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Negative Pressure warning: When negative pressure is
present, an atmospherically vented fireplace (with a draft
hood) may not function properly and it may down draft. In
the case of a gas appliance, spillage of the combustion
gases may occur. This may create a dangerous carbon
monoxide situation in the house.
The causes of negative pressure to a house can include
the following:
Stack effect in the building.
Exhaust only appliances (mechanically and
atmospherically vented).
Inadequate make-up air (which is increasingly more
prevalent in new construction).
NOTE: This fireplace will operate correctly only if adequate
ventilation is provided to allow proper draft to the fireplace
system. Heat-N-Glo assumes no responsibility for the
improper performance of the fireplace system caused by
inadequate draft due to environmental conditions, down
drafts, tight sealing construction of the structure, or
mechanical exhausting devices which create a negative air
pressure within the structure where the fireplace is located.
It is recommended that all natural venting non-air tight gas
fireplaces have outside air connected to them. It is also
recommended that the building be mechanically or passively
balanced to allow atmospherically vented appliances, such
as top vented gas fireplaces with draft hoods, to draft
properly. If the home experiences negative pressure or is
likely to experience negative pressure, connection to an
outside air source is mandatory.
Installing Optional Outside Make-up Air: This unit is
equipped to accept outside air. By using outside make-up
air, the amount of room air used for combustion will be
reduced. It is recommended that an AK-225 air kit be used
with this appliance.
WARNING: IN A NEGATIVE PRESSURE CON-
DITION (LIKELY TO OCCUR IN NEW HOMES
THAT DO NOT HAVE ADEQUATE MAKE-UP AIR) THE
OUTSIDE AIR KIT MUST BE INSTALLED TO OB-
TAIN PROPER PERFORMANCE AND TO HELP PRE-
VENT SPILLAGE OF COMBUSTION GASES.
Step 3. Negative Pressure Make-up Air
Figure 4. Make-up Air
!
A 4-inch side collar and a 4-inch flexible air duct must be
installed to the outer wrap of the fireplace. See Figure 4.
After removing and discarding the outside air cover plate
attach the side collar to the outer wrap of the fireplace using
sheetmetal screws. Attach one end of the flex duct to the
side collar and the other end of the duct to the termination
cap. Use plastic tie straps to secure the ends of the flex
duct to the collar.
Detailed installation instructions for Model AK-225 Outside
Air kit are found in the kit. This kit cannot be used in Canada.
OUTSIDE AIR
COVER PLATE
OUTSIDE AIR
COLLAR
AIR DUCT