The Ontario Building Code | Principal Exhaust
9.32.3.4. Principal Exhaust
(1) A principal exhaust fan shall be installed and shall be rated to provide not less than the capacity given in Table 9.32.3.4.A.
Table 9.32.3.4.A.
Principal Exhaust Fan Capacity
Forming Part of Sentence 9.32.3.4.(1)
| Item | Column 1 Number of Bedrooms in Dwelling Unit | Column 2 Capacity, L/s |
| 1. | 1 | 15 |
| 2. | 2 | 22.5 |
| 3. | 3 | 30 |
| 4. | 4 | 37.5 |
| 5. | 5 | 45 |
| 6. | More than 5 | System must comply with Sentence 6.2.1.1.(1) |
(2) Except as permitted in Sentence (3), the principal exhaust fan shall be controlled by a manual switch.
(3) A principal exhaust fan required under this Article may be controlled by a dehumidistat or other automatic control device where the manual switch required in Sentence (2) is capable of activating the fan regardless of the setting of the automatic control.
(4) The switches required in Sentences (2) and (3) shall be centrally located in the dwelling unit and shall be identified with the words ventILATION FAN.
(5) The principal exhaust required in this Article may be provided by means of a heat recovery ventilator installed in accordance with Article 9.32.3.11.
(6) Where the installed capacity of the principal exhaust fan exceeds the minimum capacity required in Sentence (1) by more than 50%, the control required in Sentence (2) shall include provision to allow reduction of the flow to within ±10% of the minimum capacity specified in Sentence (1).
(7) Where an exhaust air intake for the principal exhaust fan is connected directly to the duct system of a forced air heating system or other central air circulating system, it shall,
(a) be connected to the return air side of the system, and
(b) be connected not less than 1 000 mm upstream from any outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">door air supply duct.
(8) Where an exhaust air intake for the principal exhaust fan is located in the kitchen, it shall be located in the ceiling or on the wall within 300 mm of the ceiling.
(9) Single or multiple exhaust ducts serving the principal exhaust fan required by Sentence (1) shall be sized according to Part 6 except that they may be sized according to Table 9.32.3.4.B. where,
(a) the longest total duct length, from intake grille to outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">door hood, does not exceed 12 m, and
(b) the number of elbows does not exceed 4,
but, in any case, they shall not be smaller than recommended by the manufacturer of the fan.
Table 9.32.3.4.B.
Principal Exhaust Duct Size
Forming Part of Sentences 9.32.3.4.(9) and (10)
| Item | Column 1 | Column 2 | Column 3 | Column 4 | Column 5 |
|
| Number of Bedrooms in Dwelling Unit | Minimum Exhaust Duct Diameter |
|
| |
|
|
| Ducts Connected to Inlet and outlet of Principal Exhaust Fan | Ducts Connected to One Side Only of Principal Exhaust Fan | ||
|
|
| Smooth Duct, mm | Flexible Duct, mm | Smooth Duct, mm | Flexible Duct, mm |
| 1. | 1 | 100 | 125 | 100 | 125 |
| 2. | 2 | 125 | 150 | 125 | 150 |
| 3. | 3 | 125 | 150 | 150 | 175 |
| 4. | 4 | 150 | 175 | 150 | 175 |
| 5. | 5 | 150 | 175 | 150 | 175 |
| 6. | More than 5 | Part 6 design | Part 6 design | Part 6 design | Part 6 design |
(10) In applying Table 9.32.3.4.B.,
(a) where there is more than one exhaust air inlet duct connected directly to the fan, the diameter of the inlet ducts may be decreased by 25 mm, and
(b) where the exhaust duct is connected to the duct system of a forced air heating system, the duct diameter shall be increased by 25 mm.