Teledyne EHE 2G-2. Combustion Air Requirements for One-Pipe Installation, 2G-3b. Piping Materials

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conversion can be done quite simply as follows (see Figures 2 and 3):

1.Remove the vent exhaust grille by removing the four screws which retain it. The grille, its gasket, and the screws may be discarded.

2.Place the vent collar gasket on the top of the heater aligning its center hole and screw holes with those in the top of the heater.

3.Place the vent collar over the gasket and fasten it in place with the screws and lockwashers provided. Be sure that all components are properly aligned. Screws must be tightened enough to assure a sealed joint without deforming the vent collar.

2G-2. Combustion Air Requirements for One-Pipe Installation

One-pipe indoor installations must have specific provisions for supply of combustion and ventilation air to the room in which the heater is located. Two air openings must be provided — one near the ceiling and one near the floor. When air is provided directly through an outside wall, each opening must have at least one square inch (6.5 square cm) of area per 4000 BTU/h of heater input. When air is provided indirectly through ducts from the outside, the openings and passages must have at least one square inch of area per 2000 Btu/h of heater input. These requirements are interpreted in Table 2.

	Required net free area in square inches (sq. cm)
	for each of 2 openings - one near ceiling and
Model	one near floor
	Directly Through an	Through
	Exterior Wall	Horizontal Ducts
220	55 (355)	110 (710)
350	88 (570)	175 (1130)

Table 2. Required Net Free Area of Openings for Combustion and Ventilation Air.

Note that the numbers indicate the net free area

—after allowing for the blockage of grille bars, etc. See applicable local codes and the previously-cited national codes for details. Even though codes may permit it, Teledyne Laars does not recommend installations with only “infiltration” as the means for provision of combustion air.

See Section 2G-3c for vent pipe sizing.

WARNING

Do not store any chemicals, cleaners, or other corrosive material near combustion air openings or in the room. Avoid location of dryer vents in the vicinity of combustion air openings. Failure to prevent corrosive materials from mixing with combustion air can result in reduced heater life and unsafe heater operation.

2G-3. Two-Pipe Installation (Direct Vent)

This section specifies installation requirements for combustion air and vent piping for “two pipe” installations. A two-pipe system provides isolation of the Hi-E2combustion system from the space in which the heater is installed. It has not only a vent pipe, but also a combustion air pipe to provide air directly from the outdoors. Research studies have shown that contaminants which may corrode internal heater parts are typically at much lower levels in outdoor air than in air from indoors.

Figure 4. Connection of combustion air pipe to heater.

2G-3a. Connection of Combustion Air Pipe

A collar for combustion air pipe connection is provided in the heater at the inlet of the filter box. As shown in Figure 4, the combustion air pipe is routed through the side of the heater to the filter box connection. Remove the cover plate from the left side panel to provide access for the air pipe.

2G-3b. Piping Materials

Vent piping must be corrosion resistant because combustion condensate is usually present on its internal surfaces. Only the following materials are acceptable for vent piping:

PVC	Class 100, Class 125 or Schedule 40
CPVC	Schedule 40
29-4C®	Stainless steel venting materials listed for
	venting of condensing gas-fired appliances.

29-4C®is a trademark of Allegheny Teledyne.