Trane VAV-SVX02B-EN manual Model 3501-Pneumatic Volume Regulator

Model 3501—Pneumatic Volume Regulator

Model 3501

The model 3501 PneumaticVolume Regulator (PVR) is capable of operating with normally-open or normally-closed air valves and can operate with either direct-acting (DA) or reverse-acting (RA) thermostats.

Installation

1.Attach bracket either vertically or horizontally to the installation surface. Horizontal is preferred, vertical is acceptable, any other position is not acceptable.

2.Insert controller into its bracket. Controller may be face up, face down, face left, or face right.The controller LO and HI stat delta P must be calibrated in the same position that it is installed.

Selecting Direct- or Reverse-Acting Thermostat (3501)

The model 3501 PVR must be calibrated to operate with either a direct-acting or reverse-acting thermostat.The control must also be changed when used with a normally-open or normally-closed air valve.

Use the following procedure to set-up the PVR:

1.Select damper action (NO or NC). Loosen damper selection switch screw and align to either the NO or NC pointer with damper pointer and tighten screw.

2.Now determine the type of thermostat that will be used. If a direct-acting thermostat is used, the reset start pressure is typically 8 psi. If a reverse- acting thermostat is used, the reset start pressure is typically 3 psi.

3.With an accurate gage (0–30 psi) connected to port “G”, regulate the thermostat pressure to port “T” to 10.5 psi.

4.Adjust reset start to indicate 2.5 psi on port “G”

Adjusting the Reset Span (3501)

The reset span is factory-set at 5 psi. This is the thermostat pressure differ- ence from which the PVR delivers flow from minimum to maximum setpoints.This range is not normally changed unless a special control scheme is used where control operation must be changed.

To field adjust a different reset span, follow these steps:

1.Connect an accurate gage to port “G”.

2.Apply 20 psi to port “T”.

3.Adjust reset span to indicate the desired span on port “G”.

4.LO-stat and HI-stat delta P must now be readjusted (see following calibration procedure).

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