www.desatech.com
119169-01E 5
AIR FOR COMBUSTION
AND VENTILATION
WARNING: This heater shall
not be installed in a confined
space or unusually tight con-
struction unless provisions are
provided for adequate combus-
tionandventilationair.Readthe
following instructions to insure
proper fresh air for this and
other fuel-burning appliances
in your home.
Today’shomes are builtmore energy efficient
thanever. New materials, increasedinsulation
and new construction methods help reduce
heat loss in homes. Home owners weather
strip and caulk around windows and doors
to keep the cold air out and the warm air in.
During heating months, home owners want
their homes as airtight as possible.
While it is good to make your home energy
efficient, your home needs to breathe. Fresh
air must enter your home.All fuel-burning ap-
pliancesneed fresh air for proper combustion
and ventilation.
Exhaust fans, fireplaces, clothes dryers and
fuelburningappliancesdrawairfromthehouse
to operate. You must provide adequate fresh
airforthese appliances.Thiswillinsureproper
venting of vented fuel-burning appliances.
PROVIDING ADEQUATE
VENTILATION
The following are excerptsfrom National Fuel
Gas Code, ANSI Z223.1/NFPA 54, Section
5.3, Air for Combustion and Ventilation.
All spaces in homes fall into one of the three
following ventilation classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
Theinformationonpages5through7will help
youclassifyyourspaceandprovideadequate
ventilation.
Unusually Tight Construction
The air that leaks around doors and windows
may provide enough fresh air for combustion
and ventilation. However, in buildings of un-
usually tight construction, you must provide
additional fresh air.
Unusually tight construction is defined as
construction where:
a. walls and ceilings exposed to the outside
atmosphere have a continuous water
vapor retarder with a rating of one perm
(6 x 10-11 kg per pa-sec-m2) or less with
openings gasketed or sealed and
b. weather stripping has been added on
openable windows and doors and
c. caulking or sealants are applied to areas
such as joints around window and door
frames, between sole plates and floors,
between wall-ceiling joints, between wall
panels,atpenetrationsforplumbing,electri-
cal and gas lines and at other openings.
If your home meets all of these three criteria,
you must provide additional fresh air. See
Ventilation Air From Outdoors, page 7.
If your home does not meet all of the three
criteriaabove,proceedto Determining Fresh-
Air Flow For Heater Location, page 6.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1/
NFPA54definesaconfinedspaceasaspace
whose volume is less than 50 cubic feet per
1,000 Btu per hour (4.8 m3per kw) of the ag-
gregateinput rating of all appliancesinstalled
in that space and an unconfined space as a
spacewhosevolume is not less than 50 cubic
feet per 1,000 Btu per hour (4.8 m3per kw)
of the aggregate input rating of all appliances
installedinthatspace. Rooms communicating
directlywiththespaceinwhichtheappliances
areinstalled*,throughopenings not furnished
with doors, are considered a part of the un-
confined space.
* Adjoining rooms are communicating only if
therearedoorlesspassagewaysor ventilation
grills between them.
