LAARS Mighty Therm AP (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 12)

LAARS Heating Systems
Page 12
and the chemical balance of the water has been adjusted
to a stable pH of 7.2 to 7.8. After the pool water is
fi ltered, and the pH is verifi ed at 7.2 to 7.8, verify that the
chlorine or bromine residual is no more than 2.0 to 4.0
ppm, the total alkalinity is 80 - 120 ppm and the calcium
hardness is between 200 - 400 ppm. Corrosion and/or
“liming” of the heat exchanger is possible when these
levels are not maintained and the heater is fi red.
1.
Before placing the heater in operation, be certain
that the heater is fi lled with water and that all air is
purged from the system. Open all the valves in the
secondary piping.
2. With the fi lter pump running, run the heater pump in
manual “CONSTANT PUMP” for minimum of 10
minutes and listen for the fl ow switch to make as the
pump is started. Loosen the pipe plug on the top of the
pump scroll casting to bleed off any air. NOTE: If the
system will be operated in a manner that causes air to
be drawn into the heater and the secondary piping, an
automatic fl oat type air vent should be permanently
installed on top of the pump scroll.
3. To check the heater fi ring, proceed as follows:
a. Turn off the power switch.
b. Turn off all manual gas valves and wait fi ve
minutes (Figure 14).
c. Set operating control to the lowest setting.
d. After placing the manual pilot gas valve in the
open position and resetting all safety devices
(high limit, low water cutoff, etc.), the pilot(s)
can be lit following the procedure on the
heater rating plate.
e. For standing pilot system, press on pilot
relay lever (see Figure 15), light pilot and
keep relay lever depressed for one minute
then release. Once the pilot is lit, turn power
switch to “AUTO PUMP.”
f. Wait 5 minutes and turn up operating
control until heater fi res (for intermittent
ignition system, the pilot will be ignited
automatically). The main burners should
ignite smoothly. Turn the operating control
back to the lowest setting.
Note: Do not operate the heater until the
following safety checks have been performed.
3.3 Safety Shutoff Component Checkout
1. Once the pilot(s) is lit and has been established for
fi ve minutes, the fl ame failure response time should
be checked as follows:
Systems 4, 9, and 11 - (intermittent ignition). With this
system pilots are automatically lit when the operating
controls call for heat. If the pilot fl ame fails for any
reason, the main valve is shut off within one second and
the pilot spark ignition is initiated until the pilot fl ame
has been reestablished. This sequence should be checked
by turning off the manual pilot gas valve (see Figure 14),
and, at the same time, monitoring the audible sparking at
the pilot burner and signal interruption to the main valve.
Caution
Propane gas is heavier than air and sinks to
the ground. Exercise extreme care in lighting
the heater when so equipped.
System 16 - (electronically supervised standing pilot
system). Extinguish the pilot fl ame by placing the manual
pilot valve in the closed positions (see Figure 14), and at
the same time, begin recording the time it takes for the
output signal from the electronic ignition control to be
interrupted. The signal interruption can be detected either
with a test light or a voltmeter. The response time should
never exceed one second.
Figure 15 - Pilot Safety Relay.
Pilot Relay Manual
Reset Switch
(Standing Pilot Systems)
Figure 14 - Manual Gas Valves.
Pilot Valve
Main Gas Valve
Pilot Valve
Main Gas Valve
ON POSITION
OFF POSITION