Minimal noise when you want to hold temperature steady
  •       – Lower electricity consumption by the blower motor
  •       – High air quality – The amount of time that air is flowing through the furnace filters increases, catching harmful airborne particles



Contact us today!

One of our friendly technicians will arrange to review your current system and make recommendations.



Questions & Answers (Q&A)



Q: I thought that motors got less efficient when they operated below their optimal speed. How is it that this variable-speed furnace blower motor can use less energy at lower speeds?

A: The variable-speed system uses a particular VFD (Variable Frequency Drive) stepped motor system. The motor’s speed is modulated by changing the input signal’s frequency, thereby allowing this motor to be quite efficient throughout its operating range. That’s why according to the Office of Energy Efficiency & Renewable Energy, a variable-speed motor running continuously at half-speed may use up to 75% less power than a single-speed motor to move the same amount of air.



Q: If I got a Variable-Speed Furnace from Mechanical Air but later decided to add a high-efficiency filter, then would I have to change out the blower motor?

A: Furnace filters come with a reading called MERV (Minimum Efficiency Reporting Value). MERV ratings range from 1–16. Ordinary disposable-style filters have a MERV rating of 1–4. At Mechanical Air, we recommend a MERV rating of 5–8—a nice balance between filtration and airflow. But if you’re enthusiastic about air quality, then we recommend higher MERV ratings. MERV ratings of 9–12 are considered high-efficiency filters—capturing particulates in the range of 1 to 3 µm—but additional energy is required to push the air through these filters. MERV ratings of 13–16 are HEPA filters—stopping particles as small as 0.3 µm (a.k.a. hospital-grade super-high efficiency filters) but require even more energy to push the air through these filters. The variable-speed blower motor of the Mechanical Air Variable-Speed Furnace is perfect for these applications. The VFD Technology allows it to modulate the airflow through most filter densities to maintain proper air distribution throughout your building.



Q: I like the Mechanical Air Variable-Speed Furnace idea, but I’m not sure about the rest of my system. Can you help me?

A: Yes, the experts at Mechanical Air will work with you to review your whole system. Air leaks are common in older ductwork. We recommend products to seal ducts, including mastic, butyl tape, foil tape, or other heat-approved tapes. We’ll help you choose the best one for your system (and apply it for you, if you’d like). Another significant customer complaint is cold and hot spots in the building. Mechanical Air will evaluate and recommend appropriate changes to ducts and registers to even out airflow—for maximum comfort.



Q: How can I use a Mechanical Air Variable-Speed Furnace to improve my building’s indoor air quality?

A: Not only do the Mechanical Air Variable-Speed Furnaces cost significantly less to operate, but when used in the Constant Fan Mode, they maximize comfort and continuously vacuum the air to improve indoor air quality.

We're still open for business.

Your family's health is our highest priority. Mechanical Air is taking all precautions to protect you and your family against the spread of COVID-19. We understand that HVAC repairs can't always wait, and we're here to help. Call us at 801-679-4367 to address any questions and concerns and schedule an appointment with a free consultation.