CITY OF EDINA
4801 50
th
Street West, Edina, MN 55424-1394
Building Inspections Department
(952) 826-0372 FAX (952) 826-0389 EdinaMN.gov
Vent
ilation, Makeup and Combustion
Air Calculations Submittal Form for New Dwellings
These blank submittal forms and instructions are available on the City of Edina website. The completed form must be submitted at the
time of application for a building and mechanical permit for new construction. Additional forms may be downloaded and printed HERE.
Site Address
Date
Contractor
Completed By (please print)
Signature
Section A
Ventilation Quantity
(Determine quantity by using Table R403.5.2 or Equation R403.5.2)
Square feet (Conditioned area including
Basement finished or unfinished)
Number of bedrooms
Total required ventilation
Continuous ventilation
Directions - Determine the total and continuous ventilation rate by either using Table R403.5.2 or equation R403.5.2.
The table and equation are below.
Table R403.5.2
Total and Continuous Ventilation Rates (in cfm)
Number of Bedrooms
2
3
4
5
6
Conditioned space
(in sq. ft.)
Total/
continuous
Total/
continuous
Total/
continuous
Total/
continuous
Total/
continuous
1000-1500
75/40
90/45
105/53
120/60
135/68
1501-2000
85/43
100/50
115/58
130/65
145/73
2001-2500
95/48
110/55
1
25/63
140/70
155/78
2501-3000
105/53
120/60
135/68
150/75
165/83
3001-3500
115/58
130/65
145/73
160/80
175/88
3501-4000
125/63
140/70
155/78
170/85
185/93
4001-4500
135/68
150/75
165/83
180/90
195/98
4501-5000
145/73
160/80
175/88
190/95
205/103
5001-5500
155/78
170/85
185/93
200/100
215/108
5501-6000
165/83
180/90
195/98
210/105
225/113
Equation R403.5.2
(0.02 x square feet of conditioned space) + [15 x (number of bedrooms + 1)] = Total ventilation rate (cfm)
Total ventilation The mechanical ventilation system shall provide sufficient outdoor air to equal the total ventilation rate
average, for each one-hour period according to the above table or equation. For heat recovery ventilators (HRV) and energy
recovery ventilators (ERV) the average hourly ventilation capacity must be determined in consideration of any reduction of
exhaust or out outdoor air intake, or both, for defrost or other equipment cycling.
Continuous ventilation - A minimum of 50 percent of the total ventilation rate, but not less than 40 cfm, shall be provided,
on a continuous rate average for each one-hour period. The portion of the mechanical ventilation system intended to be
continuous may have automatic cycling controls providing the average flow rate for each hour is met.
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Page 2 of 6
Section B
Ventilation Method
Balanced, HRV (Heat Recovery Ventilator) or ERV (Energy Recovery
Ventilator) cfm of unit in low must not exceed continuous
ventilation rating by more than 100%.
Low CFM High CFM
Directions - Balanced ventilation systems are typically HRV or ERV’s. Enter the low and high cfm amounts. Low cfm air flow
must be equal to or greater than the required continuous ventilation rate and less than 100% greater than the continuous rate.
(For instance, if the low cfm is 40 cfm, the ventilation fan must not exceed 80 cfm.) Automatic controls may allow the use of a
larger fan that is operated a percentage of each hour.
Section C
Ventilation Fan Schedule
Description
Location
Continuous
Intermittent
Directions - The ventilation fan schedule should describe what the fan is for, the location, cfm, and whether it is used for
continuous or intermittent ventilation. The fan that is chose for continuous ventilation must be equal to or greater than the
low cfm air rating and less than 100% greater than the continuous rate. (For instance, if the low cfm is 40 cfm, the continuous
ventilation fan must not exceed 80 cfm.) Automatic controls may allow the use of a larger fan that is operated a percentage of
each hour.
Section D
Ventilation Controls
(Describe operation and control of the continuous and intermittent ventilation)
Directions - Describe the operation of the ventilation system. There should be adequate detail for plan reviewers and inspectors to verify
design and installation compliance. Related trades also need adequate detail for placement of controls and proper operation of the building
ventilation. If exhaust fans are used for building ventilation, describe the operation and location of any controls, indicators and legends. If
an ERV or HRV is to be installed, describe how it will be installed. If it will be connected and interfaced with the air handling equipment,
please describe such connections as detailed in the manufactures’ installation instructions. If the installation instructions require or
recommend the equipment to be interlocked with the air handling equipment for proper operation, such interconnection shall be made and
described.
