Mt. Vernon Pellet Insert (AE)
R
C. Negative Pressure | D. Draft |
WARNING! Risk of Asphyxiation! Negative pressure can cause spillage of combustion fumes and soot.
Negative pressure results from the imbalance of air available for the appliance to operate properly. It can be strongest in lower levels of the house.
Causes include:
•Exhaust fans (kitchen, bath, etc.)
•Range hoods
•Combustion air requirements for furnaces, water heaters and other combustion appliances
•Clothes dryers
•Location of
•Imbalances of the HVAC air handling system
•Upper level air leaks such as:
-Recessed lighting
-Attic hatch
-Duct leaks
To minimize the effects of negative air pressure:
•Install the outside air kit with the intake facing prevailing winds during the heating season
•Ensure adequate outdoor air for all combustion appliances and exhaust equipment
•Ensure furnace and air conditioning return vents are not located in the immediate vicinity of the appliance
•Avoid installing the appliance near doors, walkways or small isolated spaces
•Recessed lighting should be a “sealed can” design
•Attic hatches weather stripped or sealed
•Attic mounted duct work and air handler joints and seams taped or sealed
Draft is the pressure difference needed to vent an ap- pliance successfully. When an appliance is drafting suc- cessfully, all combustion byproducts are exiting the home through the chimney.
Install through the warm airspace enclosed by the building envelope. This helps to produce more draft, especially dur- ing lighting and
Considerations for successful draft include:
•Preventing negative pressure
•Location of appliance and chimney
NOTICE: Hearth & Home Technologies assumes no responsibility for the improper performance of the chimney system caused by:
•Inadequate draft due to environmental conditions
•Downdrafts
•Tight sealing construction of the structure
•Mechanical exhausting devices
Page 14 | November 22, 2011 |
