Oxbox J951X D Series, Installation Instructions Manual

7

IMPORTANT INFORMATION:

• This furnace must be vented in compliance with 

the current revision of the National Fuel Gas Code  

(ANSI-Z223.1/NFPA54). Instructions for determining the 

adequacy of an installation can be found in the current 

revision of the NFGC (ANSI Z223.1 / NFPA54). Refer 

to the NFGC for approved vent tables. Consult local 

codes for special requirements. These requirements 

are for US installations as found in the NFGC.

•  Furnace installation using methods other than those 

described in the following sections must comply with 

the National Fuel Gas Code (NFGC) and all applicable 

local codes.

• Requirements in Canada (B149.1) are structured 

differently. In Canada, venting shall conform to 

the requirements of the current (CAN/CSA B149.1) 

installation codes. Consult local codes for special 

requirements.

•  Provisions must be made during the installation of 

this furnace that provide an adequate supply of air 

for combustion. The combustion air from the outside 

needs to be clear of chemicals that can cause corrosion. 

The inlet pipe should not be placed near corrosive 

chemicals such as those listed on 

page 5

.

 WARNING:

Upon completion of the furnace installation, 

carefully inspect the entire flue system both 

inside and outside the furnace to assure it is 

properly sealed. Leaks in the flue system can 

result in serious personal injury or death due 

to exposure of flue products, including carbon 

monoxide.

 WARNING:

This furnace must not be vented with other 

appliances, even if that appliance is of the 

condensing type. Common venting can result 

in severe corrosion of other appliances or their 

venting and can allow combustion gases to 

escape through such appliances or vents. Do 

not vent the furnace to a fireplace chimney or 

building chase.

This condensing furnace is certified for installation either as 

a Direct Vent (2-pipe) or Conventional (1-pipe) appliance. 

Direct Vent appliances draw combustion air from the outdoors 

and vent combustion products back outside. Installation 

with air taken from around the furnace is often referred to 

as Conventional installation - i.e. only the vent (exhaust) 

pipe is provided.
Another important consideration when selecting one or 

two pipe installation is the quality of the Indoor air which 

can sometimes be contaminated with various household 

chemicals . These chemicals can cause severe corrosion 

in the furnace combustion system. A 2-pipe installation has 

the additional advantage that it isolates the system from the 

effects of negative pressure in the house.

 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 

how to test for negative pressure problems can 

be found in the NFGC.

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 Furnaces

Direct Vent (2-pipe) furnaces draw combustion air directly from 

the outdoors and then vent the 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

.