LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual - Manual (Page 36)

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Service Manual - NeoTherm 500
Removing and Replacing the Gas Valve
The modulating gas valve consists of a valve body that controls the on/off
gas flow and a negative pressure regulator. It provides the air/gas ratio
control in combination with the Venturi to the unit.
The easiest way to remove the gas valve is to remove a section of the
gas input piping, including the gas valve and the high gas pressure
switch. Once you have done this, you can separate the gas valve from
the rest of the assembly. Figure B11-1 shows how the parts are arranged.
Fig. B11-1 - Gas shutoff valve (typical)
B11
Tools and equipment required:
• Small Phillips-head screwdriver (#1)
• 3/8” and 5/16” sockets
• 4 mm Allen wrench
• Two medium-sized pipe wrenches
• Gas-resistant pipe dope or Teflon® tape
• Gas leak detection solution (“bubble spray”)
• Container for removed parts
Procedure:
1. Turn off power to the machine. Use the main discon-
nect switch on the front of the machine, just above
the control panel.
2. Remove the front and right side panels.
3. Shut off the gas at the gas shutoff valve on the right
side of the machine (yellow handle). See Fig. B11-1.
4. Unplug the wires running to the gas valve. (The
connector is keyed, and can only be plugged in one
way.) See Fig. B11-2.
Fig. B11-2 - Wiring connector for gas valve (typical)