15
openings must be installed to provide fresh air for combustion,
ventilation and dilution in conned spaces. The required size for
the openings is dependent on the method used to provide fresh
air to the conned space AND the total Btu/hr input rating of all
appliances installed in the space.
exhaust fans
Where exhaust fans are installed, additional air shall be provided
to replace the exhausted air. When an exhaust fan is installed
in the same space with a water heater, sufcient openings to
provide fresh air must be provided that accommodate the
requirements for all appliances in the room and the exhaust fan.
undersized openings will cause air to be drawn into the room
through the water heater’s vent system causing poor combustion.
Sooting, serious damage to the water heater and the risk of re
or explosion may result. it can also create a risk of asphyxiation.
louVers and grilles
The free areas of the fresh air openings in the instructions that
follow do not take in to account the presence of louvers, grilles or
screens in the openings.
The required size of openings for combustion, ventilation and
dilution air shall be based on the “net free area” of each opening.
Where the free area through a design of louver or grille or screen
is known, it shall be used in calculating the size of opening
required to provide the free area specied. Where the louver and
grille design and free area are not known, it shall be assumed
that wood louvers will have 25% free area and metal louvers and
grilles will have 75% free area. Non motorized louvers and grilles
shall be xed in the open position.
Never obstruct the ow of ventilation air. if you have any doubts
or questions at all, call your gas supplier. failure to provide the
proper amount of combustion air can result in a re or explosion
and cause property damage, serious bodily injury or death.
unconfined space
An unconned Space is one whose volume iS NoT LeSS THAN
50 cubic feet per 1,000 Btu/hr (4.8 cubic meters per kW) of the
total input rating of all appliances installed in the space. Rooms
communicating directly with the space, in which the appliances
are installed, through openings not furnished with doors, are
considered a part of the unconned space.
Makeup air requirements for the operation of exhaust fans,
kitchen ventilation systems, clothes dryers and replaces shall
also be considered in determining the adequacy of a space to
provide combustion, ventilation and dilution air.
unusually tight construction
in unconned spaces in buildings, inltration may be adequate to
provide air for combustion, ventilation and dilution of ue gases.
However, in buildings of unusually tight construction (for example,
weather stripping, heavily insulated, caulked, vapor barrier, etc.)
additional air must be provided using the methods described in
the Conned Space section that follows.
confined space
A Conned Space is one whose volume iS LeSS THAN 50 cubic
feet per 1,000 Btu/hr (4.8 cubic meters per kW) of the total input
rating of all appliances installed in the space.
Venting installation
Venting
THe iNSTRuCTioNS iN THiS SeCTioN oN VeNTiNG muST
Be foLLoWeD To AVoiD CHoKeD ComBuSTioN oR
ReCiRCuLATioN of fLue GASeS. SuCH CoNDiTioNS
CAuSe SooTiNG oR RiSKS of fiRe AND ASPHYXiATioN.
Heater must be protected from freezing downdrafts.
Remove all soot or other obstructions from the chimney that will
retard a free draft.
Type B venting is recommended with these heaters. for typical
venting application see TeCHNiCAL DATA VeNTiNG on pages
17 and 18.
This water heater must be vented in compliance with all local
codes, the current revision of the National fuel Gas Code (ANSi-
Z223.1) and with the Category i Venting Tables.
if any part of the vent system are exposed to ambient temperatures
below 40°f it must be insulated to prevent condensation.
• Do not connect the heater to a common vent or chimney with
solid fuel burning equipment. This practice is prohibited by
many local building codes as is the practice of venting gas
red equipment to the duct work of ventilation systems.
figure 11. figure 12.
• Where a separate vent connection is not available and the vent
pipe from the heater must be connected to a common vent with
an oil burning furnace, the vent pipe should enter the smaller
common vent or chimney at a point above the large vent pipe.