Lochinvar SNR150-100, SNA500-125 Minimum Recommended Combustion AIR Supply to Equipment Room

TM

Installation & Service Manual

1Determine water heater location (continued)

TABLE - 1B

MINIMUM RECOMMENDED COMBUSTION

AIR SUPPLY TO EQUIPMENT ROOM

	FIG. 1-3		FIG. 1-4		FIG. 1-5		FIG. 1-6
Model	*Outside Air from		*Outside Air from		**Inside Air from
	2 Openings Directly from		2 Ducts Delivered from		2 Ducts Delivered from Interior		*Outside Air from
Number
	Outdoors		Outdoors		Space		1 Opening Directly
	Top	Bottom	Top	Bottom	Top	Bottom	from Outdoors, in2
	Opening, in2	Opening, in2	Opening, in2	Opening, in2	Opening, in2	Opening, in2
SNR150-100	38	38	75	75	150	150	50
	(246 cm2)	(246 cm2)	(484 cm2)	(484 cm2)	(968 cm2)	(968 cm2)	(323 cm2)
SNR200-100	50	50	100	100	200	200	67
	(323 cm2)	(323 cm2)	(646 cm2)	(646 cm2)	(1,291 cm2)	(1,291 cm2)	(433 cm2)
SNA285-125	72	72	143	143	285	285	95
	(465 cm2)	(465 cm2)	(923 cm2)	(923 cm2)	(1,839 cm2)	(1,839 cm2)	(613 cm2)
SNA400-125	100	100	200	200	400	400	134
	(646 cm2)	(646 cm2)	(1,291 cm2)	(1,291 cm2)	(2,581 cm2)	(2,581 cm2)	(865 cm2)
SNA500-125	125	125	250	250	500	500	167
	(807 cm2)	(807 cm2)	(1,613 cm2)	(1,613 cm2)	(3,226 cm2)	(3,226 cm2)	(1,078 cm2)

*Outside air openings shall directly communicate with the outdoors. When combustion air is drawn from the outside through a duct, the net free area of each of the two openings must have twice (2 times) the free area required for Outside Air/2 Openings. The above requirements are for the water heater only; additional gas fired appliances in the equipment room will require an increase in the net free area to supply adequate combustion air for all appliances.

**Combined interior space must be 50 cubic feet per 1,000 Btu/hr input. Buildings MUST NOT be of *“Tight Construction”. For buildings of *“Tight Construction”, provide air openings into the building from outside.

*No combustion air openings are needed when the water heater is installed in a space with a volume NO LESS than 50 cubic feet per 1,000 Btu/hr of all installed gas fired appliances. Buildings MUST NOT be of *“Tight Construction”.

*”Tight Construction” is defined as a building with less than 0.40 ACH (air changes per hour).

Combustion air requirements are based on the latest edition of the National Fuel Gas Code, ANSI Z223.1; in Canada refer to the latest edition of CGA Standard CAN B149.1. Check all local code requirements for combustion air.

All dimensions based on net free area in square inches. Metal louvers or screens reduce the free area of a combustion air opening a minimum of approximately 25%. Check with louver manufacturers for exact net free area of louvers. Where two openings are provided, one must be within 12" (30cm) of the ceiling and one must be within 12" (30cm) of the floor of the equipment room. Each opening must have net free area as specified in the chart above (Table 1B). Single openings shall commence within 12" (30cm) of the ceiling.

￿Under no circumstances should the CAUTION equipment room ever be under negative pressure. Particular care should be taken where exhaust fans, attic fans, clothes dryers, compressors, air handling units, etc., may

take away air from the unit.

The combustion air supply must be completely free of any flammable vapors that may ignite or chemical fumes which may be corrosive to the appliance. Common corrosive chemical fumes which must be avoided are fluorocarbons and other halogenated compounds, most commonly present as refrigerants or solvents, such as Freon, trichlorethylene, perchlorethylene, chlorine, etc. These chemicals, when burned, form acids which quickly attack the stainless steel heat exchanger, headers, flue collectors, and the vent system.

The result is improper combustion and a non-warrantable, premature appliance failure.

EXHAUST FANS: Any fan or equipment which exhausts air from the equipment room may deplete the combustion air supply and/or cause a downdraft in the venting system. Spillage of flue products from the venting system into an occupied living space can cause a very hazardous condition that must be immediately corrected. If a fan is used to supply combustion air to the equipment room, the installer must make sure that it does not cause drafts which could lead to nuisance operational problems with the appliance.

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