Combustion and Ventilation Air, Indoor Units

Fig. 8: Minimum Clearances from Combustible

Surfaces – Outdoor Installations

Combustion and Ventilation Air

NOTE: Use of the heater in construction areas where fine particulate matter, such as concrete or dry-wall dust, is present may result in damage to the heater that is not covered by the warranty. If operated in a construction environment, a clean source of combustion air must be provided directly to the heater.

Indoor Units

The heater must be supplied with sufficient quantities of non-contaminated air to support proper combustion and equipment ventilation. Combustion air can be sup- plied via conventional means where combustion air is drawn from the area immediately surrounding the heater, or via direct vent, where combustion air is drawn directly from outside. All installations must com- ply with the requirements of the NFGC (U.S.) and B149 (Canada), and all local codes.

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

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

Reversing Air Filter

Follow these instructions to change the air duct con- nection from the left-hand side (standard) to the right-hand side:

1.Remove the four screws and the dust cover from the right-hand side of the heater.

2.Remove the four screws and the air filter bracket from the left-hand side of the heater.

3.Reverse the components and reattach in the new location, making sure that the air filter locking bracket is on the bottom. (The air filter locking bracket is reversible.)

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. 29 (horizontal) or Fig. 30 (vertical) of this manual (pages 31 and 32, respectively).

2.Provide adequate ventilation of the space occu- pied by the heater(s) by an opening(s) for ventilation air at the highest practical point com- municating 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 out- doors 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 the non-operating hours.

Direct-Ducted Combustion Air

In certain applications it may be desirable to duct the combustion air directly to the heater. This should be done with PVC, CPVC or single-wall galvanized duct- ing. The duct will attach directly to the collar on the air filter housing located on the side of the heater. The ducting is attached to the air filter housing collar using