Building Pressure Control — a
modulating spring return actuator is used to control the return air amounts. The return air damper modulates from fully open to fully closed based on a signal from a remote pressure sensing device.
Turn both knobs to the upper most pressure setting. You may have to remove the outdoor pressure tap tubing. The return air damper should close.
BLOWER
EXHAUST (OPTIONAL)
SUPPLY
|
| MAIN VALVES |
HEAT |
| |
|
| DIRTY FILTERS |
75 | 70 |
|
80 | 65 | (OPTIONAL) |
85 | 60 | |
90 | 55 |
|
PHOTOHELIC
GREENHECK
With Maxitrol 44 Room Thermostat
Building
Pressure Control
Set both knobs at the lowest setting and the damper should open. It may take one to two minutes for the damper to reach the desired position.
Reset the correct pressure limits before starting the unit.
80
85
65
60
This picture shows a typical photohelic setting. Typical settings are 0.0 inch wc for the lower and 0.10 inch wc for the upper pressure setting. The needle in this photo indicates a negative building pressure. During correct operation, the indicating needle will remain between or near the setting needles.
Pressure Indicating | Pressure Setting |
Needle | Needles |
Pressure Setting Knobs
Photohelic Gauge
90
55
External Signal — a modulating spring return actuator is used to control the return air amounts. Return air damper modulates from fully open to fully closed based on an external
The return air damper will close with a 10 VDC or
20 mA signal. The return air damper should open with a 2 VDC or 4mA signal. The damper actuator may take a few minutes to open or close.
EXHAUST
(OPTIONAL)
SUPPLY
HEAT
75 70
80
65
Model MSX