Raypak 503-2003 manual Optional Construction Air Filter, Direct Vent, TruSeal Combustion Air

SECTION C: Installation

CAUTION: Combustion air must not be contaminated by corrosive chemical fumes which can damage the heater and void the warranty. (See Section H.)

NOTICE: It is recommended that the intake vent be insulated to minimize sweating.

Optional Construction Air Filter

An optional construction air filter is available for use. The filter should be removed after construction is fin- ished to allow for unrestricted air flow to the heater.

Direct Vent

If outside air is drawn through the intake pipe directly to the unit for combustion:

1.Install combustion air direct vent in accordance with Fig. 24 (horizontal) or Fig. 25 (vertical) of this manual (pages 26 & 27 respectively).

2.Provide adequate ventilation of the space occupied by the heater(s) by an opening(s) for ventilation air at the highest practical point communicating with the outdoors. The total cross-sectional area shall be at least 1 in.2 of free area per 20,000 BTUH (111 mm2 per kW) of total input rating of all equipment in the room when the opening is communicating directly with the outdoors or through vertical duct(s). The total cross-sectional area shall be at least 1 in.2 of free area per 10,000 BTUH (222 mm2 per kW) of total input rating of all equipment in the room when the opening is communicating with the outdoors through horizontal duct(s).

3.In cold climates, and to mitigate potential freeze- up, Raypak highly recommends the installation of a motorized sealed damper to prevent the circula- tion of cold air through the heater during non- operating hours.

TruSeal™ Combustion Air

In addition to the 3 previous steps, combustion air may be ducted directly to the heater by using PVC, CPVC or sealed single-wall galvanized ducting. The duct will attach directly to the air collar located on the rear of the heater, using three or four sheet metal screws (not sup- plied) equally positioned around the circumference of the duct. The screen assembly should be removed be- fore attaching any air duct to the heater. The screws and duct connection point must be sealed with RTV (not supplied). TruSeal is generally used when damag- ing contaminants are present in the mechanical room.

All ducting should be self-supported.

CAUTION: Use TruSeal combustion air if damaging airborne contaminants are or may be present in the heater area. See Section H of this manual regarding air contamination.

Conventional Combustion Air Supply

U.S. Installations

All Air from Inside the Building

The confined space shall be provided with TWO per- manent openings communicating directly with an additional room(s) of sufficient volume so that the combined volume of all spaces meets the criteria for a room large in comparison (NFGC). The total input of all gas utilization equipment installed in the combined space shall be considered in making this determination. Each opening shall have a minimum free area of 1 in.2 per 1,000 BTUH (2,225 mm2 per kW) of the total input rating of all gas utilization equipment in the confined space, but not less than 100 in.2 (645 cm2). One open- ing shall commence within 12 in. (305 mm) of the top, and one opening shall commence within 12 in. (305

mm)of the bottom of the enclosure. The minimum dimension of air openings shall be not less than 3 in. (76 mm) in any direction.

All Air from Outdoors

The confined space shall communicate with the out- doors in accordance with one of the methods below. The minimum dimension of air openings shall not be less than 3 in. (76 mm) in any direction. Where ducts are used, they shall be at least of the same cross- sectional area as the net free area of the openings to which they connect.

1.Two permanent openings, one commencing within 12 in. (305 mm) of the top, and one com- mencing within 12 in. (305 mm) of the bottom of the enclosure, shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors.

a.Where directly communicating with the out- doors or where communicating to the outdoors through vertical ducts, each opening shall have a minimum free area of 1 in.2 per 4,000 BTUH (550 mm2 per kW) of total input rating of all equipment in the enclosure.

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