Page 15
Legacy
™
Model LRZM Pool/Spa Heater Installation and Operation Manual
7.
If the gas supply pressure is less than required,
check for undersized pipe between the meter and
the heater, a restrictive
fi
tting, or an undersized
gas meter. Gas supply pressures to the heater are
listed in Table 5.
NOTE
The maximum inlet gas pressure must not
exceed the speci
fi
ed value. The minimum
value listed is for the purpose of input
adjustment. Refer to Table 5.
8.
Before operating the heater, test the complete gas
supply system and all connections for leaks using
a soap solution. Do not use an open
fl
ame.
CAUTION
Some leak test solutions (including soap and water)
may cause corrosion or stress cracking. Rinse the
piping with water after testing.
ATTENTION
Certaines solutions d’essai d’étanchéité (y compris
l’eau et le savon) peuvent causer de la corrosion
ou de la
fi
ssuration. Rincez les tuyaux à l’eau après
l’essai d’étanchéité.
4.2 Manifold
Pressure
Con
fi
rm that gas supply pressure is correct. If
the gas supply pressure is less than required, check
for undersized pipe between the meter and the heater,
a restrictive
fi
tting, or an undersized gas meter. Gas
supply pressures to the heater, when it is operating, are
listed in Table 5.
CAUTION
Manifold gas pressure for the Legacy natural gas
heaters should be set at
4.0"
WC. Propane heaters
should be set to 9" WC.
ATTENTION
La pression du collecteur de pression pour les
systèmes de chauffage au gaz naturel devrait être
de 4.0'’ WC. Pour les sytèmes de chauffage au gaz
propane devrait être de 9'’ WC.
The manifold pressure may be checked by
connecting a manometer to the pressure port on the
outlet side of the valve. You will need to remove the
1/8" NPT protective plug form the port and install the
appropriate 1/8" NPT
fi
tting to connect your manom-
eter. The pressure will be zero when the heater is not
running. When the heater is operating the manifold gas
pressure should be 4.0" WC for natural gas heaters and
9.0" WC for LP gas heaters.
Before adjusting the manifold gas pressure check
the supply side pressure. Make certain the entire
supply side gas train (gas line, shutoffs, meter, etc.)is
correct for the heater size. To adjust the manifold gas
pressure,
fi
rst remove the slotted cap on the top of the
gas valve to the right of the control knob. Under the
Table 4. Supply Gas Pipe Size Requirements*
Distance from Gas Meter
Heater
Size
0-50 feet
(0-15 m)
50-100 feet
(15-30 m)
100-200 feet
(30-60 m)
in.
mm
in.
mm
in.
mm
125
3/4
19
1
25
1
25
175
1
25
1
25
1-1/4
32
250
1
25
1-1/4
32
1-1/4
32
300
1-1/4
32
1-1/4
32
1-1/2
38
400
1-1/4
32
1-1/2
38
1-1/2
38
Notes:
*1. These numbers are for natural gas (0.65 Sp. Gr.) and
are based on 1/2 inch (3.45 kPa) water column pressure
drop. Check supply pressure with a manometer, and lo-
cal code requirements for variations.
For LP gas, reduce
pipe diameter by one size, but maintain a minimum
3/4" diameter.
2. Check supply pressure and local code requirements before
proceeding with work.
3. Pipe
fi
ttings must be considered when determining gas
pipe sizing.
Table 5. Gas Supply Pressure Requirements
Figure 6. Proper Design for a Sediment Trap/Drip Leg
APPROVED
6.
Disconnect the heater and its individual shutoff
valve from the gas supply system during pressure
testing of the system at pressures higher than 1/2
pounds per square inch (psi) (3.45 kilopascals
[kPa]). If the test pressure is equal to or less than
1/2 psi (3.45 kPa), close the manual shutoff valve
on the heater during the piping pressure test.
Supply Pressure
Minimum
Maximum
Natural Gas
5.5 inches W.C.
(1.4 kPa)
10.0 inches W.C.
(2.5 kPa)
LP Gas
10.0 inches W.C.
(2.5kPa)
14.0 inches W.C.
(3.5 kPa)
Manifold Pressure
Nominal
Natural Gas
4.0 inches W.C. (1.0 kPa)
LP Gas
9.0 inches W.C. (2.2 kPa)
Summary of Contents for Legacy LRZM
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