LAARS Mighty Therm AP (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 8)

LAARS Heating Systems
Page 8
Before operating the heater, the complete gas supply
system and all connections must be tested for leaks using
a soap solution. Do not use raw fl ame.
Caution
Since some leak test solutions (including soap
and water) may cause corrosion or stress
cracking, the piping must be rinsed with water
after testing, unless it has been determined
that the leak test solution is noncorrosive.
2.5 Electrical Wiring
WARNING
The heater must be electrically grounded in
accordance with the most recent edition of
the National Electrical Code, ANSI/NFPA 70.
In Canada, all electrical wiring to the heater
should be in accordance with the latest edition
of CSA C22.1 Canadian Electrical Code, Part
1. Do not rely on the gas or water piping to
ground the metal parts of the heater. Plastic
pipe or dielectric unions often isolate the
heater electrically. Service and maintenance
personnel who work on or around the heater
may be standing on wet fl oors and could be
electrocuted by an ungrounded heater.
Wiring diagrams are included in the information packet
provided with each unit.
1. All Model AP pool heating heaters need 115V
60Hz supply voltage unless specifi cally ordered
otherwise.
2. The 1825 models are supplied with 3/4 HP pump
motors. All other models are supplied with 1/2 HP
pump motors. Consult the National Electrical Code
or the Canadian Electrical Code regarding branch
circuit requirements for equipment with these
motors.
3. The heaters should be wired exactly as shown in the
wiring diagram.
IMPORTANT NOTE: The pool fi lter pump and heater
must be electrically interlocked so the heater cannot
come on unless the pump is running and there is full
fl ow in the fi lter piping where the heater is connected. If
the pool fi lter pump operation is intermittent the heater
must be shut off prior to pump shutdown. See paragraph
heading Auxiliary Time Clock Wiring on the next page.
If the backwash operation is manual the heater must be
shut off manually during backwashing.
Distance from Gas Meter
Heater or Last Stage Regulator
Size
0-100' 100-200' 200-300'
0-30.5m 30.5-61m 61-91.4m
500 1½" 2" 2"
600 1½" 2" 2½"
715 2" 2" 2½"
850 2" 2½" 2½"
1010 2" 2½" 3"
1200 2½" 3" 3"
1430 2½" 3" 3"
1670 2½" 3" 3
1825 2½" 3" 3½"
NOTE: These fi gures are for Natural Gas (.65 Sp. Gr.), and are
based on 1/2" water column pressure drop. Check supply pressure
with a manometer, and local code requirements for variations. For
Propane Gas, reduce pipe diameter one size. An average number
of tees and elbows have been taken into account.
Table 3 - Gas Piping Sizes
Figure 8 - Sediment Trap Installation
To
Equipment
Inlet
Gas Supply
Inlet
Tee
Fitting
3" (76mm) Min.
Cap
Nipple
5. Provide gas supply pressure to the heater as
follows:
Natural Gas Propane Gas
In. W.C. kPa In. W.C. kPa
Max. 10 2.5 13 3.4
Min. 6.5 1.6 11 2.7
NOTE: the heater and all other gas appliances sharing
the heater gas supply line must be fi ring at maximum
capacity to properly measure the inlet supply pressure.
Low gas pressure could be an indication of an undersized
gas meter and /or obstructed gas supply line.
6. The correct burner manifold gas pressure is
stamped on the rating plate. The regulator is preset
at the factory and normally requires no further
adjustment.
The gas manifold and control assembly is
factory tested and conforms to the safe lighting and other
performance criteria specifi ed in the latest editions of
ANSI Z21.13.CSA4.9, Low Pressure Boiler Standard.