Lochinvar RSB-i&s-05 A Conventional Negative Draft Venting System, Table - B Vent Pipe Sizes

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

VENTING

Vent installations for connection to gas vents or chimneys must be in accordance with Part 7, “Venting of Equipment,” of the latest edition of the National Fuel Gas Code, ANSI Z223.1, in Canada, the latest edition of CGA Standard B149 Installation Code for Gas Burning Appliances and Equipment or applicable provisions of the local building codes.

Adequate combustion and ventilation air must be supplied to the room where the appliance is installed in accordance with the latest edition of the National Fuel Gas Code, ANSI Z223.1, in Canada, the latest edition of CGA Standard B149 Installation Code for Gas Burning Appliances and Equipment, or applicable provisions of the local building codes.

The distance of the vent terminal from adjacent buildings, windows that open and building openings MUST comply with the latest edition of the National Fuel Gas Code, ANSI Z223.1, in Canada, the latest edition of CGA Standard B149 Installation Code for Gas Burning Appliances and Equipment.

Vent connection is made directly to the top of the appliance. This appliance is designed with a built-in draft diverter. No additional external draft hood is re- quired. The connection from the appliance vent to the common vent or chimney must be made as direct as possible.

FIG. 9 Conventional Negative Draft Vertical Venting

A CONVENTIONAL NEGATIVE DRAFT

VENTING SYSTEM

The negative draft in a conventional vent installation must be within the range of a negative 0.02 to 0.05 inches water column to ensure proper operation. All draft readings are made while the appliance is in stable operation (approximately 2 to 5 minutes).

Multiple appliance installations with combined venting or common venting with other negative draft applianc- es require that each appliance must have draft within the proper range. If the draft measured above the appliance’s built-in draft diverter exceeds the specified range in a dedicated chimney for a single appliance installation or in combined venting with other negative draft appliances, a barometric damper must be installed to control draft.

TABLE - B

VENT PIPE SIZES

Input Btu/hr	Flue Size
45,000	4"
75,000	5"
90,000	5"
135,000	6"
180,000	7"
199,999	7"
215,000	7"
260,000	8"
315,000	8"
360,000	9"
399,999	10"
500,000	10"

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