Manifold Pressure - Jandy LG125 Installation And Operation Manual

Model LG Pool and Spa Heater
Table 4. Natural Gas Pipe Size Requirements*
Distance from Gas Meter
0-50 feet
Heater (0-15 m)
Size in. (mm) in.
125 3/4 (19)
175 1 (25)
250 1 (25) 1-1/4
325 1-1/4 (32) 1-1/4
400 1-1/4 (32) 1-1/2
Notes:
*1. These numbers are for natural gas (0.65 Sp. Gr.) and are
based on 1/2 inch (13mm) water column pressure drop.
Check supply pressure with a manometer, and local code
requirements for variations. For liquefied petroleum gas,
reduce pipe diameter one size, but maintain a3/4inch (19mm)
minimum diameter.
2.Check supply pressure and local code requirements before
proceeding with work.
3.Pipe fittings must be considered when determining gas pipe
sizing.
Figure 6. The proper design for a sediment trap/drip leg.
4. Install a sediment trap (drip leg) ahead of the gas
controls (see Figure 6). Fit the trap with a
threaded cap which can be removed for cleaning.
5. Install a manual gas shutoff valve for service and
safety. Do not use a restrictive gas cock. DO
NOT USE FLEXIBLE GAS PIPING, it will
restrict the gas flow to the heater.
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.
7. If the gas supply pressure is less than required,
check for undersized pipe between the meter and
the heater, a restrictive fitting, or an undersized
gas meter. Gas supply pressures to the heater
are listed in Table 5.
50-100 feet 100-200 feet
(15-30 m) (30-60 m)
(mm) in. (mm)
1 (25) 1 (25)
1 (25) 1-1/4 (32)
(32) 1-1/4 (32)
(32) 1-1/2 (38)
(38) 1-1/2 (38)
NOTE: The maximum inlet gas pressure must
not exceed the specified value. The minimum
value listed is for the purpose of input
adjustment. Refer to Table 5.
Table 5. Gas Supply Pressure Requirements
Supply Pressure Minimum
Natural Gas 5.5 Inches WC
(1.4 kPa)
LP Gas 10.0 Inches WC
(2.5 kPa)

Manifold Pressure

Nominal
Natural Gas 4.0 Inches WC (1.0 kPa)
LP Gas 9.0 Inches WC (2.2 kPa)
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 flame.
CAUTION
Some leak test solutions (including soap and
water) may cause corrosion or stress cracking.
Rinse the piping with water after testing.
4.2 Manifold Pressure
Confirm 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 fitting, 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 Lite2 Lg natural
gas heaters should be set at 4" WC. Propane
heaters should be set to 9" WC.
The manifold pressure may be checked by con-
necting a manometer to the pressure port on the outlet
side of the valve. You will need to remove the 1/8"
Page 11
Maximum
10.0 Inches WC
(2.5 kPa)
14.0 Inches WC
(3.5 kPa)