Is hot gas bypass the same as hot gas reheat?

HOT GAS REHEAT uses the high pressure, high temperature, compressor discharge gas to reheat the air leaving the evaporator coil. 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.

How does reheat work in HVAC?

Reheat for dehumidification is simply cooling the air with the air conditioner to pull out the moisture. But instead of throwing the heat outside, the reheat coil simply puts that heat back Into the original air stream. It forces an air conditioner to act like a poorly designed dehumidifier.

How does a reheat system work?

Reheat is the addition of heat to previously cooled air. Reheat is used sometimes for humidity control, and sometimes for occupant comfort. In a VAV system, a damper modulates the amount of cool air supplied to the zone. As the zone cooling load decreases, the damper begins to close, supplying less cool air.

How does reheat control humidity?

To prevent the temperature of the dehumidified air from over-cooling the space, the reheat coil heats the air before it leaves the unit. As the compressor turns on and off, the humidity will also fluctuate; while the compressor is on, the air is dehumidified and the space humid- ity drops.

What is the difference between preheat and reheat?

As verbs the difference between reheat and preheat is that reheat is to heat something after it has cooled off, especially previously cooked food while preheat is to heat something in preparation for further action, especially cooking.

What is the purpose of a reheat coil when dehumidifying?

Removes moisture from the air via condensation, then utilizes a heating coil, either sourced by hot water or an electric reheat coil to raise the supply air temperature to lower the Relative Humidity of the air entering the spaces, drying the spaces out.

What is hot gas by pass?

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 does the hot gas reheat feature work?

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.

How much does a hot gas reheat unit cost?

Energy code limits the use of electric re-heat to 42,000 btu and below. With hot gas reheat, the average 5-ton unit sees a price increase between $2,800 and 3,000, rising significantly as the tonnage increases. If the space is cooling, it is de-humidifying, whether humidistat is calling or not.

Do you really need hot gas reheat in HVAC?

HVAC is not a one size fits all discipline.From a contractors stand point, we see the addition of hot gas reheat on the increase and the majority of the time justified. However one should stop and evaluate: do we really need this, or is it just insurance for a 3rd party?

How does hot gas reheat work in a intellipak?

Trane IntelliPak rooftop units now offer a hot gas reheat feature that recycles exhaust heat energy from the compressor to reduce indoor humidity while maintaining a comfortable air temperature (above and below). (Photos courtesy of Trane.) The hot gas reheat feature is designed to control humidity at a specific level in the conditioned space.