What is Combustion Safety Testing?

When building performance professionals seal air leaks and improve insulation, they’re fundamentally changing how air moves through a building. This can have serious consequences for fuel-burning appliances like furnaces, water heaters, and gas stoves. That’s where combustion safety testing plays a critical role in weatherization work.

The challenge is that combustion appliances need adequate air supply to burn fuel safely and vent exhaust gases outside. Tightening a building’s envelope can create negative pressure conditions that interfere with proper venting, potentially causing backdrafting, spillage, or dangerous carbon monoxide buildup inside living spaces.

That’s why combustion safety testing before and after weatherization work protects both occupants and contractors. In this video, building science instructor Brynn Cooksey briefly explains the fundamentals of combustion appliance testing and why it belongs in your weatherization skill set.

Ready to learn more about combustion safety and other important building science testing? Enroll in Brynn’s BPI Building Analyst Technician (BA-T) Certification Training. 

Transcript below.

One of the things we talk about in the course is combustion safety. What combustion safety is…  when we go to weatherize a home or building, we have to determine if the home has combustion appliances. Are we going to make things worse by weatherizing that house?

So we have to check the combustion appliances before weatherization and after we do repairs, just to make sure that those exhaust appliances are exhausting the products of combustion outside properly.

It’s a very key mistake that some weatherization companies make by weatherizing a building shell and not accounting for the changes to the structure, which can affect combustion appliances.