Troubleshooting; Introduction 1; Pilot Will Not Light 1; Pilot Will Light But Not Stay On When Button Released 1 - Bosch AQ 125BO LP Use And Care Manual

Troubleshooting
6 Troubleshooting
6.1 Introduction
Many of the questions customers ask regarding
operation of this unit can be answered by following the
troubleshooting steps as outlined below. Visit our web
site at www.boschhotwater.com for more detailed
troubleshooting. For best results, perform each step
before proceeding to the next. The suggested solutions
may require that the cover be taken off. (See chapter
3.4).
6,2 Pilot will not light
1. If the unit was just installed or the gas lines have
been worked on, there may be air in the gas line. To
bleed air out of the gas line, hold down the gas valve
button while hitting the piezo ignitor button '_-, every
second.
• 2. Check to make sure the manual gas shut off valve
is in the open position. Have licensed gas technician
or service person check the presence of gas at the
gas pressure measuring tap on the left side of the
gas control valve. If gas is not present, the regulator
may be locked up and need replacing. See
chapter 3.5 for required gas pressures.
• 3. Clean or replace the pilot orifice. See chapter 5.3
for instructions.
6,3 Pilot will light but not stay on when
button released
• 1. When lighting pilot ensure the gas valve button is
fully depressed and held down for at least 15 sec
after pilot is lit.
• 2. Pilot flame should be blue in color and hitting the
thermocouple tip. See chapter 5.3 for instructions.
• 3. Check the electromagnet connections. Electroma-
gnet is located on the right side of the gas valve
behind the piezo push-button assembly. The
Electromagnet connection is a large aluminum 17mm
hex head nut. The thermocouple end is a 5 mm brass
nut which screws into the 17 mm nut. Tighten both
nuts snugly but do not over tighten.
• 4. Check if connections at the ECO are loose or
corroded. Clean any corrosion with very fine sand
paper or an eraser and reconnect leads.
• 5. If cleaning the terminals attached to the ECO did
not fix the problem, connect a jumper wire between
the two wires attached to the ECO and try to relight
the pilot. If the pilot flame now remains on, the ECO
may be defective and need to be replaced. Do not
leave jumper connected.
• 6. Have a licensed gas technician verify the proper
operation of the thermocouple by measuring the
millivoltage from the thermocouple lead to ground.
The expected reading is 24mVDC or greater.
6.4 Burners do not ignite with water
flow
• 1. Verify the pilot is lit.
• 2. Turn temperature adjustment knob all the way
clockwise. Turn hot water faucet to full on position
and fill a quart container. If the container fills in 30
seconds or less your flow rate (1/2 gallon per minute)
is sufficient to activate the heater. If the knob is full
counter clockwise, the container will need to fill in 14
seconds (1.1 gallons per minute) to activate the
heater. Check for restrictions in the water line such
as clogged aerators or a clogged inlet water filter
screen if flow rate is not sufficient.
• 3. Clean water inlet filter screen. See chapter 5.2.
• 4. Shut off installer supplied cold water supply valve
(if none installed, install before proceeding). Open all
hot water taps supplied by the 125 BO. Wait 5
minutes and check all taps. Water running is a sign
of a plumbing cross-over. Consult a local plumber or
service person for help in correcting plumbing cross-
over.
• 5. Verify the cold water supply is connected to the
right side of the heater.
• 6. Service the water valve. See chapter 5.2 for
intervals and instructions.
6.5 Hot water temp fluctuates from hot
to cold
• 1. Shut off installer supplied cold water supply valve
(if none installed, install before proceeding). Open all
hot water taps supplied by the 125 BO. Wait 5
minutes and check all taps. Water running is a sign
of a plumbing cross-over. Consult a local plumber or
service person for help in correcting plumbing cross-
over.
• 2. Check for restrictions in the water line such as
clogged aerators, clogged shower head or a clogged
inlet water filter screen.
3. If hot water is so hot that a large amount of cold
water must be introduced to lower temperature to
comfortable level, lower output temperature. See
chapter 4.4 for instructions.
4. Check the inlet water pressure. For installation on
a private well system with the use of a pressure tank,
the lowest pressure range setting recommended is
30-50 psi (2.07 - 3.45 bar). Confirm that the
pressure tank is not water logged.
8716473147
17