Combustion Air Control |

Combustion Air Control


Boilers require the proper amount of combustion air for efficient and safe combustion. Not enough air results in sooting, CO formation, back-fire, and damage to equipment – maybe even explosion. Too much air results in higher than necessary energy prices.

Louvers with motor controlled dampers linked to boiler burner controls is one way to reduce excess air during non-firing conditions. However, it is not as efficient as delivering the correct amount of air during the entire operating cycle. This is especially important when there is more than one piece of equipment that share the same space.

See  Oxygen Control for information on controlling O2 in the combustion process.


From the EXHAUSTO web site:

EXHAUSTO’s Modulating Combustion Air System, MCAS, is for installation and use in mechanical rooms containing heating appliances, like boilers and water heaters, or commercial laundry dryers.

The purpose of the system is to provide an exactly measured amount of combustion air for the appliances and eliminate the use of gravity air louvers.

It can be used in conjunction with any type of combustion system, whether a boiler, furnace, commercial dryer, etc. that is gas or oil-fired.

The MCAS System maintains a perfect, constant mechanical room pressure during the combustion process by modulating the fan capacity. The system creates and maintains a preset room pressure prior to or immediately after the appliances start. It can also be set to run continuously.

The system monitors the mechanical room pressure condition all of the time, and has an integrated safety function. Should the operating pressure fall more than 40% below the set point for more than 12 seconds, it deactivates the appliances to prevent a potentially hazardous situation.

More Information

Oxygen Control

Air Supply


1200 Northmeadow Parkway, STE 180
Roswell, Georgia, 30076
Telephone:  800-255-2923 FREE770-587-3238
Fax: 770-587-4731

Go to their web site at