Combustion and ventilation air – Raypak 302B-902B User Manual

Page 12

Fig. 8: Minimum Clearances from Combustible

Surfaces – Outdoor Installations

Combustion and Ventilation Air

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.

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. 26 (horizontal) or Fig. 27 (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.

of free

area per 20,000 BTUH (111 mm

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.

of free

area per 10,000 BTUH (222 mm

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

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.

NOTE: Use of the heater in construction areas

where fine particulate matter, such as concrete or

drywall 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.