Troubleshooting; Check Control Module Fuses; Before Troubleshooting - Lochinvar Shield SNR150-100 Installation & Service Manual

12

Troubleshooting

Label all wires prior to disconnection
WARNING
when servicing controls. Wiring errors
can cause improper and dangerous
operation.
to the water heater before servicing.
Failure to comply could result in severe
personal injury, death, or substantial
property damage.
Never jumper (bypass) any device except
WARNING
for momentary testing as outlined in the
Troubleshooting chart. Severe personal
injury, death, or substantial property
damage can result.

Before troubleshooting:

1. Have the following items:
a. Voltmeter that can check 120 VAC, 24 VAC, and
12 VDC.
b. Continuity checker.
c. Contact thermometer.
2. Check for 120 VAC (minimum 102 VAC to maximum
132 VAC) to water heater.
3. Make sure the tank is calling for heat.
4. Make sure all external limit controls are installed and
operating.
Check the following:
1. Wire connectors to control module and connection
board are securely plugged in.
2. Gas pressures:
• Maximum: 14 inches w.c. (natural and LP) with no
flow (lockup) or with water heater on
• Minimum: 4 inches w.c. (natural), 8 inches w.c. (LP)
with gas flowing (verify during water heater startup)
62
Always disconnect power
Installation & Service Manual
TM

Check control module fuses

ALWAYS check control module fuses
NOTICE
before replacing control module or any
major components (blower, etc.). If one
of these fuses is blown, it can prevent the
control module or other components from
operating.
1. Turn OFF power to the water heater at the external
disconnect switch.
2. Remove top access cover.
3. Remove the control module cover.
4. Inspect fuses F2, F3, F4, and F5, see FIG. 12-1 below.
Figure 12-1 Control Module Fuses
F4 - 3.15 AMP FUSE
BLOWER
F5 - 5 AMP FUSE
PUMPS
F2 - 3.15 AMP FUSE
24V SUPPLY
5. The water heater is shipped with three (3) spare fuses in a
plastic bag attached to the control module cover.
6. If necessary, replace open fuse (F3 is 1.25 amps, F2 and F4
are 3.15 amps, and F5 is 5 amps).
Note: Fuses F2 - F5 are all slow blow fuses.
Do not jumper fuse or replace with any fuse
WARNING
except as specified. Failure to comply could
result in severe personal injury, death, or
substantial property damage.
7. Install control module cover and top access cover after fuse
inspection.
8. Restore power to the water heater at the external
disconnect switch and verify water heater operation
(Section 9 - Start-up) after completing water heater service.
F3 - 1.25 AMP FUSE
MAIN BOARD