Pentair MiniMax NT Standard Series - Manual (Page 19)

Rev. A 1-2-02 P/N 472032
19
SAFETY CONTROLS
AIR PRESSURE (FAN) SWITCH
The air pressure switch is a safety device used to insure that the blower (fan) is operating and has been designed
to monitor the vacuum (negative) pressure within the blower housing. The air pressures switch is factory set
and is in the ignition module circuit—the ignition module does not operate unless the air pressure switch and
all safety switches are closed.
Basic Operation
AIR PRESSURE SWITCH
Adjustment Knob
Typical Water Pressure Switch
Figure 18.
Figure 19.
WATER PRESSURE SWITCH
The water pressure safety switch closes when there is a sufficient flow of water to the heat exchanger to safely
operate the heater. The switch operation must be verified during initial operation of the heater after installation—
the switch is set at 1 PSIG and the switch contacts must not be closed in the absence of water flow. NOTE: See,
Below Pool Level Installation instructions on page 11. The switch may remain closed with no water flow if
there is more than a 3 feet elevation difference between the heater (heat exchanger) and the pool water line—
if this is the case, the water pressure switch must be reset to maintain open switch contacts with no water flow.
NOTE
If the pool is more than one floor above or one floor below the heater, the pressure switch may have to be
replaced with a flow switch.