Indoor air quality (IAQ) and occupant comfort are two of the most important factors for any HVAC system design.

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One of the leading causes of poor IAQ and occupant discomfort is too much moisture in the air, commonly referred to as high humidity. IAQ problems associated with high humidity include mold growth, condensation, increased sickness, and allergic reactions. As for occupant comfort, the saying goes, “It’s not the heat; it’s the humidity.”

Improving indoor air quality and occupant comfort by controlling the humidity and the temperature will help with these problems, boost productivity, and even improve the general wellbeing of the occupants.

Controlling temperature and humidity over all load conditions takes some planning when designing your HVAC system. To do this properly, we must understand the purpose and function of Modulating Hot Gas Reheat.

Modulating Hot Gas Reheat consists of a reheat coil downstream of the evaporator coil, a modulating reheat hot gas valve, a modulating condenser hot gas valve, and a reheat controller. The evaporator coil cools the mixed air below the dew point and then reheats the air with the reheat coil. The modulating valves allow only the needed amount of reheat, creating a consistent supply of air temperature. Modulating hot gas reheat is the solution to controlling high humidity loads.