MasterTemp Pool and Spa Heater P/N 474131 Rev. M 8/2020
42
SAFETY CONTROLS
AIR FLOW SWITCH (AFS)
The air flow switch, see Figure 40, is a safety device 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 flow
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
WARNING
Hazardous pressure. Do not bypass the Water
Pressure Switch or render it inoperable.
The water pressure switch, (see Figure 42). If the water flow is restricted, the
water pressure switch may prevent the burner from firing and cause the “Service
System” light to go on. If the light remains on after the filter has been serviced,
have a qualified service technician check the system.
For deck-level heater installations, the Water Pressure Switch is factory set
at 20.6 kPa (3.00 psi).
NOTE:
See, “Below Pool Level Installation” on page
13
. If the pressure switch is .3M (1 ft.) below or above the pool water level,
reset the switch so that it is open when the pump is off and closed when the
pump is running. Turn the star-wheel on the switch clockwise ( ) to
raise setting (heater below the pool) and counterclockwise ( ) to lower
the setting (heater above the pool – see Figure 42. Test the switch after
resetting.
NOTICE:
When the heater is mounted more than 1.5M (5 ft.) above or 1.2M
(4 ft.) below the deck level, a Pressure Switch is no longer adequate. A Flow
Switch must be installed instead.
NOTICE:
Heater operation with incorrect
Pressure Switch setting may cause operation
with no water flow. Operation of the heater
without sufficient water flow may severely
damage it and
will void the warranty
.
HIGH LIMITS
A “High Limit”, is a safety device that opens
the electrical circuit and shuts off the heater
based on a water temperature set point within
the “High Limit Device”. The MasterTemp
series of heaters contains two (2) high limit
devices which are located on the main inlet
/ outlet header.
Figure 41.
Water
Pressure
Switch
Star Wheel
A reference scale is on
the back of pressure switch
Turn star wheel
clockwise
to
raise
pressure set point if pressure switch is more
than 1.2 M (4 ft) below water level
Turn star wheel
counterclockwise
to lower
pressure set point if pressure switch is more
than 1.5 M (5 ft) above water level
1.2 M (4 ft)
1.5 M (5 ft)
Figure 42.
Air Flow Switch
Figure 40.
Section 2. Operations
