Harman Stove Company PB 105 - Manual (Page 11)

11 3-90-07205R19_05/13
Venting
Fig. 3
Avoiding Smoke and Odors - Negative Pressure,
Shut-down and Electrical Power Failure.
To reduce the probability of back-drafting or burn
back in the pellet boiler during a power failure,
it must be able to draft naturally without exhaust
blower operation. Negative pressure in the house will
resist this natural draft if not accounted for during
installation. Heat rises in a house, and leaks out at
upper levels. This air must be replaced with air from
outside the dwelling, which normally flows into lower
levels. Vents and chimneys into basements and lower
levels can become the conduit for return air and reverse
under these conditions.
Hearth & Home Technologies strongly recommends
the use of outside air in all pellet boiler installations,
especially those on lower level and main floor
locations. Per national building codes, consideration
must be given to combustion air supply to all
combustion appliances. Failure to supply adequate
combustion air for all appliance demands may lead to
back-drafting of those and other appliances within the
home.
To reduce the probability of reverse drafting
during shut-down conditions, Hearth & Home
Technologies strongly recommends:
• Installing the pellet vent with a minimum vertical
run of 5 feet. Preferably terminating above the roof
line.
• Installing the outside air intake at least four feet
below the vent termination.
To prevent soot damage to exterior walls, and to
prevent re-entry of soot or ash into the house:
• Maintain specified clearances to windows, doors
and air inlets, including air conditioners.
• Vents should not be placed below ventilated soffits.
Run the vent above the roof.
• Avoid venting into alcove locations.
• Vents should not terminate under overhangs, decks
or onto covered porches.
• Maintain minimum clearance of 12” from the
vent termination to the exterior wall. Extending this
distance may be required if visual accumulation
occurs.