Heatmaster G100 Operation And Maintenance Manual page 12

G Series Outdoor Furnaces
COMBUSTION AIR
COMBUSTION AIR
Fireplaces, other furnaces, clothes dryers, exhaust fans, and other appliances all draw
air from the room in which they are located. Your G Series furnace adds to that draw,
making it important to ensure there is an adequate source of fresh air to offset these
demands. Otherwise, a negative pressure may be created in the room and starve com-
bustion in the furnace.
1. Determine the volume of space (cubic feet) in the room. Include in the calculation
adjacent rooms and areas not closed off by doors.
Volume (CF) = Length (ft) x Width (ft) x Height (ft)
2. Determine the air input requirements of all appliances in the space. Add the BTU
output of all appliances and round the total to the nearest 1000 BTU per hour. Your G
Series Furnace requires 85 CFM (cubic feet/minute).
3. Determine whether the space is 'confined' or 'unconfined' by dividing the total vol-
ume of the room by the total input requirements for all appliances in the room.
a. If the result is equal to or greater than 50 CF/1000 BTU per hour, then consider the
space 'unconfined.'
b. If the result is less than 50 CF/1000 BTU per hour, then consider the space
'confined.'
4. For an 'unconfined' space in a conventionally constructed building, the fresh air infil-
tration through cracks around windows and doors NORMALLY provides
adequate air for combustion and ventilation, and therefore no additional make up air is
required.
5. For a 'confined' space or an 'unconfined' space in a building with unusually tight con-
struction, an additional source of make up air is required. Please consult a HVAC pro-
fessional to determine the best way to supply make up air for this type of installation.
Important: The furnace room must never be in a negative pressure condition. Negative
pressure could result in smoke in the room.
www.heatmasterss.com
- 8 -