Bosch Appliances GWH 1600 H Ventilation Hood User Manual


 
10 AQ4 Manual
Troubleshooting
5 Troubleshooting
5.1 Introduction
Many of the questions customers ask regarding
operation of this unit can be answered by following
the troubleshooting steps outlined below. Visit our
website at www.boschhotwater.com for more
detailed troubleshooting. For best results, perform
each step before proceeding to the next.
5.2 Power vent motor runs all the time
or intermittenly without water flow
1. The AQ4 power vent fan motor is equipped with a
45 second post purge cycle. The fan motor should
continue to run for this length of time after the
hot water flow has been shut off.
2. The power vent motor is flow switch activated. If
the internal paddle inside the flow switch is
jammed, it may constantly send a signal to turn
on the fan. Shut off water supply to heater and
drain. Remove flow switch from water heater
piping by removing clips on both ends. Flush
water through both ends of flow switch to free
up internal paddle and clear debris. After flushing,
shake flow switch up and down. The internal
paddle should be heard moving freely back and
forth.
3. Large amounts of water demand can create
pressure drops throughout plumbing. This may
allow for movement of the power vent flow switch
and activate the fan. Activated sprinkler systems
or flushed toilets are common causes for this
symptom. Consult a plumbing professional for the
use of check valves to prevent unintentional water
flow through the heater.
4. In buildings with excessively high water pressure,
a condition known as “water hammer” may exist.
This condition is caused by a combination of high
water pressure and the abrupt closing of a faucet
valve or internal washer/toilet valve. This instant
change in flow results in an instant change in the
internal pressures in the pipe, which then sends
a shock wave through the pipe. This physical
shock will shake, rattle or cause a loud bang in
the plumbing which we refer to as “water
hammer.” Such a shock wave may cause movement
of the power vent flow switch which will activate
the fan. Consult a plumbing professional for the
use of a pressure reducing valve, expansion tank
or water hammer arrestor to combat this
condition.
5.3 Pilot will 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 dirty. Consult water heater
installation manual for instructions on cleaning
the pilot assembly.
5.4 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, then 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.
5.5 Noise when power vent motor is
running
1. Ensure power vent motor is mounted level with
motor shaft horizontal or premature motor bearing
wear may occur.
2. Ensure power vent motor is mounted using the
supplied vibration mounts or premature motor
bearing wear may occur.
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.