Safety Controls - Pentair MiniMax NT LN Operation & Installation Manual

Section IV. Operation

SAFETY CONTROLS

VACUUM AIR PRESSURE (FAN) SWITCH
The air pressure switch, (see
used to insure that the combustion air 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 connected upstream
of the ignition module. The ignition module does not
operate unless the air pressure switch and all safety switches
are closed.
WATER PRESSURE SWITCH
The water pressure switch, (see
there is a sufficient flow of water to the heat exchanger to
safely operate the heater. The switch has been preset by
the Factory at 1½ PSI for operation. NOTE: See, Below
Pool Level Installation instructions on
may remain closed with no water flow if there is more
than a 3 ft. elevation difference between the heater (heat
exchanger) and the pool water line—if this is the case, the
water pressure switch must be reset by a qualified service
technician to maintain open switch contacts with no water
flow.
THERMAL FUSE
This is a single-use switch, mounted on combustion
chamber jacket divider (inner front panel). The fuse, (see
Figure 22), is activated by excessive temperature due to
abnormal operating conditions. Upon detection of
excessive heat within the inner front panel, the fuse will
open the safety circuit causing shutdown of the heater.
LOW GAS PRESSURE SWITCH
The MiniMax NT LN model heater uses a low gas supply
pressure switch, (see Figure
prevent operation of the heater when the gas supply
pressure is below the minimum required for proper
operation of the burners. The switch is factory set. In the
event that the switch does not close and prevents the firing
of the heater, the cause of the low gas supply pressure must
be corrected. Typical causes are undersized supply piping,
undersized gas meter or low gas regulator setting (gas
supply regulator and gas meter problems are typically
corrected by your local gas company).
Figure 20), is a safety device
Figure 21), closes when
page 8. The switch
NOTE
23), ahead of the gas valve, to
AIR PRESSURE SWITCH
Air Pressure Switch
Adjustment Knob
Typical Water Pressure Switch
Thermal Fuse
Low Gas Pressure Switch
22
Figure 20.
Figure 21.
Figure 22.
Figure 23.