Gas Pressure; Gas Valve Replacement - Lochinvar Shield SNR150-100 Installation & Service Manual

6
Gas connections
17. Check burner performance by cycling the system while
you observe burner response. The burner should ignite
promptly. Flame pattern should be stable. Turn system
off and allow burner to cool, then cycle burner again to
ensure proper ignition and flame characteristics.
Figure 6-4 Inlet Gas Supply Check - Models SNR150/100
-- SNA285-125
LOOSEN THE SET SCREW ONE (1) FULL TURN AND
PLACE THE MANOMETER TUBING OVER THE
PRESSURE TAP
Figure 6-5 Inlet Gas Supply Check - Model SNA400/125
LOOSEN THE SET SCREW ONE (1) FULL TURN AND
PLACE THE MANOMETER TUBING OVER THE
PRESSURE TAP
Figure 6-6 Inlet Gas Supply Check - Model SNA500/125
LOOSEN THE SET SCREW ONE (1) FULL TURN AND
PLACE THE MANOMETER TUBING OVER THE
PRESSURE TAP
42

Gas pressure

The gas pressure must remain between 4 inches w.c. (natural),
8 inches w.c. (LP) minimum and 14 inches w.c. (natural and
LP) maximum during stand-by (static) mode and while in
operating (dynamic) mode. If an in-line regulator is used, it
must be a minimum of 10 feet from the Shield water heater.
It is very important that the gas line is properly purged by the
gas supplier or utility company. Failure to properly purge the
lines or improper line sizing, will result in ignition failure.
The problem is especially noticeable in NEW LP installations
and also in empty tank situations. This can also occur when
a utility company shuts off service to an area to provide
maintenance to their lines.

Gas valve replacement

The gas valve MUST NOT be replaced with a conventional
gas valve under any circumstances. As an additional safety
feature, this gas valve has a flanged connection to the venturi
and blower.
DETAIL
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Installation & Service Manual
TM
Failure to follow all precautions could
WARNING
result in fire, explosion, or death!
DO NOT adjust or attempt to measure
WARNING
gas valve outlet pressure. The gas valve is
factory-set for the correct outlet pressure.
This setting is suitable for natural gas
and propane (when configured for LP),
requiring no field adjustment. Attempting
to alter or measure the gas valve outlet
pressure could result in damage to the
valve, causing potential severe personal
injury, death, or substantial property
damage.