Goodman *MVM96 Installation Instructions Manual page 11

9.3.1.4 Where used, a draft hood or a barometric draft regulator shall be
installed in the same room or enclosure as the appliance served so as to
prevent any difference in pressure between the hood or regulator and the
combustion air supply.
9.3.1.5 Makeup air requirements for the operation of exhaust fans, kitchen
ventilation systems, clothes dryers, and fireplaces shall be considered in
determining the adequacy of a space to provide combustion air require-
ments.
9.3.2 Indoor Combustion Air. The required volume of indoor air shall be
determined in accordance with the method in 9.3.2.1 or 9.3.2.2 except that
where the air infiltration rate is known to be less than 0.40 ACH, the
method in 9.3.2.2 shall be used. The total required volume shall be the sum
of the required volume calculated for all appliances located within the
space. Rooms communicating directly with the space in which the appli-
ances are installed through openings not furnished with doors, and through
combustion air openings sized and located in accordance with 9.3.2.3, are
considered a part of the required volume.
9.3.2.1* Standard Method. The minimum required volume shall be 50 ft
3 3
per 1,000/Btu/hour (4.8m /kW).
9.3.2.2* Known Air Infiltration Rate Method. Where the air infiltration
rate of a structure is known, the minimum required volume shall be deter-
mined as follows:
(1) For appliances other than fan-assisted, calculate using the following
equation:
Required Volume > ________ _________
other
(2) For fan-assisted appliances, calculate using the following equation:
Required Volume > ________ _________
fan
where:
I = all appliances other than fan-assisted input in Btu per hour
other
I = fan-assisted appliances input in Btu per hour
fan
ACH = air change per hour (percent of volume of space exchanged
per hour, expressed as a decimal)
(3) For purposes of this calculation, an infiltration rate greater than 0.60
ACH shall not be used in the equations in 9.3.2.2(1) and 9.3.2.2(2).
9.3.2.3 Indoor Opening Size and Location. Openings used to connect
indoor spaces shall be sized and located in accordance with the following:
(1)*Combining spaces on the same story. Each opening shall have a mini-
mum free area of 1 in. 2 /1000Btu/hr (2200 mm
rating of all appliances in the space but not less than 100 in.
One opening shall commence within 12 in. (300 mm) of the top, and
one opening shall commence within 12 in. (300 mm) of the bottom, of
the enclosure [see Figure A.9.3.2.3(1)]. The minimum dimension of
air openings shall be not less than 3 in. (80 mm).
21 ft 3 I
other
ACH 1000 Btu/hr
3
15 ft I
fan
ACH 1000 Btu/hr
2 /kW) of the total input
2
Figure A.9.2.3.3.(1) All Combustion Air from Adjacent
Indoor Spaces through Indoor Combustion Air Openings.
(2) Combining spaces in different stories. The volumes of spaces in dif-
ferent stories shall be considered as communicating spaces where such
spaces are connected by one or more openings in doors or floors
having a total minimum free area of 2 in.
of total input rating of all appliances.
9.3.3 Outdoor Combustion Air. Outdoor combustion air shall be pro-
vided through opening(s) to the outdoors in accordance with the methods
in 9.3.3.1 or 9.3.3.2. The minimum dimension of air openings shall not be
less than 3 in. (80 mm).
9.3.3.1 Two Permanent Openings Method. Two permanent openings,
one commencing within 12 in. (300 mm) of the top and one commencing
within 12 in. (300 mm) of the bottom, of the enclosure shall be provided.
The openings shall communicate directly, or by ducts, with the outdoors
or spaces that freely communicate with the outdoors, as follows:
(1)*Where directly communicating with the outdoors or where communi-
cating to the outdoors through vertical ducts, each opening shall have
a minimum free area of 1 in.
rating of all appliances in the enclosure. [See Figure A.9.3.3.1(1)(a)
and Figure A.9.3.3.1(1)(b).]
2
(0.60m ).
11
2
/1000 Btu/hr (4400 mm
2 2
/4000 Btu/hr (550 min /kW) of total input
2
/kW)