LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual - Manual (Page 38)

28
Service Manual - NeoTherm 500
Removing and Replacing the Gas Valve (continued)
B11
cont.
9. Now you can remove the whole assembly from
the machine. Figure B11-6 shows the complete
assembly.
10. The next step is to remove the high gas pressure
switch. Turn the red handle on the gas valve to the
Off position (handle up and down). This will give you
better access to the base of the high gas pressure
switch. Use two wrenches to remove the high gas
pressure switch.
CAUTION - Be very careful how you use
the pipe wrench to grip the body of the gas valve.
The covers on the sides of the valve are made of
sheet metal, and can be crushed easily. Be sure
the jaws of the pipe wrench grip the solid square
body of the valve.
11. Now you can separate the gas valve itself. Again,
use two wrenches to unscrew the large T-nipple from
the gas valve.
12. Figure B11-7 shows the gas valve after it has been
removed. Notice the rubber washer - be careful to
install this correctly when mounting the new valve.
13. To reassemble, reverse the procedure listed above.
Keep the following points in mind during reassembly:
• We already mentioned the rubber washer on the
gas valve.
• When re-attaching any parts which have pipe
threads and will be exposed to the gas, be sure to
use gas-resistant pipe dope or Teflon ® tape.
• When re-attaching the wires to the high gas pres-
sure valve, be careful not to reverse the connec-
tions. Connect the wire on the left (marked with
tape) to the contacts labeled “N.C.” (Normally
Closed).
14. After reassembly, check for gas leaks using a leak
detection solution (i.e. Hercules Megabubble® Leak
Detector or equivalent).
It is safe to
grip the valve
across this part
of the body.
Be careful not
to crush this
cover.
Fig. B11-6 - The gas assembly after removal
Fig. B11-7 - Gas valve
Rubber
washer