Bosch AQ4 GWH 1600 P - Manual (Page 11)

11 AQ4 Manual
Troubleshooting
5.3 Pilot will not stay lit when manually
lit (1600P and 425PN) or will not
spark automatically with hot water
flow (1600H and 425HN)
1. Check the linear safety spillage switch reset
button to see if it is tripped (See Section 2.6).
Overheating or loss of power to the unit will trip
the safety spillage switch and stop the flow of
gas.
2. Check the entire pilot safety circuit (including
the safety spillage switch) for loose or dirty
connections (See Fig 8). Clean any corrosion
evident with a pencil eraser or light sandpaper.
3. Pilot flame is weak or yellow. Consult water
heater installation manual for instructions on
cleaning the pilot assembly.
5.4 Spark but pilot will not light (1600H
and 425HN only)
1. Check time delay relay for proper setting. See
Section 3.1.1. Set time delay relay adjuster to the
(2) second position for 1600H and 425HN only. If
the pilot will not consistently light, move adjuster
to the (3) second position and to (4) second
position if needed. DO NOT exceed position (4).
Complete saftey interlock test after changing
setting. See Section 3.1.3.
5.5 Pilot and/or burners go out during
hot water use
1. Inspect entire vent system for blockage or
obstruction. Ensure the back draft flapper
installed on the power vent hood swings freely.
2. Verify power vent fan operates with water flow.
If not, verify wire connection from flow switch to
fan motor. Clean cold water inlet filter and verify
flow rate through the water heater is adequate
enough to activate the flow switch. If flow rate
is more than 0.5 GPM, the flow switch may be
defective and should be replaced.
3. If heater is newly installed, verify power vent fan
motor is not installed backwards (See Fig 4).
4. Ensure power vent motor is mounted as close as
possible to the VH1-4 vent hood. Mounting the
power vent motor directly on top of or close to
the water heater, may result in lifting flames and
pilot outages. Vent pipe length must be at least
2 feet.
5.6 Noise when power vent motor is
running
1. Ensure power vent motor is mounted level with
motor shaft horizontal to prevent premature
motor bearing wear.
2. Ensure power vent motor is mounted using the
supplied vibration mounts to prevent premature
motor bearing wear.
3. Remove vent pipe connection from water heater
to power vent motor. Inspect internal fan wheel
for broken fins. If any damage is evident, order
online or call Technical Support (800) 642-3111
for a replacement wheel kit.