Goodman AMH8 Service Instructions Manual page 22

PRODUCT DESIGN
COMBUSTION AND VENTILATION AIR
REQUIREMENTS
P
OSSIBLE PROPERTY DAMAGE, PERSONAL INJURY OR DEATH MAY OCCUR
IF THE FURNACE IS NOT PROVIDED WITH ENOUGH FRESH AIR FOR PROPER
COMBUSTION AND VENTILATION OF FLUE GASES. MOST HOMES REQUIRE
OUTSIDE AIR BE SUPPLIED TO THE FURNACE AREA.
Improved construction and additional insulation in buildings
have reduced heat loss by reducing air infiltration and es-
cape around doors and windows. These changes have
helped in reducing heating/cooling costs but have created
a problem supplying combustion and ventilation air for gas
fired and other fuel burning appliances. Appliances that
pull air out of the house (clothes dryers, exhaust fans, fire-
places, etc.) increase the problem by starving appliances
for air.
If this furnace is to be installed in the same space with
other gas appliances, such as a water heater, ensure there
is an adequate supply of combustion and ventilation air for
the other appliances. Refer to the latest edition of the Na-
tional Fuel Gas Code NFPA 54/ANSI Z223.1 (Section 9.3),
or CAN/CGA B149 Installation Codes (Sections 7.2, 7.3,
or 7.4), or applicable provisions of the local building codes
for determining the combustion air requirements for the
appliances.
Most homes will require outside air be supplied to the fur-
nace area by means of ventilation grilles or ducts connect-
ing directly to the outdoors or spaces open to the outdoors
such as attics or crawl spaces.
The following information on air for combustion and ventila-
tion is reproduced from the National Fuel Gas Code NFPA
54/ANSI Z223.1 Section 9.3.
9.3* Air for Combustion and Ventilation.
9.3.1 General.
9.3.1.1 Air for combustion, ventilation, and dilution of flue gases for
appliances installed in buildings shall be obtained by application of one of
the methods covered in 9.3.2 through 9.3.6. Where the requirements of
9.3.2 are not met, outdoor air shall be introduced in accordance with methods
covered in 9.3.3 through 9.3.6.
Exception No. 1: This provision shall not apply to direct vent appli-
ances.
9.3.1.2 Appliances of other than natural draft design and other than Cat-
egory 1 vented appliances shall be provided with combustion, ventilation,
and dilution air in accordance with the appliance manufacturer's instruc-
tions.
9.3.1.3 Appliances shall be located so as not to interfere with proper
circulation of combustion, ventilation, and dilution air.
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.
22
WARNING
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
appliances 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
3 3
ft per 1,000/Btu/hour (4.8m /kW).
9.3.2.2* Known Air Infiltration Rate Method. Where the air infiltra-
tion rate of a structure is known, the minimum required volume shall be
determined 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
minimum free area of 1 in.
input rating of all appliances in the space but not less than 100 in.
2
(0.60m ). 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 2
/1000Btu/hr (2200 mm /kW) of the total
2