J952V Installation Manual

ManualsBrandsOxbox ManualsFurnacesJ952V - 80k BTU - Two-Stage Gas Furnace - 95% AFUE

EXAMPLE

If the combined input rate of all appliances is less than or

equal to 100,000 Btuh, each opening must have a free

area of at least 100 in

. If the combined input rate of all

appliances is 120,000 Btuh, each opening must have a

free area of at least 120 in

CAUTION:

Exhaust fans, clothes dryers, ﬁreplaces and

other appliances that force air from the house

to the outdoors can create a negative pressure

inside the house, resulting in improper furnace

operation or unsafe conditions such as ﬂame roll

out. It is imperative that sufﬁcient air exchange

with the outdoors is provided to prevent

depressurization. Additional information about

testing negative pressure problems can be found

in the National Fuel Gas Code.

Air openings on top of the furnace and openings in closet

doors or walls must never be restricted. If the furnace is

operated without adequate air for combustion, the ﬂame roll-

out switch will open, turning off the gas supply to the burners.

IMPORTANT NOTE

This safety device is a manually reset switch. DO NOT

install jumper wires across these switches to defeat

their function or reset a switch without identifying

and correcting the fault condition. If a switch must be

replaced, use only the correct sized part speciﬁed in the

Replacement Parts List provided online.

Direct Vent Systems

Direct vent appliances draw combustion air from the outdoors

and vent combustion products back outside, isolating the

entire system from the indoor space. It is important to make

sure that the whole system is sealed and clearances to

combustibles are maintained regardless of the installation

being in a conﬁned or unconﬁned space.

Conventional Vent Systems - Conﬁned Spaces

A conﬁned space is an area with volume less than 50 cubic feet

per 1,000 Btuh of the combined input rates of all appliances

drawing combustion air from that space. Furnace closets,

small equipment rooms and garages are conﬁned spaces.

Furnaces installed in a conﬁned space which supply heated

air to areas outside the space must draw return air from

outside the space and must have the return air ducts tightly

sealed to the furnace. Ducts must have cross - sectional

area at least as large as the free area of their respective

openings to the furnace space. Attics or crawl spaces must

connect freely with the outdoors if they are the source of air

for combustion and ventilation.

The required sizing of these openings is determined by

whether inside or outside air is used to support combustion,

the method by which the air is brought to the space, and by

the total input rate of all appliances in the space. In all cases,

the minimum dimension of any combustion air opening is

3 inches.

Air From Inside

If combustion air is taken from the heated space, the two

openings must each have a free area of at least one square

inch per 1,000 Btuh of total input of all appliances in the

conﬁned space, but not less than 100 square inches of free

area. See

Example and Figure 2.

Figure 2. Combustion Air Drawn from Inside

TOTAL INPUT

RATING (BTUH)

MINIMUM FREE AREA

(EACH OPENING)

ROUND DUCT

DIAMETER

38,000 100 sq. In 12 inches

60,000 100 sq. In 12 inches

80,000 100 sq. In 12 inches

100,000 100 sq. In 12 inches

120,000 120 sq. In 13 inches

140,000 140 sq. In 14 inches

160,000 160 sq. In 15 inches

Vent or

Chimney

Furnace

Water

Heater

12” Max.

See

Notes

See

Notes

NOTES:

Each opening must be

at least 100 sq. in. or

1 sq. in. per 1,000 Btuh

of total input rating,

whichever is greater.

Openings must start at

no more than 12 inches

from the top and bottom

of the enclosure.

Outdoor Air from a Crawl Space or Vented Attic

When the openings can freely exchange air with the outdoors,

each opening shall have a minimum free area of 1 square

inch per 4,000 Btuh of total appliance input. The openings

shall exchange directly, or by ducts, with the outdoor spaces

(crawl or attic) that freely exchange with the outdoors. See

Figure 3.

Water

Heater

Vent or

Chimney

Furnace

Ventilation Louvers For

Unheated Crawl Space

Inlet Air

Ventilation Louvers

(each end of attic)

NOTE: Air openings shall

each have a free area of

not less than one square

inch per 4,000 Btuh of the

total input rating of all

equipment in the enclosure

Alter

nate

Air Inlet

Outlet

Air

Figure 3. Combustion Air Drawn from a Crawl

Space or Vented Attic