Section E
Make-up air
Passive (determined from calculations from Table 501.41)
Powered (determined from calculations from Table 501.4.1)
Interlocked with exhaust device (determined from calculation from Table 501.4.1)
Other, describe:
Location of duct or system ventilation make-up air:
Determined from make-up air opening table
Cfm
Size and type (round, rectangular, flex or rigid)
(NR means not required)
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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
vent or direct vent
appliances or no
combustion appliances
Column A
One or multiple fan-
assisted appliances and
power vent or direct vent
appliances
Column B
One atmospherically vent
gas or oil appliance or
one solid fuel appliance
Col
umn C
Multiple atmospherically
vented gas or oil
appliances or solid fuel
appliances
Column D
1. Use the appropriate column to
estimate house infiltration
a) pressure factor
(cfm/sf)
0.15 0.09 0.06 0.03
b) conditioned floor area (sf) (including
unfinished basements)
Estimated House Infiltration (cfm): [1a
x 1b]
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
or if powered makeup air is electrically
interlocked and match to exhaust)
d) 80% of next largest exhaust rating
(cfm); bath fan typically
(not applicable if recirculating system
or if powered makeup air is electrically
interlocked and matched to exhaust)
Not
Applicable
Total Exhaust Capacity (cfm);
[2a + 2b +2c + 2d]
3. Makeup Air Quantity (cfm)
a) total exhaust capacity (from above)
b) estimated house infiltration (from
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.
1
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Makeup Air Opening Table for New and Existing Dwelling
Table 501.4.2
One or multiple power
vent, direct vent
appliances, or no
combustion appliances
Column A
One or multiple fan-
assisted appliances and
power vent or direct
vent appliances
Column B
One atmospherically
vented gas or oil
appliance or one solid
fuel appliance
Column C
Multiple atmospherically
vented gas or oil
appliances or solid fuel
appliances
Column D
Duct diameter
Passive opening
1 36
1 22
1 15
1 – 9
3
Passive opening
37 66
23 41
16 28
10 17
4
Passive opening
67 109
42 66
29 46
18 28
5
Passive opening
110 - 163
67 100
47 69
29 42
6
Passive opening
164 232
101 143
70 99
43 61
7
Passive opening
233 317
144 195
100 135
62 83
8
Passive opening
w/motorized damper
318 419
196 258
136 179
84 110
9
Passive opening
w/motorized damper
420 539
259 332
180 230
111 142
10
Passive opening
w/motorized damper
540 679
333 419
231 290
143 179
11
Powered makeup air
>679
>419
>290
>179
NA
Notes:
A. An equivalent length of 100 feet of round smooth metal duct is assumed. Subtract 40 feet for the exterior hood and ten feet for each 90- degree elbow to
determine the remaining length of straight duct allowable.
B. If flexible duct is used, increase the duct diameter by one inch. Flexible duct shall be stretched with minimal sags. Compressed duct shall not be accepted.
C. Barometric dampers are prohibited in passive makeup air openings when any atmospherically vented appliance is installed.
D. Powered makeup air shall be electrically interlocked with the largest exhaust system.
Section F
Combustion air
Not required per mechanical code (No atmospheric or power vented appliances)
Passive (see IFGC Appendix E, Worksheet E-1)
Other, describe:
Explanation - If no atmospheric or power vented appliances are installed, check the appropriate box, not required. If a power
vented or atmospherically vented appliance installed, use IFGC Appendix E, Worksheet E-1 (see below). Please enter size and type.
Combustion air vent supplies must communicate with the appliance or appliances that require the combustion air.
Sect
ion F calculations follow on the next 2 pages.
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Directions - The Minnesota Fuel Gas Code method to calculate to size of a required combustion air opening, is called the Known Air
Infiltration Rate Method. For new construction, 4b of step 4 is required to be filled out.
IFGC Appendix E, Worksheet E-1, 1346.6012
Residential Combustion Air Calculation Method
(for Furnace, Boiler, and/or Water Heater in the Same Space)
Step 1: Complete vented combustion appliance information.
Furnace/Boiler:
__ Draft Hood __ Fan Assisted Direct Vent Input: Btu/hr
or Power Vent
Water Heater:
__ Draft Hood Fan Assisted __ Direct Vent Input: Btu/hr
or Power Vent
Step 2: Calculate the volume of the Combustion Appliance Space (CAS) containing combustion appliances.
The CAS includes all spaces connected to one another by code compliant openings. CAS volume: ft
3
L x W x H L W H
Step 3: Determine Air Changes per Hour (ACH)1
Default ACH values have been incorporated into Table E-1 for use with Method 4b (KAIR Method).
If the year of construction or ACH is not known, use method 4a (Standard Method).
Step 4: Determine Required Volume for Combustion Air. (DO NOT COUNT DIRECT VENT APPLIANCES)
4a.
Standard Method
Total Btu/hr input of all combustion appliances Input: ______________ Btu/hr
Use Standard Method column in Table E-1 to find Total Required TRV: _________________ ft
3
Volume (TRV)
If CAS Volume (from Step 2) is greater than TRV then no outdoor openings are needed.
If CAS Volume (from Step 2) is less than TRV then go to STEP 5.
