As soon as the defrost cycle kicks in, remove the shorting instrument from the SPEEDUP terminals. Otherwise the timing will remain accelerated and run through the 10-minute maximum defrost length sequence in a matter of seconds and will automatically terminate the defrost sequence.

There is an initial defrost (SEN JMP) jumper on the control that can be used at any outdoor ambient during the heating cycle to simulate a 0° coil temperature. This can be used to check defrost operation of the unit without waiting for the outdoor ambient to fall into the defrost region.

The jumper connection (SEN JMP) on the heat Pump Control (HPC) that can be used during the heating cycle to simulate a 0 degree coil condition and initiate the defrost sequence. By placing a jumper across the SEN JMP terminals (1/4 inch QC terminal works best) the defrost sensor mounted on the outdoor coil is shunted out and will activate the timing circuit. This permits the defrost cycle to be checked out in warmer weather conditions without the outdoor temperature having to fall into the defrost region.

There are three time settings on the HPC — 30, 60 or on minutes. These are elapsed run-time values, and the outdoor coil temperature sensor must be below the 30 degree equivalent resistance value for the timer to accumulate time towards the actual defrost cycle event. Using the SEN JMP terminals will force the timer to run continuously.

The next event is the actual defrost cycle when the reversing valve shifts the refrigerant system back to the cooling mode, and the outdoor fan motor is turned off to speed the heating of the outdoor coil and melting of any accumulated frost. The SPEEDUP terminals can be used to reduce the 30,60 or 90 minute real-time periods to a matter of seconds. Electric heat is typically turned on to temper the supply air temperature being delivered into the building during the defrost cycle.

There is also a 5-minute compressor time delay function built into the HPC. This is to protect the compressor from short cycling conditions. In some instances it is helpful to the service technician to override or speedup this timing period, and shorting out the SPEEDUP terminals for a few seconds can do this.

FIGURE 10

DEFROST CONTROL BOARD

Manual 2100-399 Page 16

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Bard WH602, WH483, WH421 installation instructions Defrost Control Board
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WH421, WH483, WH602 specifications

Bard WH602, WH421, and WH482 are distinguished models in Bard's line of high-performance wall-mounted heaters. Each unit is designed to offer reliable heating solutions for various commercial and industrial applications. These models are renowned for their energy efficiency, robust construction, and ease of use, making them ideal for a variety of environments, including warehouses, manufacturing facilities, and other large spaces.

The WH602 model boasts impressive heating capabilities, featuring a powerful fan-forced heater equipped with a 60000 BTU rating. This allows it to effectively heat large areas quickly and efficiently. One of its main features is the high-efficiency, stainless steel heat exchanger that promotes better heat transfer, enhancing the overall performance and longevity of the heater. The WH602 is designed with energy-saving technology, allowing it to operate with minimal electricity consumption while maximizing output.

The WH421 model offers a more compact solution without sacrificing power. With a heating capacity of 42000 BTU, it is suitable for medium-sized spaces. Like the WH602, the WH421 utilizes a stainless steel heat exchanger, ensuring durability and efficient heating. This model is equipped with a quiet, high-performance fan that distributes heat uniformly throughout the space, maintaining comfortable conditions without the distraction of excessive noise. Its compact design also allows for easy installation in tighter spaces.

The WH482 is a versatile model that falls between the two in terms of performance and application. Rated at 48000 BTU, it combines the benefits of both the WH602 and WH421, making it suitable for various heating demands. The WH482 features advanced control options, allowing users to set specific heating schedules and temperatures for improved comfort and energy efficiency. Additionally, it has built-in safety features like over-temperature protection and a thermal cutoff switch, ensuring safe operation in commercial environments.

All three models share key characteristics, including a robust construction built to withstand harsh conditions, user-friendly controls, and compliance with industry safety standards. Their wall-mounted design saves valuable floor space while providing powerful heating performance. Overall, Bard WH602, WH421, and WH482 represent a commitment to quality, performance, and customer satisfaction, making them top choices for businesses seeking efficient heating solutions.
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