LOW Voltage Connections

These units use a grounded 24 volt AC low voltage circuit.

The “R” terminal is the hot terminal and the “C” terminal is grounded.

“G” terminal or pins 6 and 1 of P2 are the fan inputs. Both must be energized for proper fan operation. This is done automatically in the factory installed climate control options. If the climate control option is abandoned and connections are made directly to P2 both pins 6 and 1 of P2 must be energized for proper operation.

“Y” terminal or pin 7 of P2 is the compressor input.

“B” terminal or pin 8 of P2 is the reversing valve input. The reversing valve must be energized for heating mode.

“R” terminal or pin 10 of P2 is 24 VAC hot.

“C” terminal or pin 11 of P2 is 24 VAC grounded.

“L” terminal or pin 12 of P2 is compressor lockout output. This terminal is activated on a high or low pressure trip by the electronic heat pump control. This is a 24 VAC output.

“W2” terminal or pin 9 of P2 is second stage heat (if equipped). If the unit is equipped with an optional hot water coil plenum box or electric heat these will be energized by this terminal.

“O1” terminal of pin 5 of P2 is the ventilation input. This terminal energizes any factory installed ventilation option.

“E” terminal or pin 3 of P2 is the emergency heat input. This terminal energizes the emergency heat relay.

NOTE: For total and proper control using DDC, a total of 6 controlled outputs are required (5 if no ventilation system is installed). For proper system operation under Emergency Heat conditions. Where the compressor needs to be deactivated, the B-W2-E outputs need to be energized. Removing the Y (compressor) signal alone turns the compressor off, but does not activate the additional circuitry embedded in the heat pump for proper and complete operation.

LOW VOLTAGE CONNECTIONS FOR

DDC CONTROL

Fan Only	Energize G
Cooling Mode	Energize Y, G
Heat Pump Heating	Energize Y, G, B
2nd Stage Heating	Energize G, W2
(if employed)
Ventilation	Energize G, O1
Emergency Heat	Energize B, W2, E

GENERAL

This unit is equipped with a variable speed ECM motor. The motor is designed to maintain rated airflow up to the maximum static allowed. It is important that the blower motor plugs are not plugged in or unplugged while the power is on. Failure to remove power prior to unplugging or plugging in the motor could result in motor failure.

CAUTION

Do not plug in or unplug blower motor connectors while the power is on. Failure to do so may result in motor failure.

Manual	2100-420H
Page	16 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.