To determine the minimum position setting, perform the fol- lowing procedure:
1.Calculate the appropriate mixed air temperature using the following formula:
(TO x | OA | RA |
100 ) + (TR x | 100 ) = TM |
TO =
OA = Percent of Outdoor Air
TR =
RA = Percent of Return Air
TM =
As an example, if local codes require 10% outdoor air during occupied conditions,
(60 x .10) + (75 x .90) = 73.5 F
2.Disconnect the supply air sensor from terminals T and T1.
3.Ensure that the
4.Connect 24 vac across terminals TR and TR1.
5.Carefully adjust the minimum position potentiometer until the measured mixed air temperature matches the calculated value.
6.Reconnect the supply air sensor to terminals T and T1.
Remote control of the EconoMi$er IV damper is desirable when requiring additional temporary ventilation. If a field- supplied remote potentiometer (Honeywell part number S963B1128) is wired to the EconoMi$er IV controller, the minimum position of the damper can be controlled from a remote location.
To control the minimum damper position remotely, remove the
Damper Movement
Damper movement from full open to full closed (or vice versa) takes 21/2 minutes.
Thermostats
The EconoMi$er IV control works with conventional thermo- stats that have a Y1 (cool stage 1), Y2 (cool stage 2), W1 (heat stage 1), W2 (heat stage 2), and G (fan). The EconoMi$er IV control does not support space temperature sensors. Connections are made at the thermostat terminal connection board located in the main control box.
Occupancy Control
The factory default configuration for the EconoMi$er IV con- trol is occupied mode. Occupied status is provided by the black jumper from terminal TR to terminal N. When unoccu- pied mode is desired, install a
Demand Controlled Ventilation (DCV)
When using the EconoMi$er IV for demand controlled venti- lation, there are some equipment selection criteria which should be considered. When selecting the heat capacity and cool capacity of the equipment, the maximum ventilation rate must be evaluated for design conditions. The maximum damper position must be calculated to provide the desired fresh air.
Typically the maximum ventilation rate will be about 5 to 10% more than the typical cfm required per person, using normal outside air design criteria.
A proportional anticipatory strategy should be taken with the following conditions: a zone with a large area, varied occupancy, and equipment that cannot exceed the required ventilation rate at design conditions. Exceeding the required ventilation rate means the equipment can condition air at a maximum ventilation rate that is greater than the required ventilation rate for maximum occupancy. A proportional- anticipatory strategy will cause the fresh air supplied to increase as the room CO2 level increases even though the CO2 set point has not been reached. By the time the CO2 level reaches the set point, the damper will be at maximum ventilation and should maintain the set point.
In order to have the CO2 sensor control the economizer damper in this manner, first determine the damper voltage output for minimum or base ventilation. Base ventilation is the ventila- tion required to remove contaminants during unoccupied peri- ods. The following equation may be used to determine the percent of
| OA | RA |
(TO x | 100 ) + (TR x | 100 ) = TM |
TO =
OA = Percent of Outdoor Air
TR =
RA = Percent of Return Air
TM =
Once base ventilation has been determined, set the mini- mum damper position potentiometer to the correct position.
The same equation can be used to determine the occupied or maximum ventilation rate to the building. For example, an output of 3.6 volts to the actuator provides a base ventilation rate of 5% and an output of 6.7 volts provides the maximum ventilation rate of 20% (or base plus 15 cfm per person). Use Fig. 33 to determine the maximum setting of the CO2 sensor. For example, a 1100 ppm set point relates to a 15 cfm per person design. Use the 1100 ppm curve on Fig. 33 to find the point when the CO2 sensor output will be 6.7 volts. Line up the point on the graph with the left side of the chart to deter- mine that the range configuration for the CO2 sensor should be 1800 ppm. The EconoMi$er IV controller will output the
6.7volts from the CO2 sensor to the actuator when the CO2 concentration in the space is at 1100 ppm. The DCV set point may be left at 2 volts since the CO2 sensor voltage will be ignored by the EconoMi$er IV controller until it rises above the 3.6 volt setting of the minimum position potentiometer.
Once the fully occupied damper position has been deter- mined, set the maximum damper demand control ventilation potentiometer to this position. Do not set to the maximum position as this can result in