What is hot gas bypass in HVAC?

What is hot gas bypass in HVAC?

The hot gas bypass is a valve that automatically regulates the cooling temperature in the dryer exchanger based on the refrigerant pressure. The pressure measured after the heat exchanger directly correlates to the temperature in the system. A low pressure means there will be a low temperature.

How do you adjust a hot gas bypass?

HOT GAS BYPASS ADJUSTMENT By turning the adjustment stem one complete turn clockwise, the pressure setting will increase approximately 4 psig. By turning the adjustment stem counterclockwise one complete turn, the pressure setting will decrease approximately 4 psig.

Should hot gas bypass be insulated?

All suction line and hot gas bypass lines MUST be insulated.

Is hot gas bypass used for dehumidification?

By using a hot coil, you wring the water out on the evaporator coil and then reheat the air on that second coil, providing neutral dry air. A lot of people think the hot-gas reheat dehumidifies but it’s really the cooling coil doing the work.

For what purpose are hot gas bypass valves used?

The main purpose for adding Hot Gas Bypass (HGBP) to any system is to prevent condensate from freezing on the surface of the evaporator coil when the system is operating at extremely low load conditions.

How does bypass valve work?

Pressure bypass valves serve to control pressure in a system by diverting a portion of the flow. Typically they bypass fluid from the outlet of a pump back to the reservoir. A pressure bypass valve is essentially a back pressure regulator.

What is the effect of hot gas bypass method as a capacity control on compressor?

Using a hot gas bypass valve can also prevent short cycling of a compressor and prevent evaporator freezing in low load conditions. As a space or process temperature reaches set point, hot gas can be added to the evaporator to raise its temperature.

Why use a hot gas bypass?

Hot gas bypass can stabilize the system balance point by diverting hot, high-pressure refrigerant vapor from the discharge line directly to the low- pressure side of the system. This tactic reliable operation by introducing problems stemming from insufficient oil return and refrigerant logging in the HGBP line.

How does hot gas defrost work?

The hot gas defrost process uses the superheated vapor from the compressor discharge (on high pressure and high temperature) as the heat source. This vapor is diverted on a third system line, bypassing the condenser and the expansion valve, and directed through the unit cooler coil, warming it from the inside.

Is hot gas reheat the same as hot gas bypass?

Advances in HVAC controls and technology in HVAC systems over the years has made hot gas reheat very popular. HOT GAS BYPASS provides an artificial load on the evaporator by introducing a portion of high pressure, high temperature gas to the evaporator/suction side of the system.

What does hot gas reheat do?

The hot gas reheat feature is designed to control humidity at a specific level in the conditioned space. This is usually required when the outside temperature is cool and humid. It controls humidity without expending additional energy to reheat the cooled air.


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