Verifying Sufficient Make Up Air

As our homes have become tighter to reduce the amount of infiltration losses through the building envelope, there are typically no sources for clothes dryers, kitchen/bathroom exhaust fans to pull make up air from.

Unfortunately, the chimney may become influenced by these exhaust systems and bring up concerns about safety (carbon monoxide), reliable operation and full service life of the heating system, hot water tank, chimney, etc.

A simple method to check for sufficient make up air is to put the home into winter heating or summer air conditioning operation (close all windows, doors, etc.) and fire up the various heating equipment.

While watching the O2/CO2 readings on the combustion analyzer, turn on the various exhaust systems (clothes dryer, kitchen/bathroom exhaust, etc.) one at a time and all simultaneously.

Changes in response to operating these systems suggests that there is not sufficient make up air to replace the air exhausted from the home.