Bard Q24A1, Q30A1 Optional Climate Controls Sequence Of Operation, Pressure Service Ports

SEQUENCE OF OPERATION

Cooling – Circuit R-Y makes the thermostat pull in the compressor contactor starting the compressor and outdoor motor. The G (indoor motor) circuit is automatically completed on any call for cooling operation, or can be energized by manual fan switch on subbase for constant air circulation.

Heating – Circuit is completed for R-W1 on each heating “on” cycle, energizing the electric heat contactor. R-G also makes starting indoor blower motor.

Second stage heat – Energized circuit R-W2 and the electric heat contactor for the second bank of heaters (if equipped) is energized.

High / Low Pressure control provides protection for the compressor. In the advent system pressures go above 600 PSI or below 15 PSI in cooling mode the compressor will be stopped. This will activate the red light located in the control panel. The lockout circuit will hold compressor off line. When the system problem is corrected, the unit operation can be restored by turning of the main power supply off and then back on, or reset the room thermostat. The low pressure control has a bypass to eliminate nuisance lockout on cold start up. Factory set to 2 minutes.

FIGURE 23

CO2 CONTROLLER – FACTORY SET TO 1000

PPM

OPTIONAL CLIMATE CONTROLS SEQUENCE OF OPERATION

The Climate Control Option A is an electronic, non- programmable manual or auto changeover thermostat. The thermostat may be manually set to heat or cool mode. The thermostat will maintain the temperature set on the thermostat in the mode in which it is set.

The Climate Control Option D is an electronic, programmable thermostat. The thermostat can be set in the heat, cool or automatic mode. When the thermostat is sent in the heat mode, it can heat only to maintain the temperature set on the thermostat. When the thermostat is set in the cool mode, it can cool only to maintain the temperature set on the thermostat. When the thermostat is set in the automatic mode, the thermostat can change automatically to the heat or cool modes to maintain the temperature set on the thermostat.

The Climate Control Option “H” is an electronic, programmable thermostat and a CO2 controller. The thermostat can be set in the heat, cool or automatic mode. When the thermostat is set in the heat mode, it can heat only to maintain the temperature set on the thermostat. When the thermostat is set in the cool mode, it can cool only to maintain the temperature set on the thermostat. When the thermostat is set in the automatic mode, the thermostat can change automatically to the heat or cool modes to maintain the temperature set on the thermostat.

The CO2 controller will energize the vent option and the ID blower when the room CO2 levels rise over set level. Default CO2 set point is 1000 ppm. See Figure 23.

SW2SW1OUT AN

OFF ON OFF ON 0-100% 20-100% VOLTAGE CURRENT

"SW2" SET TO ON	"AN" SET TO VOLTAGE
"SW1" SET TO ON	"OUT" SET TO 20-100%

MIS-2667

PRESSURE SERVICE PORTS

High and low pressure service ports are installed on all units so that the system operating pressures can be observed. Pressure curves can be found later in the manual covering all models on both cooling and heating cycles. It is imperative to match the correct pressure curve to the unit by model number. Upper and lower service doors must be attached to obtain proper reading.

Manual	2100-522B
Page	34 of 38