Negative Air Pressure

  February 1, 2017      Bradford White

Negative air pressure is the flow or movement of air from the outside to the inside of a building.

Devices that pull air out of the building can create negative air pressure. This is especially true in dealing with kitchen or restaurant product applications. Cook top fans can move 200-400 cubic feet of air per minute, generating an enormous amount of negative air pressure. The use of exhaust fans, clothing dryers, furnaces, central vacuums or additional hood ranges may increase the presence of negative air pressure.

Possible Negative Air Pressure Issues:

• Slower recovery times
• Pilot flames will not stay lit
• Presence of Carbon monoxide
• Sooting around the burner assembly
• Flame rollout on heavy duty commercial models (Non FVIR models)
• Excessive condensation

Bradford White recommends installing power direct vent water heaters such as our ultra high efficiency eFSeries® in these applications, where negative air pressures are possible. Direct vent water heaters, both power and non, will reduce the potential of performance problems, nuisance outages, and premature failure of the water heater.

When too much negative air pressure is present, a building tries to replenish by engulfing positive air from the outside as much as possible.