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Hersteller: Lifebreath Dateigröße: 1.05 mb Dateiname: ce1038bf-aab2-fc54-951e-e77f78f3c748.pdf Unterrichtssprache:

Excessive negative pressure may also cause the backdrafting of vented combustion equipment. Read the Application Warning on the front of this manual! Prior to balancing, ensure that: 1. All sealing of the ductwork system has been completed. 2. All of the HRV/ERV's components are in place and functioning properly. 3. Balancing dampers are fully open. 4. Unit is on HIGH speed. 5. Air flows in branch lines to specific areas of the house should be adjusted first prior to balancing the unit. A smoke pencil used at the grilles is a good indicator of each branch line's relative air flow. 6. After taking readings of both the stale air to the HRV/ERV duct and fresh air to the house duct, the duct with the lower CFM ([L/s] velocity) reading should be left alone, while the duct with the higher reading should be dampered back to match the lower reading. 7. Return unit to appropriate fan speed for normal operation BALANCING PROCEDURE The following is a method of field balancing an HRV/ERV using a Pitot tube, advantageous in situations when flow stations are not installed in the duct- work. Procedure should be performed with the HRV/ERV on high speed. The first step is to operate all mechanical systems on high speed, which have an influence on the ventilation system, i.e. the HRV/ERV itself and the forced air furnace or air handler if applicable. This will provide the maximum pressure that the HRV/ERV will need to overcome, and allow for a more accurate balance of the unit. Drill a small hole in the duct (about 3/16"), three feet downstream of any elbows or bends, and one foot upstream of any elbows or bends. These are recommended distances but the actual installation may limit the amount of straight duct. The Pitot tube should be connected to a magnehelic gauge or other manometer capable of reading from 0 to 0.25 in. (062 Pa) of water, preferably to 3 digits of resolution. The tube coming out of the top of the pitot is connected to the high pressure side of the gauge. The tube coming out of the side of the pitot is connected to the low pressure or reference side of the gauge. Insert the Pitot tube into the duct; pointing the tip into the airflow. For general balancing it is sufficient to move the pitot tube around in the duct and take an average or typical reading. Repeat this procedure in the other (supply or return) duct. Determine which duct has the highest airflow (highest reading on the gauge). Then damper that airflow back to match the lower reading from the other duct. 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 AIR FLOW Pitot Tube Air Flow Balancing Kit Pitot tube DUCT Magnehelic gauge c/w magnehelic gauge, Pitot tube, hose and carry case. PART NO. 99-167 25 Place pitot tube a minimum of 18" from blower or elbows Note: Duct connections may vary, depending on model. Outdoors MAGNEHELIC Pitot tube Magnehelic gauge MAGNEHELIC Magnehelic gauge Pitot tube Push and turn with slotted screwdriver. Damper automatically locks when pressure is released. When connecting ductwork to the collar, take note where screws are located. Screws should be located no further than 1/2” from outside edge of collar, so as not to impede operation of the damper. 1/2” Hard/Rigid ducting Insulated flexible ducting BALANCING COLLAR INSTRUCTIONS Installations where the HRV is ducted directly to the return of a furnace may require additional dampening on the fresh air to building duct. This is due to the high return static pressures found in some furnace installations. Push and turn with slotted screwdriver. Damper automatically locks when pressure is released. When connecting ductwork to the collar, take note where screws are located. Screws should be located no further than 1/2” from outside edge of collar, so as not to impede operation of the damper. 1/2” Hard/Rigid ducting Insulated flexible ducting BALANCING COLLAR INS...

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