4b. Known Air Infiltration Rate (KAIR) Method (DO NOT COUNT DIRECT VENT APPLIANCES)
Total Btu/hr input of all fan-assisted and power vent appliances Input: Btu/hr
Use Fan-Assisted Appliances column in Table E-1 to find RVFA: ft
3
Required Volume Fan Assisted (RVFA)
Total Btu/hr input of all Natural draft appliances Input: Btu/hr
Use Natural draft Appliances column in Table E-1 to find RVNFA: ft
3
Required Volume Natural draft appliances (RVNDA)
Total Required Volume (TRV) = RVFA + RVNDA TRV = + = TRV ft
3
If C
AS Volume (from Step 2) is greater than TRV then no outdoor openings are needed.
If CAS Volume (from Step 2) is less than TRV then go to STEP 5.
Step 5: Calculate the ratio of available interior volume to the total required volume.
Ratio = CAS Volume (from Step 2) divided by TRV (from Step 4a or Step 4b)
Ratio = / =
Step 6: Calculate Reduction Factor (RF).
RF = 1 minus Ratio RF = 1 - =
Step 7: Calculate single outdoor opening as if all combustion air is from outside.
Total Btu/hr input of all Combustion Appliances in the same CAS Input: Btu/hr
(EXCEPT DIRECT VENT)
Comb
ustion Air Opening Area (CAOA):
Total Btu/hr divided by 3000 Btu/hr per in
2
CAOA = / 3000 Btu/hr per in
2
= in
2
Step 8: Calculate Minimum CAOA.
Minimum CAOA = CAOA multiplied by RF Minimum CAOA = x = in
2
Step 9: Calculate Combustion Air Opening Diameter (CAOD)
CAOD = 1.13 multiplied by the square root of Minimum CAOA CAOD = 1.13 √ Minimum CAOA = in. diameter
go up one inch in size if using flex duct
1 If desired, ACH can be determined using ASHRAE calculation or blower door test. Follow procedures in Section G304.
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IFGC Appendix E, Table E-1
Residential Combustion air (Required Interior Volume Based on Input Rating of Appliance)
Input Rating
(Btu/hr)
Standard Method
Known Air Infiltration Rate (KAIR) Method (cu ft)
Fan Assisted or Power Vent
Natural Draft
1994 to present
Pre-1994
1994 to present
Pre-1994
5,000
250
375
188
525
263
10,000
500
750
375
1,050
525
15,000
750
1,125
563
1,575
788
20,000
1,000
1,500
750
2,100
1,050
25,000
1,250
1,875
938
2,625
1,313
30,000
1,500
2,250
1,125
3,150
1,575
35,000
1,750
2,625
1,313
3,675
1,838
40,000
2,000
3,000
1,500
4,200
2,100
45,000
2,250
3,375
1,688
4,725
2,363
50,000
2,500
3,750
1,675
5,250
2,625
55,000
2,750
4,125
2,063
5,775
2,888
60,000
3,000
4,500
2,250
6,300
3,150
65,000
3,250
4,875
2,438
6,825
3,413
70,000
3,500
5,250
2,625
7,350
3,675
75,000
3,750
5,625
2,813
7,875
3,938
80,000
4,000
6,000
3,000
8,400
4,200
85,000
4,250
6,375
3,188
8,925
4,463
90,000
4,500
6,750
3,375
9,450
4,725
95,000
4,750
7,125
3,563
9,975
4,988
100,000
5,000
7,500
3,750
10,500
5,250
105,000
5,250
7,875
3,938
11,025
5,513
110,000
5,500
8,250
4,125
11,550
5,775
115,000
5,750
8.625
4,313
12,075
6,038
120,000
6,000
9,000
4,500
12,600
6,300
125,000
6,250
9,375
4,688
13,125
6,563
130,000
6,500
9,750
4,875
13,650
6,825
135,000
6,750
10,125
5,063
14,175
7,088
140,000
7,000
10,500
5,250
14,700
7,350
145,000
7,250
10,875
5,438
15,225
7,613
150,000
7,500
11,250
5,625
15,750
7,875
155,000
7,750
11,625
5,813
16,275
8,138
160,000
8,000
12,000
6,000
16,800
8,400
165,000
8,250
12,375
6,188
17,325
8,663
170,000
8,500
12,750
6,375
17,850
8,925
175,000
8,750
13,125
6,563
18,375
9,188
180,000
9,000
13,500
6,750
18,900
9,450
185,000
9,250
13,875
6,938
19,425
9,713
190,000
9,500
14,250
7,125
19,950
9,975
195,000
9,750
14,625
7,313
20,475
10,238
200,000
10,000
15,000
7,500
21,000
10,500
205,000
10,250
15,375
7,688
21,525
10,783
210,000
10,500
15,750
7,875
22,050
11,025
215,000
10,750
16,125
8,063
22,575
11,288
220,000
11,000
16,500
8,250
23,100
11,550
225,000
11,250
16,875
8,438
23,625
11,813
230,000
11,500
17,250
8,625
24,150
12,075
1. The
1994 date refers to dwellings constructed under the 1994 Minnesota Energy Code. The default KAIR used in this section of the table is
0.20 ACH.
2. This section of the table is to be used for dwellings constructed prior to 1994. The default KAIR used in this section of the table is 0.40 ACH.