9.32.3.6 — Ventilation Systems Coupled with Forced Air Heating Systems

(1) Where a heat recovery ventilator is installed to provide all or part of the requirements of this Subsection, this Article shall apply. (2) Heat recovery ventilators shall be designed to provide a minimum 55% sensible heat recovery efficiency when tested to the low temperature thermal and ventilation performance test method set out in CAN/CSA-C439, “Rating the Performance of Heat/Energy-Recovery Ventilators”, at a Station 1 test temperature of –25°C at an air flow not less than 30 L/s. (3) Where a heat recovery ventilator is connected to a forced air heating system, the supply side of the ventilator shall be directly connected to the return air side of the forced air heating system. (4) Two or more heat recovery ventilators shall not be connected in parallel air flow to a common air supply duct unless specifically recommended by the manufacturer. (5) Two or more heat recovery ventilators shall not be connected in parallel air flow to a common downstream exhaust duct. (6) Heat recovery ventilators installed in unheated spaces shall be installed so as to avoid condensation of moisture on fans and motors in exhaust air, in accordance with the manufacturer's instructions. (7) All start-up procedures recommended by the manufacturer including air balancing and air-flow determination shall be followed. (8) Free flow of condensate shall be provided in accordance with the manufacturer's recommendations or, in their absence, a condensate drain of minimum ½ inch nominal pipe size pitched in the direction of flow and complete with a trap or condensate pump with sufficient capacity shall be installed. (9) The heat recovery ventilator and all condensate lines shall be installed in a space where the ambient temperature will not adversely affect the operation of the system. (10) When operating at the rate required in Article 9.32.3.4., the supply and exhaust airflow rates of the heat recovery ventilator shall be balanced so that the value of the lesser flow shall be at least 90% of the value of the greater flow, unless otherwise recommended by the manufacturer.

(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. (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 outdoor 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 outdoor 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. (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.