RBI 8800 series Installation And Operation Instructions Manual page 5

SERIES 8800 & 8900 INSTALLATION AND OPERATING INSTRUCTIONS
Where communicating with the outdoors through
horizontal ducts, each opening shall have a minimum
/2000 Btu/hr, 1100 mm
free area of 1 in
2
input rating of all of the equipment in the enclosure.
When ducts are used, they must have the same cross-
sectional area as the free area of the opening to which
they connect.
Canadian installations must comply with CSA B149.1
when air supply is provided by natural air flow from the
outdoors for natural draft, partial fan-assisted, fan-
assisted, or power draft-assisted burners, there shall
be a permanent air supply opening(s) having a cross-
sectional area of not less than 1 in
(310 mm per kW) up to and including 1 million Btuh,
2
per 14,000 Btuh (155 mm
plus 1 in
2
of 1 million Btuh.
When calculating the free area necessary to meet
the make-up air requirements of the enclosure,
consideration must be given to the blockage effects
of louvers, grills and screens. Screens must have
a minimum mesh size of 1/4 in, 6.4 mm. If the free
area through a louver or grill is not known, ducts
should be sized per Table 2.
Figure 1 - Vertical Venting Using A Metal Chimney And Inside Air (8900/8800 Series)
2 FT .6 m
10 FT 3.4 m
/kW of the total
2
per 7,000 Btuh
2
per kW) in excess
2
3 FT 1 m
3 FT 1 m
5 FT 1.52 m
Table 2 - Make-up Air Louver Sizing
Required Cross Sectional Area
1/4 in 6.4 mm 75% Free Area
Input
(MBH) Wire Screen
cm
in 2
2
677
420 105
858
530 133
1019
630 158
1187
735 184
1355
210
840
1535
950 238
1697
1050 263
1871
1160 290
2032
1260 315
2213
1370 343
2374
368
1470
2548
1580 395
2716
1685 421
2890
1790 448
3065
1900 475
3226
2000 500
3871
600
2400
4516
2800 700
5161
3200 800
5806
3600 900
6452
4000 1000
25% Free Area
Metal Louvers Wooden Louvers
cm
in 2 in
2 2
903
140 420
1142
177 530
1355
210 630
1581
245 735
1806
280 840
2032
317 950
2258
350 1050
2497
387 1160
2710
420 1260
2948
457 1370
3161
490 1470
3400 1580 10,194
527
3626 1685 10,871
562
3852 1790 11,548
597
4084 1900 12,258
633
4303 2000 12,903
667
5161 2400 15,483
800
6019 2800 18,064
933
6884 3200 20,645
1067
7742 3600 23,226
1200
8600 4000 25,806
1333
RIOM-40
Page 5
cm
2
2710
3419
4064
4742
5419
6129
6774
7484
8129
8839
9484