Venting General Guidelines, Venting Categories

VENTING - GENERAL GUIDELINES

The following guidelines apply to all categories to follow.

Table 4

Vent Systems

Termination Clearance Requirements

Structure	Minimum Clearances for
	Termination Locations

	4 feet below
Door, window or any gravity vent inlet
Door, window or any gravity vent inlet	4 feet horizontally

	1 foot above

Forced air inlet within 10 ft.	3 feet above

Adjoining building or parapet	6 feet

Adjacent public walkways	7 feet above grade

Electric, gas meters & regulators	4 feet horizontal

Do not damper or add heat recovery devices to the ﬂue piping. Failure to open such a damper prior to operating the gas unit heater will result in the spillage of ﬂ ue gas into the occupied space.

Avoid installing units in areas under negative pressure. When required, a flue vent fan should be installed in accordance with the instructions included with the fan.

Vent connectors serving Category I and Category

IIheaters shall not be connected into any portion of mechanical draft systems operating under positive vent pressure.

Maintain 1-inch (25.4mm) clearance between the vent pipe and combustible materials.

ADDITIONAL REQUIREMENT

FOR CANADIAN INSTALLATIONS

REFER TO SPECIFICATION TABLE AND INSTALLA- TION MANUAL FOR PROPER USAGE.

*The following instructions apply to Canadian installations in addition to installation and operating instructions.

1.Installation must conform with local building codes, or in the absence of local codes, with current CGA B149.1, Installation Codes for Natural Gas Burning Appliances and Equipment, or CGA B149.2, Installation Codes for Propane Gas Burning Appliances and Equipment.

2.Any reference to U. S. standards or codes in these instructions are to be ignored, and the applicable Canadian standards or codes applied

ANSI now organizes vented appliances into four categories.

Venting Categories

	Non
	Condensing	Condensing
Negative
Vent	I	II
Pressure
Positive
Vent	III	IV
Pressure

Category I

Includes non-condensing appliances with negative vent pressure, like the traditional atmospheric unit heater.

Category II

Groups condensing appliances with negative vent pressure.

Category III

Appliances are non-condensing and operate with a positive vent pressure.

Category IV

Covers condensing appliances with positive vent pressure.

NOTICE: Category II and IV do not apply to equip- ment speciﬁed within this manual.