Air for combustion and ventilation, Continued, Ventilation air – Desa VYM27NRPR User Manual

Page 6

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6

AIR FOR COMBUSTION
AND VENTILATION

Continued

A.

Rework worksheet, adding the space of an adjoining room. If the
extra space provides an unconfined space, remove door to adjoining
room or add ventilation grills between rooms. See Ventilation Air From
Inside Building
below.

B.

Vent room directly to the outdoors. See Ventilation Air From Out-
doors
.

C.

Install a lower Btu/Hr heater, if lower Btu/Hr size makes room unconfined.

If the actual Btu/Hr used is less than the maximum Btu/Hr the space can
support, the space is an unconfined space. You will need no additional fresh
air ventilation.

WARNING: If the area in which the heater may be

operated is smaller than that defined as an uncon-
fined space or if the building is of unusually tight
construction, provide adequate combustion and ven-
tilation air by one of the methods described in the
National Fuel Gas Code, ANSI Z223.1/NFPA 54, Sec-
tion 5.3 or applicable local codes.

VENTILATION AIR

Ventilation Air From Inside Building

This fresh air would come from an adjoining unconfined space.
When ventilating to an adjoining unconfined space, you must
provide two permanent openings: one within 12" of the ceiling and
one within 12" of the floor on the wall connecting the two spaces
(see options 1 and 2, Figure 2). You can also remove door into
adjoining room (see option 3, Figure 2). Follow the National Fuel
Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion
and Ventilation
for required size of ventilation grills or ducts.

Ventilation Air From Outdoors

Provide extra fresh air by using ventilation grills or ducts. You must
provide two permanent openings: one within 12" of the ceiling and
one within 12" of the floor. Connect these items directly to the
outdoors or spaces open to the outdoors. These spaces include attics
and crawl spaces. Follow the National Fuel Gas Code, ANSI Z223.1/
NFPA 54, Section 5.3, Air for Combustion and Ventilation
for
required size of ventilation grills or ducts.

IMPORTANT:

Do not provide openings for inlet or outlet air into

attic if attic has a thermostat-controlled power vent. Heated air
entering the attic will activate the power vent.

Figure 3 - Ventilation Air from Outdoors

Figure 2 - Ventilation Air from Inside Building

Outlet
Air

Ventilated
Attic

Outlet
Air

Inlet
Air

Inlet Air

Ventilated

Crawl Space

To

Crawl

Space

To Attic

Or

Remove

Door into
Adjoining

Room,
Option

3

Ventilation Grills

Into Adjoining Room,

Option 2

Ventilation

Grills

Into Adjoining

Room,

Option 1

12"

12"

AIR FOR COMBUSTION AND VENTILATION

Determining Fresh-Air Flow For Heater Location (Cont.)
Ventilation

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