Service Clinic: The Bathroom Exhaust Fan

The time to discuss this with customers is during an HVAC service call or at the time of equipment replacement and system upgrades. Have you been overlooking your customer's ventilation systems or the 'V' in HVAC?

What's Your Budget?
The budget to swap out an existing small bath fan may not be a worthwhile standalone project because it sells for less than $200. However, adding exhaust fan upgrades to an equipment replacement job adds real value and benefits to the project. On the other hand, replacing the exhaust fan in a large master bath where a new water-jet tub was just installed may exceed $1000 or more and can be a valuable and profitable job. 

When discussing bath fan options with customers, it's important to assess their wants and needs accurately and consider airflow to each bathroom before making your recommendations.   

Variables to consider when discussing bath fan upgrades and budgets with your customers should include:

Exhaust fan airflow capacity – Size the fan to handle the ventilation needs of the room. You determine fan airflow by the room size number of fixtures and the fan's controls. 

Ducting – Exhaust air must be ducted outdoors. Existing exhaust ducts may only be three-inch aluminum flex. Its size may be the reason airflow is so restricted. Usually, when you replace a new fan, you also replace the duct. Should it be flex, hard pipe, or rectangular duct?

Timers and speed controls – Some fan replacements will reuse the existing light switch. Some customers may want a multi-position speed control. The Cadillac version may be an automatic multi-speed control with a shut-off timer with a continuous low-flow ventilation setting to ventilate the home.

Your customers will look to you for guidance with each decision about these options above. So, it's your job to know and provide the answers they'll need to make the right decisions. 

Consider several pre-packaged bath fan options with flat-rate pricing. This tool will make it easy for your team to size and price replacement bath fans and simple for your customers to buy. 

This really happened…
Most important is what your customer wants and how valuable the desired outcome is to them.

When completing a system upgrade by balancing a home with a customer named Janet, I routinely measured the master bath fan airflow. The hood revealed its airflow was near 40 cfm. She was a beautiful woman who always looked perfect. When she heard 40 "buckets of air per minute," her immediate response was to ask if I could increase airflow to 500. I wasn't sure why, but she was very motivated to increase airflow.

Back at the shop, I priced the new fan system. I stopped by the house fairly early the next morning, and a woman came to the door. I asked to speak to Janet. She exclaimed, "Oh Rob, it's me without makeup!" I immediately understood why removing humidity and having a clear mirror in the bathroom was important. The next day we installed a powerful bath exhaust fan with a four-speed controller. From that day to now, she looks marvelous. And I know why. 

How much airflow?
Most ventilation codes, standards, and manufacturer recommendations are pretty vague or overly generalized when recommending bath fan airflow requirements. Many quote a default of 50 cfm for a bathroom and call it good. Of course, you should check with local code officials for a barometer reading of what their current requirements may be.

When discussing bath fan options with customers, it's important to assess their wants and needs accurately and consider airflow to each bathroom before making your recommendations.   

An inquiry during a training class by Mike Meredith of Munn's Sales & Service in Florida gave birth to a residential bath fan sizing table for field use. Mike needed a quick reference table to size fans for replacement opportunities he finds in the field. It has been a worthwhile project, and we decided to share it with you.

Of course, there are assumptions made. Some bathroom airflow conditions may fall outside of assumed parameters and perhaps local code requirements, so please check first. We assumed a ceiling height of eight feet, a single-speed fan, and an on-off switch. Another assumption is that the bigger the room (square feet), the more fixtures the bath may contain.

The table includes the typical number of fixtures and provides added exhaust airflow values at the bottom. It also contains other selection suggestions. We looked at various codes, standards, and manufacturer recommendations in the creation of this table. Hopefully, it will serve as a quick reference to help you choose the right fan size to recommend in the field.