Supermarket DX Motor Room Walkaround

The remote headers for each rack are placed along the motor room walls, not within or immediately beside the racks. Each rack has multiple compressors that discharge compressed vapor into a single common discharge line. The discharge line leads to the oil separator, and then it leads to the heat reclaim or condenser.

The oil separator has an oil line that leads to the oil reservoir. The reservoir stores oil until that oil needs to make its way back to the compressors. Then, the oil passes through an oil filter and heads to the compressor. Each compressor has an oil regulator with a sight glass to ensure proper oil feeding.

Stemming from the discharge line on rack 5, there is a smaller line for hot gas defrost. However, the defrost isn’t used on that rack.

In this particular system, the air conditioner’s heat reclaim is a reheat coil, which also helps with dehumidification. Then, another line leads back to the rack and forces the refrigerant through a check valve, which leads to the condenser. On the second rack (rack 4), half of the condenser has been eliminated, which we can see on the piping and when we go outside.

From the condenser, you will find two liquid lines with check valves. In some cases, a rack will have a condenser split valve, but the rack in the video does not have one. The refrigerant in the liquid line goes to the receiver (with a liquid level indicator) and then the filter-drier. Once the refrigerant passes through the drier, it travels all the way to the remote header, where the liquid header is. The suction header is on that same remote header and may not have a suction drier.

Each evaporator has an electronic EPR valve to throttle the suction pressure and maximize runtime. Those valves close during defrost. Then, the suction header extends all the way back to the rack and the compressors on it.

The other rack has a defrost differential valve. That valve creates a pressure differential to establish the flow of hot gas through the defrost header (on the remote header) and up the liquid line.

On this equipment, the compressor contactors are behind a panel on the rack itself, and each contactor has its own control breaker. The controller is also on a panel on the rack. You will find the relay board behind that controller

The defrost board is behind a panel on one of the remote headers. The schematics are behind that same panel.

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