Assessments - 3, GPA: 4.3
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The flows should now be balanced. Actual airflow can be determined from the gauge reading. The value read on the gauge is called the velocity pressure. The Pitot tube comes with a chart that will give the air flow velocity based on the velocity pressure indicated by the gauge. This velocity will be in either feet per minute or metres per second. To determine the actual airflow, the velocity is multiplied by the cross sectional area of the duct being measured. This is an example for determining the airflow in a 6" duct. The Pitot tube reading was 0.025 inches of water. From the chart, this is 640 feet per minute. The 6" duct has a cross sectional area of = [3.14 x (6".12)2].4 = 0.2 square feet The airflow is then: 640 ft./min. X 0.2 square feet = 128 cfm For your convenience, the cross sectional area of some common round duct is listed below: DUCT DIAM. (inches) CROSS SECTION AREA (sq. ft.) 5 0.14 6 0.20 7 0.27 The accuracy of the air flow reading will be affected by how close to any elbows or bends the readings are taken. Accuracy can be increased by taking an average of multiple readings as outlined in the literature supplied with the Pitot tube. Pitot tube and gauge MAGNEHELIC DUCT AIR FLOW Pitot tube Magnehelic gauge Pitot Tube Air Flow Balancing Kit c/w magnehelic gauge, Pitot tube, hose and carry case. PART NO. 99-167 Place pitot tube a minimum of 18" from blower or elbows Note: Duct connections may vary, depending on model. Outdoors MAGNEHELIC Magnehelic gauge Pitot tube MAGNEHELIC Magnehelic gauge Pitot tube 14 The Integrated HVAC System WARNING: The 2500 is a quiet, efficient, low pressure system. Special care and attention should be given if connecting this unit to any other air handler that may draw more air than the 2500 is designed to accommodate. The HRV has become an integral component of the HVAC system. Figure 4 shows an HRV unit providing fresh air directly to the return air plenum of a Rooftop heat/cool unit. Many buildings have a ceiling return air plenum as in Figure 5. Fresh air from the HRV can be introduced directly into the ceiling space near the air handler’s intake. In installations where it is satisfactory to provide general exhaust from the space, the air to be exhausted may be taken directly from the return air plenum to the HRV as it is drawn back to the air handler. Fresh air supplied by the HRV is then introduced directly into the return air plenum but at a location closer to the air handler. The air handler would have a constant running blower to effectively distribute the fresh air and remove the stale air. Balancing dampers would be located in both the HRV supply and exhaust ducts between the return air plenum and the HRV. Electrical Connections System is 208/230V, 1 phase, 60 Hz. This unit meets all local codes and requirements. It is STRONGLY recommended that an electrical disconnect be installed prior to the HRV, and that it is turned off and locked out before servicing the unit. All electrical connections should be made by a qualified electrician. Two (2) knock-outs are provided. One is to be used for line voltage, and the other one for 24V control wires. Maintenance As with any mechanical system, a dedicated maintenance program will prolong the life of the equipment, and maintain its optimum performance. We recommend at least two (2) full inspections and cleanings per year under normal operating conditions, and more if circumstances warrant it. Service should include: • Cleaning of screens protecting outside hoods. • Cleaning of core. To access core, remove service panels and slide core halfway out. Wash core protruding from cabinet with water and/or a mild cleaning solution. Push core through to the other side of the cabinet and repeat procedure to clean the other side of the core. In many cases, only a vacuuming of the core surface is required. • Inspect filters and replace as necessary. • Wipe down drain pans and inside of cabinet, using a mild disinfectant. • Ensure condensate drain has free flow of moisture. • Inspect blowers and electrical panel. • Confirm operation. 15 The Integrated HVAC System Check design static pressure of air handler to ensure it is compatible with HRV ROOFTOP HEAT/COOL UNIT DAMPERS OR ADJUSTABLE GRILLES BALANCING DAMPERS HRV UNIT EXHAUST TO HRV SUPPLY DUCT RETURN AIR DUCT FRESH AIR SUPPLY FRESH AIR TO BUILDING STALE AIR EXHAUST B A Figure 4 ROOFTOP HEAT/COOL UNIT SUPPLY DUCTWORKCEILING RETURN AIR PLENUM ROOF DECK STALE AIR EXHAUST HRV FRESH AIR SUPPLY HRV UNIT FRESH AIR INTAKE STALE AIR EXHAUST DUCT B A BALANCING DAMPERS Figure 5 BALANCING DAMPERS A - Fresh Air Supply B - Stale Air Exhaust 16 2500 WIRING DIAGRAM SNAP DISK ON/OFF HIGH/LOW COMMON 240 VAC C1 HIGH BLACK - HIGHYELLOW - COMBLUE - MIDRED - LOW SUPPLY MOTOR SUPPLY BROWN BROWN CAP C2 F2 L1 L2 F3 MAX 15A MAX 15A LOW TIMER ON/OFF 24V F1 XFRM1 240V COMMON HIGH/LOW C3 HIGH BLACK - HIGHYELLOW - COMBLUE - MIDRED - LOW EXHAUST MOTOR BROWN BROWN CAP EXHAUST C4 LOW R1 R2 R3 R4 T2 T3 T4 T5 ...
Este manual também é adequado para os modelos :Fans - 2500IFD (289.69 kb)