Slant/Fin CHS-399 - Manual (Page 12)

Slant Fin Corp. │ Installation and Operation Instructions CHS Series
12
and 6 in. from the front of the appliance. The opening shall directly communicate with the outdoors or shall
communicate through a vertical or horizontal duct to the outdoors or spaces that freely communicate with the
outdoors (see Figure 4-1e) and shall have a minimum free area of the following:
a. 1 in.
2 /3000 Btu/hr of the total input rating of all appliances located in the enclosure, and
b. Not less than the sum of the areas of all appliance vent connectors in the space.
3. Combination Indoor and Outdoor Combustion Air – The use of a combination of indoor and outdoor
combustion air shall be in accordance with the following:
a. Indoor Openings – where used, openings connecting the interior spaces shall comply with “Indoor
Combustion Air – Opening and Size and Location” described above.
b. Outdoor Openings – Outdoor opening(s) shall be located in accordance with “Outdoor Combustion Air
– Opening Size and Location” described above.
c. Outdoor Opening(s) Size – The outdoor opening(s) size shall be calculated in accordance with the
following:
i. The ratio of interior spaces shall be the available volume of all communicating spaces divided by the
required volume (i.e. 50 cubic ft per 1000 Btu/hr if 0.4 ACH or greater).
ii. The outdoor size reduction factor shall be 1 minus the ratio of interior spaces.
iii. The minimum size of outdoor opening(s) shall be the full size of outdoor opening(s) calculated in
accordance with “Outdoor Combustion Air – Opening Size and Location” described above, multiplied
by the reduction factor. The minimum dimension of air openings shall not be less than 3 in.
Figure 4-1(a) Indoor Air Figure 4-1(b) Two Vertical Ducts Figure 4-1(c) Two Vertical Duct
Figure 4-1(d) Two Horizontal Ducts Figure 4-1(e) One Duct Options
Opening (within
1ft of ceiling)
Opening (within
1ft of floor)
Exhaust Vent
Opening
Opening
Exhaust Vent
Ventilation Louvers
(each end of attic)
Ventilated & unheated
crawl space
Exhaust Vent
Ventilation Louvers
(each end of attic)
Opening
Opening (duct
extended to within
1ft of floor)
Exhaust Vent
Opening (within
1ft of ceiling)
Opening (within
1ft of floor)
Exhaust Vent
Ventilation Louvers
(each end of attic)
Opening Option B
(within 1ft of ceiling)
Opening Option A