Design Guidelines For Outside Combustion Air Connection - Magnum 6500 Owner's Manual

DESIGN GUIDELINES FOR OUTSIDE COMBUSTION AIR CONNECTION

OUTSIDE MAKE-UP AIR FOR COMBUSTION IS REQUIRED ON ALL INSTALLATIONS
1) For all Furnace installations, it is REQUIRED that the furnace combustion air intake be connected to
a fresh air intake outside. If the home is newer or has been tightly insulated it is imperative to the
operation of the unit to install outside combustion air and also have makeup air provided for the home.
It is the responsibility of the installer and homeowner to determine and achieve proper balancing of
fresh air for the home and for the appliance. If proper balancing of the fresh air is not achieved the
furnace will not be able to operate correctly and serious damage to the heat exchangers will happen.
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2) Connection to outside the house is REQUIRED for mobile home installations.
3) Fresh-Air pipe 4 inches in diameter is approved to use for outside air connections (straight or
flexible). PVC pipe is allowed. You might need to use 6" diameter fresh air piper if the run is over
10 feet long.
4) When air inlet is connected to the outside, it MUST be terminated with a vertical 90-degree bend
(down) or with a wind hood. Failure to do so could result in a burn back during high winds blowing
directly up the air inlet during a simultaneous power failure (see diagram above).
5) It is important not to terminate the inlet of the fresh air intake too close to the venting outlet for the
smoke. It is recommended that the inlet for the fresh air is a minimum of 3 feet away from the venting
outlet and at least 1-2 feet below.
6) Blockage, excessive length, or bends in the air intake pipe will starve the furnace of combustion air.
A 90-degree bend is equivalent in restriction to approximately 30 inches of straight inlet pipe. Use 4"
diameter fresh air intake to alleviate these issues.
7) Furnace must have fresh air (oxygen) to perform properly. Incomplete combustion is caused by
negative pressure in the home when the furnace is starved for fresh air. This causes carbon monoxide
(CO) and can be dangerous. Provisions for outside air must be made and kept clean and free from
blockage outside the home.
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