Calibrating Pneumatic vav box with reheat

[isp tech]

Im calibrating a Vav box with a reheat valve. Im not sure if I am doing it right?

1. Find spring range on valve / damper
2. Get room temp
3. Set dial to temp on pneumatic T-stat
4. Adjust to mid point of valve spring range and damper range combined.

Am I correct? Thanks!!!

[CraziFuzzy]

Not really... most likely the spring is just low end of high end. and the damper is the opposite. at 8psi (not calling for heat or cool), the ReHeat valve should be shut, and the damper at min-flow position. As the branch line goes toward heat, the damper stays an min flow, and the valve opens up. As the branch line goes toward cool, the valve stays shut, and the damper opens towards max flow. As for calibrating it, it would depend on how it's designed - whether it has a velocity controller or not.