HomeMy WebLinkAboutImage (10) Directions-In order to determine the makeup air, Table 501.4.1 must be filled out(see below). For most new installations,column
A will be appropriate,however,if atmospherically vented appliances or solid fuel appliances are installed, use the appropriate
column.For existing dwellings,see IMC 501.4.3. Please note,if the makeup air quantity is negative,no additional makeup air will
be required for ventilation,if the value is positive refer to Table 501.3.2 and size the opening. Transfer the cfm,size of opening and
type(round,rectangular,flex or rigid)to the last line of section D. The make-up air supply must be installed per IMC 501.4.2.3.
Table 501.4.1
PROCEDURE TO DETERMINE MAKEUP AIR QUANITY FOR EXHAUST EQUIPMENT IN DWELLINGS
(Additional combustion air will be required for combustion appliances,see KAIR method for calculations)
One or multiple power One or multiple fan- One atmospherically vent Multiple atmospherically
vent or direct vent assisted appliances and gas or oil appliance or vented gas or oil
appliances or no power vent or direct vent one solid fuel appliance appliances or solid fuel
combustion appliances appliances appliances
Column C Column D
Column A Column B
1.Use the appropriate column to
estimate house infiltration 0.15 0.09 0.06 0.03
a)pressure factor
(cfm/sf)
b)conditioned floor area(sf)(including
unfinished basements)
Estimated House Infiltration(cfm):[la
x lb]
2.Exhaust Capacity
a)continuous exhaust-only ventilation
system(cfm);(not applicable to
balanced ventilation systems such as
HRV)
b)clothes dryer(cfm) 135 135 135 135
c)80%of largest exhaust rating(cfm);
Kitchen hood typically
(not applicable if recirculating system a�0
or if powered makeup air is electrically
interlocked and match to exhaust)
d)80%of next largest exhaust rating
(cfm); bath fan typically Not
(not applicable if recirculating system
or if powered makeup air is electrically Applicable "� V
interlocked and matched to exhaust)
Total Exhaust Capacity(cfm);
[2a+2b+2c+2d]
3.Makeup Air Quantity(cfm)
a)total exhaust capacity(from above) u'
b)estimated house infiltration(from 3 above)
Makeup Air Quantity(cfm);
[3a—3b]
(if value is negative,no makeup air is
needed)
4.For makeup Air Opening Sizing,
refer to Table 501.4.2
A. Use this column if there are other than fan-assisted or atmospherically vented gas or oil appliance or if there are no combustion appliances.(Power vent and
direct vent appliances may be used.)
B. Use this column if there is one fan-assisted appliance per venting system.(Appliances other than atmospherically vented appliances may also be Included.)
C. Use this column if there is one atmospherically vented(other than fan-assisted)gas or oil appliance per venting system or one solid fuel appliance.
D. Use this column if there are multiple atmospherically vented gas or oil appliances using a common vent or if there are atmospherically vented gas or oil
appliances and solid fuel appliances.
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