RBI SERIES 8800 - Page 5

SERIES 8800 & 8900 INSTALLATION AND OPERATING INSTRUCTIONS Page 5
Figure 1 - Vertical Venting Using A Metal Chimney And Inside Air (8900/8800 Series)
10 FT 3.4 m
2 FT .6 m
3 FT 1 m
3 FT 1 m
5 FT 1.52 m
RIOM-40
Where communicating with the outdoors through
horizontal ducts, each opening shall have a minimum
free area of 1 in
2
/2000 Btu/hr, 1100 mm
2
/kW of the total
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
2
per 7,000 Btuh
(310 mm
2
per kW) up to and including 1 million Btuh,
plus 1 in
2
per 14,000 Btuh (155 mm
2
per kW) in excess
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.
Table 2 - Make-up Air Louver Sizing
Required Cross Sectional Area
Input 1/4 in 6.4 mm 75% Free Area 25% Free Area
(MBH) Wire Screen Metal Louvers Wooden Louvers
in
2
cm
2
in
2
cm
2
in
2
cm
2
420 105 677 140 903 420 2710
530 133 858 177 1142 530 3419
630 158 1019 210 1355 630 4064
735 184 1187 245 1581 735 4742
840 210 1355 280 1806 840 5419
950 238 1535 317 2032 950 6129
1050 263 1697 350 2258 1050 6774
1160 290 1871 387 2497 1160 7484
1260 315 2032 420 2710 1260 8129
1370 343 2213 457 2948 1370 8839
1470 368 2374 490 3161 1470 9484
1580 395 2548 527 3400 1580 10,194
1685 421 2716 562 3626 1685 10,871
1790 448 2890 597 3852 1790 11,548
1900 475 3065 633 4084 1900 12,258
2000 500 3226 667 4303 2000 12,903
2400 600 3871 800 5161 2400 15,483
2800 700 4516 933 6019 2800 18,064
3200 800 5161 1067 6884 3200 20,645
3600 900 5806 1200 7742 3600 23,226
4000 1000 6452 1333 8600 4000 25,806