Bryant 581B036--072, 581C024--060 Damper Movement, Thermostats, Demand Controlled Ventilation DCV

To control the minimum damper position remotely, remove the factory-installed jumper on the P and P1 terminals on the EconoMi$er IV controller. Wire the field-supplied potentiometer to the P and P1 terminals on the EconoMi$er IV controller. (See Fig. 39.)

Damper Movement

Damper movement from full open to full closed (or vice versa) takes 21/2 minutes.

Thermostats

The EconoMi$er IV control works with conventional thermostats that have a Y1 (cool stage 1), Y2 (cool stage 2), W1 (heat stage 1), W2 (heat stage 2), and G (fan). The EconoMi$er IV control does not support space temperature sensors. Connections are made at the thermostat terminal connection board located in the main control box.

19

	18	LED ON
				D
	17
	16		LED OFF		LED ON
						C
	15
mA	14				LED OFF			LED ON
									B
	13
	12							LED OFF		LED ON
												A
	11
	10										LED OFF
	9												100
	40	45	50	55	60	65	70	75	80	85	90	95

DEGREES FAHRENHEIT

C06035

Fig. 36 ---Outside Air Temperature

Changeover Set Points

Occupancy Control

The factory default configuration for the EconoMi$er IV control is occupied mode. Occupied mode is provided by the black jumper from terminal TR to terminal N. When unoccupied mode is desired, install a field-supplied timeclock function in place of the jumper between TR and N. (See Fig. 29.) When the timeclock contacts are closed, the EconoMi$er IV control will be in occupied mode. When the timeclock contacts are open (removing the 24-v signal from terminal N), the EconoMi$er IV will be in unoccupied mode.

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.

Demand Controlled Ventilation (DCV)

When using the EconoMi$er IV for demand controlled ventilation, 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.

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 ventilation

581B,C

ECONOMI$ER IV

ECONOMI$ER IV CONTROLLER

GROMMET

required to remove contaminants during unoccupied periods. The following equation may be used to determine the percent of outside-air entering the building for a given damper position. For best results there should be at least a 10 degree difference in outside and return-air temperatures.

(TO x 100OA ) + (TR x 100RA ) =TM

RETURN AIR TEMPERATURE

SENSOR

RETURN DUCT (FIELD-PROVIDED)

C06036

Fig. 37 ---Return Air Temperature or Enthalpy

Sensor Mounting Location

TO = Outdoor-Air Temperature OA = Percent of Outdoor Air TR = Return-Air Temperature RA = Percent of Return Air TM = Mixed-Air Temperature

Once base ventilation has been determined, set the minimum damper position potentiometer to the correct position.

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