valutazioni - 3, GPA: 4.3 ( )

Produttore : Honeywell File Size : 630.92 kb File Nome : Lingua di insegnamento:

See section on DCV setpoint set up on page 4. 63-2569—04 8 W7340, W7345 COMMUNICATING ECONOMIZER LOGIC MODULES W7340, W7345 COMMUNICATING ECONOMIZER LOGIC MODULES On the W7340A and B models, the logic module as shipped from the factory, limits the minimum position setpoint to 50%. The logic module will not allow a minimum position greater than 50% open (from fully closed). NOTE: This setpoint limit can only be changed using a Modbus command. Equation 1. Formula to aid in minimum position adjustment. (TO . OA) + (TR . RA) = TM or (TO – TR). OA + TR = TM Where: TO = Outdoor air temperature OA = Percent of outdoor air TR = Return air temperature RA = Percent of return air TM = Resulting mixed air temperature NOTE: The following sample calculation uses only Fahrenheit temperature. EXAMPLE: Assume local codes require 10% outdoor air during occupied conditions, outdoor air is 60° F and return air is 75° F. Under these conditions, what is the temperature of the mixed air? (0.1x6° F) + (0.9x75° F) = 6.0° F + 67.5° F = 73.5° F or (60° F – 75° F ). 0.1 + 75° F = – 1.5 + 75° F = 73.5° F Mixed air will be 73.5° F when OA is 60° F and RA is 75° F with 10 percent outdoor air entering the building. NOTE: The W7340C model min position and DCV min must be set in the field by the installer. See Section DCV Min and Min Position Damper Set up. Enthalpy Changeover (W7340 only) Outdoor Enthalpy Changeover Setpoint (Single Enthalpy Changeover) The outdoor enthalpy changeover setpoint returns the outdoor air damper to minimum position when enthalpy rises above its setpoint. Enthalpy setpoint scale markings, located on the device, are A, B, C, D and E. See Fig. 10 for the corresponding control point. Differential Enthalpy Changeover Setting Differential enthalpy control uses: — W7340A and B use two C7400A Enthalpy Sensors connected to one logic module, or — Two 10K NTC temperature sensors and two C7600C Humidity Sensors connected to one logic module. — W7340C uses C7400C Enthalpy Sensor(s) or — Two 10K NTC temperature sensors and two C7600C Humidity Sensors connected to one logic module. With outdoor and return air sensors, the logic module compares outdoor air to return air instead of to a setpoint as it does for single enthalpy. The logic module selects the lower enthalpy air (return or outdoor) for cooling; for example, when outdoor air has lower enthalpy than return air, the outdoor air damper opens to bring in outdoor air for free cooling. NOTE: When using the W7340 for differential enthalpy, keep the setpoint potentiometer set at D. Exhaust Setpoint (W7340 only) The exhaust setpoint determines when the exhaust fan will run based on the damper position. The logic module, as shipped from the factory, uses an exhaust setpoint of 25%. When the damper position is greater than 25% open (from fully closed), relay contact for the exhaust fan is closed. When the damper position is below 22% open, the relay is de-energized. Control Configuration (W7340 only) The W7340 can be configured for humidity or enthalpy sensors. Configuration can be performed manually or over the Modbus. IMPORTANT If only a temperature sensor is connected to the W7340, the device will operate using dry bulb changeover control. To configure the W7340 manually: 1. Within the first three minutes after powering the device, short the external minimum damper position terminals (P-P1). NOTE: The LED will go solid within five seconds of shorting these terminals. 2. Maintaining the short for another five seconds causes the LED to flash quick pulses (between off periods) indicating the sensor configuration type: a. Two quick pulses: Humidity. b. Three quick pulses: Enthalpy. 3. To toggle the sensor configuration type: a. Remove the short until the LED goes solid again. b. Reapply the short for another five seconds. NOTE: Once the short is removed for over 10 seconds, the device saves the most recent configuration. 9 63-2569—04 W7340, W7345 COMMUNICATING ECONOMIZER LOGIC MODULES W7340, W7345 COMMUNICATING ECONOMIZER LOGIC MODULES (29) (32) (35) (38) (41) (43) CONTROL CURVE A B C D E CONTROL POINT APPROX. °F (°C) AT 50% RH 73 (23) 70 (21) 67 (19) 63 (17) 55 (13) 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 90100807060 50 40 30 20 10 ENTHALPY—BTU PER POUND DRYAIR 35 (2) 40 (4) 45 (7) 50 (10) 55 (13) 60 (16) 65 (18) 70 (21) 75 (24) 80 (27) A A B B C C D D RELATIVE HUMIDITY (%) 1 E E 35 40 45 50 55 60 65 70 75 80 85 90 95 100105110 (2) (4) (7) (10) (13) (16) (18) (21) (24) (27) (29) (32) (35) (38) (41) (43) APPROXIMATE DRY BULB TEMPERATURE— °F (°C) 1 HIGH LIMIT CURVE FOR W7210D, W7212, W7213, W7214, W7340B. M23879 Fig. 10. W7340 Performance Characteristics for Enthalpy Changeover Settings. Table 3. W7345 Performance Characteristics for Temperature Changeover Settings. Temperature Changeover Setting Approximate Control Point °F °C A 73 23 B 70 21 C 67 19 D 63 17 E 55 13 63-2569—04 10 W7340, W7345 COMMUNICATING ECONOMIZER LOGIC MODULES W7340, W7345 COMMUNICATING ECONOMI...

Scarica la tua

Per scaricare, digitare 2 cifre :