When the outside air temperature drops below 23'F (-5°C), a defrost timer is activated which provides for an automatic defrost cycle every 17 minutes. During the automatic defrost cycle the fresh air supply is shut off for approximately 4.5 minutes while the exhaust fan continues to operate. This allows warm inside air to flow over the heat exchanger core melting any frost accumulation. After the defrost period, the fresh air supply fan automatically returns to the normal speed and fresh outside

In the balanced airflow system, the HRV exhaust removes stale room air (eg. from lunch room, storage or copy area) and returns to the space an equal amount of fresh outdoor air. Many buildings have a ceiling return air plenum as in Figure 4B. Fresh air from the HRV can be introduced directly into the ceiling space but this should occur near the air handler’s intake. By operating the HRV on a 24 hour/7 day battery backed timer the unit can be set to operate only when occupancy or indoor conditi

Avoid the use of undersized ducting and sharp radius bends and tees which can significantly increase the system pressure drop and reduce the air flows. NOTE: Fully insulated ducting with an integral vapour barrier must be used on all runs passing through unheated areas in order to avoid condensation problems and energy losses from the air streams. The four ports on the Model 700 AND 900 are designed to accept 8" X 14" (200 X 356 mm) and the Model 1200, 8" X 20“ (200 X 508 mm) hard duct for att

MODEL 700 DD - Supply bypass routes indoor air to defrost core. WEIGHT 64.4 kg (142 lbs.) SHIPPING WEIGHT 75.8 kg (167 lbs.) P IIF3 F © U Sffl /h i © AIRFLOWS (Each Air Stream) ^ 900(423) ä 800(378) E 700(329) £ 600(282) j 500(235) O 400(190) £ 300(143) < 200(94) 100(42) g 70%. Ul z UJ p 60% Ü UJ IL IL 111 50% LIFEi IREATt 700 HIGH St •EED MED SF EED LOWSf EED . - 5.5 5.0 •4.7 0.1(25) 0.2(50) 0

During the winter months the incoming cold fresh air is warmed by utilizing the heat recovered from the stale air before it is exhausted to the outdoors. During summer months when the indoor space is air conditioned, the Heat Recovery Ventilator will help in cooling the incoming fresh air with the stale air that is being exhausted. For Technical and Application Information Call NUTECH Service Dept. 519-457-1904 TABLE OF CONTENTS Engineering Data................................................

When this system is used the air handler's blower will constantly operate. The exhaust takeoff connection must be at least a meter from a directly connected HRV supply duct if both are connected to the same duct run. A damper located just prior to the HRV is required to balance the stale air exhausted with the fresh air supply entering the building. Return air suction points should be located at the opposite side of the room to the fresh air inlet. The inlets may be located in the ceiling or h