Bryant 120 instruction manual Installation, Volume, 21ft3, 1000 Btu/hr, 15ft3

Table 3 – Minimum Space Volumes for 100% Combustion, Ventilation, and Dilution from Indoors

	OTHER THAN FAN---ASSISTED TOTAL						FAN---ASSISTED TOTAL
ACH	(1,000s BTUH GAS INPUT RATE)					(1,000s BTUH GAS INPUT RATE)
	30	40	50		44	66	88	110	132	154
					Space Volume	(ft 3)
0.60	1,050	1,400	1,750	1,100		1,650	2,200	2,750	3,300	3,850
0.50	1,260	1,680	2,100	1,320		1,980	2,640	3,300	3,960	4,620
0.40	1,575	2,100	2,625	1,650		2,475	3,300	4,125	4,950	5,775
0.30	2,100	2,800	3,500	2,200		3,300	4,400	5,500	6,600	7,700
0.20	3,150	4,200	5,250	3,300		4,950	6,600	8,250	9,900	11,550
0.10	6,300	8,400	10,500	6,600		9,900	13,200	16,500	19,800	23,100
0.00	NP	NP	NP		NP	NP	NP	NP	NP	NP

NP = Not Permitted

312A

Table 3-Minimum Space Volumes were determined by using the following equations from the National Fuel Gas Code ANSI

Z223.1-2006/NFPA 54-2006, 9.3.2.2:

1.For other than fan-assisted appliances, such as a draft hood-equipped water heater:

Volume	=	21ft3	I other
		ACH	1000 Btu/hr
Other

A04002

2.For fan-assisted applicances such as this furnace:

Volume	=	15ft3	I fan
		ACH	1000 Btu/hr
Fan

	A04003
If:
Iother	= combined input of all other than fan-assisted
	appliances in Btuh/hr
Ifan	= combined input of all fan-assisted appliances in
	Btuh/hr
ACH	= air changes per hour (ACH shall not exceed 0.60.)

The following requirements apply to the Standard Method and to the Known Air Infiltration Rate Method.

1.Adjoining rooms can be considered part of a space if:

a.There are no closable doors between rooms.

b.Combining spaces on same floor level. Each opening shall have free area of at least 1 in.2/1,000 Btuh (2,000 mm2/kW) of the total input rating of all gas appliances in the space, but not less than 100 in.2 (0.06 m2). One opening shall commence within 12 in. (300 mm) of the ceiling and the second opening shall commence within 12 in. (300 mm) of the floor. The minimum dimension of air openings shall be at least 3 in. (80 mm). (See Fig. 8.)

c.Combining space on different floor levels. The volumes of spaces on different floor levels shall be considered as communicating spaces if connected by one or more permanent openings in doors or floors having free area of at least 2 in.2/1,000 Btuh (4,400 mm2/kW) of total input rating of all gas appliances.

2.An attic or crawlspace may be considered a space that freely communicates with the outdoors provided there are adequate permanent ventilation openings directly to outdoors having free area of at least 1-in.2/4,000 Btuh of total input rating for all gas appliances in the space.

3.In spaces that use the Indoor Combustion Air Method, infiltration should be adequate to provide air for combustion, permanent ventilation and dilution of flue gases. However, in buildings with unusually tight

construction, additional air MUST be provided using the methods described in the Outdoor Combustion Air Method section. Unusually tight construction is defined as Construction with:

a. Walls and ceilings exposed to the outdoors have a continuous, sealed vapor barrier. Openings are gasketed or sealed and

b.Doors and openable windows are weatherstripped and

c.Other openings are caulked or sealed. These include joints around window and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical and gas lines, etc.

Combination of Indoor and Outdoor Air

1.Indoor openings shall compy with the Indoor Combustion Air Method below and,

2.Outdoor openings shall be located as required in the Outdoor Combustion Air Method mentioned previously and,

3.Outdoor openings shall be sized as follows:

a.Calculate the Ratio of all Indoor Space volume divided by required volume for Indoor Combustion Air Method below.

b.Outdoor opening size reduction Factor is 1 minus the Ratio in a. above.

c.Minimum size of Outdoor openings shall be the size required in Outdoor Combustion Air Method above multiplied by reduction Factor in b. above. The minimum dimension of air openings shall be not less than 3 in. (80 mm).

INSTALLATION

UPFLOW INSTALLATION

Bottom Return Air Inlet

These furnaces are shipped with bottom closure panel installed in bottom return-air opening. Remove and discard this panel when bottom return air is used. To remove bottom closure panel, perform the following:

1.Tilt or raise furnace and remove 2 screws holding bottom filler panel. (See Fig. 9.)

2.Rotate bottom filler panel downward to release holding tabs.

3.Remove bottom closure panel.

4.Reinstall bottom filler panel and screws.

Side Return Air Inlet

These furnaces are shipped with bottom closure panel installed in bottom return-air opening. This panel MUST be in place when only side return air is used.

NOTE: Side return-air openings can be used in UPFLOW and most HORIZONTAL configurations. Do not use side return-air openings in DOWNFLOW configuration.

10