12.3.4.4.

(1) A heating, ventilating and air-conditioning system that serves more than one heating, ventilating and air-conditioning zone shall conform to Clauses 12.2.1.1.(2)(a)v1v2 or (b).

(2) Sentences (3) to (11) and Article 12.3.4.5. apply to a heating, ventilating and air-conditioning system that serves a single heating, ventilating and air-conditioning zone.

(3) The energy efficiency of equipment in a heating, ventilating and air-conditioning system that serves a single heating, ventilating and air-conditioning zone shall conform to Supplementary Standard SB-10.

(4) An air-conditioning system with a cooling capacity of 40 kW or more shall have an economizer,

(a) controlled by appropriate high limit shut-off control, and

(b) equipped with either barometric or powered relief sized to prevent excess pressurization of the building.

(5) Outdoor air dampers for economizer use shall be provided with blade and jamb seals.

(6) A heat recovery ventilator with a recovery effectiveness of 50% or more at the outside winter design temperature shall be provided where the quantity of the outdoor air supplied to the air duct distribution system is,

(a) more than 1 400 L/s, and

(b) more than 70% of the supply air quantity of the system.

(7) Where a heat recovery ventilator is installed, the system shall have provisions to bypass or control the heat recovery ventilator to permit operation of the air economizer.

(8) A heating, ventilating and air-conditioning system shall be controlled by a manual changeover or dual setpoint thermostat.

(9) Except for a system requiring continuous operation, a heating, ventilating and air-conditioning system that has a cooling or heating capacity greater than 4.4 kW and a supply fan motor rated for more than 0.5 kW shall be provided with a time clock that,

(a) is capable of starting and stopping the system under different schedules for seven different day-types per week,

(b) is capable of retaining programming and time setting during a loss of power for a period of 10 hours or more,

(c) includes an accessible manual override that allows temporary operation of the system for up to two hours,

(d) is capable of temperature setback down to 13°C during off-hours, and

(e) is capable of temperature setup to 32°C during off-hours.

(10) Where separate heating and cooling equipment serves the same temperature zone, thermostats shall be interlocked to prevent simultaneous heating and cooling.

(11) A heating, ventilating and air-conditioning system with a design supply air capacity greater than 5000 L/s shall have optimum start controls