The Booster Fan: A Case Study in Home Comfort

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The Booster Fan: A Case Study in Home Comfort

Written by

  • Energy Efficiency
  • HVAC Experts
  • Real Life Case Study

    If you’ve been following our blog, you know that we pride ourselves on providing HVAC tips for the average homeowner while highlighting a variety of different products and services. But do you ever wonder how beneficial the products and services we recommend really are? In this real life case study,
    we’ll show you how a booster fan improved the life of one Siouxland family.

    The Family:

    Ryan and Samantha Gray live in Sioux City, Iowa. They both work in the computer science field, and share a home office: Ryan is a network engineer, and Samantha is a small-business owner. They have 4 children and are obsessed with living in the most earth-friendly manner possible. Efficiency is at the top of the priority list for these homeowners.

    The Problem:

    The Gray’s shared office is on the second floor of their nearly 100 year old home. During the non-winter months, the office becomes something of a sauna. While Samantha doesn’t mind the heat, Ryan was having trouble concentrating with temperatures around 85 degrees in the office. Worse, their computers had started to feel the burn, even shutting down at times. All the while, the main floor remains as cold as an icebox. Not exactly an ideal situation for people whose work depends on using their computers.

    The Gray’s house was built in 1919. At the time, the only sources of comfort in the home were a fireplace and coal furnace – no modern HVAC system to speak of. The house was built with high ceilings to optimized air flow and windows were strategically placed for a cross-breeze. Fast forward 100 years and the home has an awesome AC, but is severely limited by the house’s design. As is common with many older homes, the ducts in the Gray’s home weren’t designed to handle modern heating and cooling systems. The Gray’s (and their computers) are overheating and looking for answers.

    Possible Solutions:

    Home Zoning System

    With zoning, multiple thermostats operate dampers within the ductwork. Thermostats read the temperature of a certain zone, and then the dampers open or close based on the thermostat’s settings. You’re able to control the temperature in every room (or zone) of your home.

    Booster Fan

    A booster fan will help move air through the ducts. This add-on will not cure underlying defects, but it will “boost” air flow. A booster fan increases the amount of warm and cold air that makes it to a certain room. Before installing a booster fan, your home’s HVAC system will need to be inspected for problems that could be contributing to your air flow problems. Such problems include:

    • Clogged air filters
    • Leaks in windows and doors
    • Blocked return air registers
    • Dirty blower coil and/or wheel
    • Leaky ducts


    Ryan and Samantha discussed their cooling problem with one of our HVAC specialists. After careful thought and consideration, they chose to go with a booster fan. Why a booster fan and not a home zoning system? Well, let’s look at the facts:

    • The energy needed to increase air flow to their home office would be minimal.
    • They weren’t looking to keep the office at a chilly 65 degrees; they just want to be comfortable.
    • Though they are effective, unless the Gray’s were looking at making a major change like replacing ductwork or building on an addition to the home, installing the dampers and thermostats that go along with a home zoning system would be invasive.
    • The right booster fan can be economical, energy efficient and effective.

    Now, the Gray’s needed to choose which type of booster fan would be best for their home: register fan or inline duct fan.

    Register Fan

    Register fans or in-floor booster fans sit directly on the registers in the problem rooms. They are easy to install, inexpensive, and some come with their own thermostat. The biggest complaint of register fans is that they are noisy and prone to burnout/failures. They aren’t rated with a high enough airflow to make a huge difference – especially in our Sioux City climate, where temperature extremes fluctuate by more than 100 degrees over the course of a year. Some say this solution helps, and it’s inexpensive enough that it wouldn’t break the bank.

    Inline Duct Fan

    Mid-duct fans or inline duct fans will take up an entire width of ductwork or “replace” a section of ductwork. This inline duct fan would be placed on the run of ductwork that heads directly upstairs to the home office. Unlike the register fan, the inline booster fan would be able to pump the cold air from the lower floors up to the second floor office. (Bonus feature: it works on the inverse! Since the office is also difficult to keep warm during the winter, the booster fan can be used to pump warm air into the room, too.) An exposed section of ductwork is needed to install this kind of booster fan, and an HVAC professional would be needed for installation. They are quieter than register fans but a little more expensive (and many times more effective). With the help of an HVAC technician, you can choose the right sized unit, cfm rating, and features.

    It was quickly apparent that the inline duct fan would be the Gray’s booster fan of choice. They had an exposed section of ductwork, an experienced HVAC technician, and a list of reasons why the inline duct fan was the right fit for their home.


    After ensuring that there were no underlying issues with the ductwork, we installed an inline duct fan on the duct run that goes to the office. To allow them greater convenience and control over the temperature of the office, our technician also installed a remote control device: without leaving her keyboard, Samantha can simply press a button and cooler air is pushed from the downstairs up to the office. The AC does not run harder and the rest of the upstairs isn’t being unnecessarily cooled.

    Happy Customers?

    Now, we understand that all of the technical and/or mechanical detail in the world doesn’t matter if our customer isn’t happy with the solutions we provide. About 6 weeks after installing her booster fan, Samantha sent us a screenshot of her energy usage and this note about her HVAC specialist, Dave:

    Just wanted to let you know that Dave Wenzel has me seriously fangirling. His suggestion to install our booster fan allowed us to stop using the AC as much, without the office becoming a sauna. (Not that I wouldn’t love to sit in a sauna all day, but the computers get a little cranky when it’s too warm.) This means we save energy by A. Not running the AC, and B. Not forcing the computers to run their fans. Check out the graph! […] Seriously, that dude is really good at his job. So good, in fact, that I’d buy a tee shirt with his face on it. (Do you sell those?) Samantha Gray

    As the screenshot she sent illustrates, the Gray family’s energy use during the month of July was 1209 kWh and August was 724 kWh. Even though it was hotter during the month of August, they were able to use less energy to cool the home – in fact, they used less energy than the average customer used. (Something Samantha says has NEVER happened for her before!) Less energy used = less money spent. That’s a win-win for the environment and for the family’s budget. (Their computers are probably thanking them, too.)

    The Bottom Line

    A booster fan may not be the solution for everyone – that’s why we’ve always offered free estimates. We advise you to have an HVAC specialist take a thorough look at your ductwork to evaluate the problem. You can trust that our HVAC specialists will make the right recommendation, whether that is a simple filter replacement, booster fan, or home zoning system.

    Written by

  • Energy Efficiency
  • HVAC Experts