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 – A 24V solenoid coil on the reversing valve controls heating cycle operation. Two thermostat options, one allowing “Auto” change over from cycle to cycle and the other constantly energizing solenoid coil during heating season and thus eliminating pressure equalization noise except during defrost, are to be used on “Auto” option, a circuit is completed for R-W1 and R-Y on each heating “on” cycle, energizing reversing valve solenoid and pulling in compressor contactor starting compressor and outdoor motor. R-G also makes starting indoor blower motor. Heat pump heating cycle now in operation.

The second option has no “Auto” change over position, but instead energizes the reversing valve solenoid constantly whenever the system switch on subbase is placed in “Heat” position, the “B” terminal being constantly energized from R. A thermostat demand for heat completes R-Y circuit, pulling in compressor contactor starting compressor and outdoor motor. R-G also make starting indoor blower motor.

High / Low Pressure control provides protection for the compressor. In the event system pressures go above 450 PSI or below 3.5 PSI in either cooling or heating 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.

The bypass timer should be set to 200 seconds and this is to assure there is no nuisance tripping of the low- pressure control during startup in heating mode under cold weather conditions. See Figure 22.

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 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.

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.

FIGURE 21

HEAT PUMP CONTROL BOARD (HPC)

Manual	2100-420H
Page	26 of 34

QH482, QH243, QH302, QH422, QH602 specifications

Bard has established itself as a leader in the heating, ventilation, and air conditioning (HVAC) industry with its innovative line of products, including the Bard QH series. Models such as QH362, QH602, QH422, QH302, and QH243 showcase the perfect blend of performance, efficiency, and advanced technology.

The Bard QH362 is built for both affordability and efficiency, making it ideal for smaller commercial spaces. This model offers a cooling capacity of 36,000 BTUs, providing optimal comfort with minimal energy consumption. Its robust design ensures long-lasting performance, while the air-cooled condenser enhances reliability in various climates.

The QH602 model takes it a step further with enhanced cooling capabilities, boasting a 60,000 BTU rating. This unit is particularly well-suited for larger commercial applications. Its advanced heat pump technology allows for efficient heating and cooling, ensuring indoor comfort year-round. The QH602 features a user-friendly control system that optimizes energy use and simplifies operation.

Next up, the QH422 model is designed for mid-sized commercial environments, offering 42,000 BTUs of cooling power. This model is distinguished by its energy-efficient design, significantly reducing operational costs while maintaining high-performance levels. The QH422 includes a smart thermostat that allows users to monitor and adjust settings remotely, further enhancing energy management.

The QH302 model is perfect for businesses looking for a balance between power and efficiency. With a capacity of 30,000 BTUs, this unit effectively meets the needs of medium-sized spaces. Its compact design allows for easy installation and maintenance, making it a favorite among commercial property managers.

Lastly, the QH243 model rounds out the series with a 24,000 BTU capacity, ideal for smaller commercial applications. This model showcases Bard's commitment to energy efficiency, equipped with environmentally friendly refrigerants and advanced insulation materials that minimize energy loss.

These Bard models feature innovative technologies such as variable-speed fans, which ensure consistent airflow regardless of outdoor conditions. Additionally, noise-reduction technologies provide a quieter operation, creating a more pleasant indoor environment.

In summary, the Bard QH series, including the QH362, QH602, QH422, QH302, and QH243, offers a comprehensive range of HVAC solutions tailored to diverse commercial needs. With their efficient designs, advanced technology, and focus on reliability, these models set the standard for modern heating and cooling equipment.