In the context of reheat coils in HVAC systems, what is the correct position for valves to fail?

In HVAC systems, specifically concerning reheat coils, the correct position for valves to fail is in the closed position. Failing in this manner is important for safety and system efficiency. When a valve fails closed, it prevents hot water or steam from entering the reheat coil, which can help maintain control of the indoor environment temperature and prevent overheating in critical applications.

Failing closed helps to avoid scenarios where excess heat could be introduced into a space, which could lead to discomfort or damage to sensitive equipment. Furthermore, this position minimizes the risk of water hammer or other hydraulic issues that might occur if the valve were to fail open.

Other positions, such as open or variable, can lead to uncontrolled heating and potential hazards, making the closed position the most favorable design choice for reheat coil valves in HVAC systems.