W
W
W
W
WARNIN
ARNIN
ARNIN
ARNIN
ARNING
G
G
G
G
LP & N
LP & N
LP & N
LP & N
LP & NG ARE EXTREMEL
G ARE EXTREMEL
G ARE EXTREMEL
G ARE EXTREMEL
G ARE EXTREMELY FL
Y FL
Y FL
Y FL
Y FLAMMABLE SO
AMMABLE SO
AMMABLE SO
AMMABLE SO
AMMABLE SO
TTTTTAKE EXTRA PRECA
AKE EXTRA PRECA
AKE EXTRA PRECA
AKE EXTRA PRECA
AKE EXTRA PRECAUTIONS WHEN
UTIONS WHEN
UTIONS WHEN
UTIONS WHEN
UTIONS WHEN
PERF
PERF
PERF
PERF
PERFORMIN
ORMIN
ORMIN
ORMIN
ORMIN G ANY W
G ANY W
G ANY W
G ANY W
G ANY WORK T
ORK T
ORK T
ORK T
ORK TO THE HEA
O THE HEA
O THE HEA
O THE HEA
O THE HEATER
TER
TER
TER
TER
CT-02
page 1 of 1
rev 10/06
Bosch Water Heating
340 Mad River Park, Waitsfield, VT 05673
©
BBT
NORTH AMERICA CORPORATION
Bosch Group
THERMOCOUPLE AND PILOT TEST
MODELS:
1000P, 1600P,
260PN, 425PN
A. Pilot does not stay lit when the button is
released.
1. When lighting pilot, ensure the gas valve button is fully de-
pressed and held down for at least 15 seconds after pilot is
lit.
2. Pilot flame should be a sharp blue flame that fully engulfs
the thermocouple tip. If pilot does not look this way, please
see bulletin ‘CT-22 Cleaning pilot assembly’ for instructions
on how to clean pilot assembly and orifice.
3. If heater is equipped with an AQ4 power vent kit (models
1600P and 425PN only), press reset button on power vent
spill switch to check if it is tripped. NOTE: running the heater
without electrical power to power vent fan will trip the spill
switch. Also check the AQ4 safety circuit connections for
corrosion or loose connections. Consult AQ4 manual for part
locations.
4. Check the electromagnet connections. The electromagnet
is located on the back side of the gas valve. The electromag-
net connection from the thermocouple is a 5 mm brass nut
that screws into a 17 mm aluminum nut. Tighten both nuts
snugly but do not over tighten.
5. Check if connections at both temperature limiters (ECO) are
loose or corroded. Clean any corrosion with very fine sand
paper or an eraser and reconnect leads.
6. If cleaning the terminals attached to the ECO’s does not fix
the problem, choose one ECO and remove two wires at-
tached. Connect a jumper wire between the two wires re-
moved from the ECO. Try to relight the pilot. If the pilot
flame now remains on, the ECO may be defective. If the
pilot still goes out, remove jumper, reconnect wires leads
and perform the same step with the other ECO.
Note:
Never attempt to operate heater for normal
use with jumper wire connected!
7. Replace ECO.
8. Have a licensed gas technician verify the proper operation of
the thermocouple. To test the thermocouple, disconnect wire
from the thermocouple where it connects to the upper ECO
(located top right side of the heat exchanger). Insert a multi-
meter probe into the thermocouple lead and attach or hold
the other probe to the metal chassis of the heater (DC com-
mon). Light the pilot flame and hold button while observing
the meter reading. If the reading is 24mVDC or more the
thermocouple is good.
B. Pilot goes out during use
1. Light the pilot and allow it to warm the thermocouple tip for
2 minutes.
2. Perform drop test by blowing out the pilot flame and listen
for the electromagnet to close. This closure will make a dis-
tinct clunk noise as it shuts. The time between blowing out
the flame and the electromagnet closing should be between
20 and 30 seconds. Units equipped with an AQ4 power vent
kit have drop times between 10 and 15 seconds.
3. Repeat drop test several times to confirm it is consistent
4. If drop times are not within specifications, then follow steps
2-7 in section A. After each step, repeat drop test. Proceed
to the next step until drop test is within specifications.
C. Pilot goes out during use and drop test is
within specifications.
1. Check the vent size and length. Vent should be 5 inches in
diameter for the 1600P and 425PN and 4 inches in diameter
for the 1000P and 260PN. The heater must have a rise of 1-
foot before any elbows in the vent system, at least 6 feet
vertical in length and terminate through the roof. Any reduc-
tion in vent size or the presence of an elbow directly on the
top of the unit may cause the flue gas sensor to trip the pilot
safety circuit. Please see the venting section in the manual
for more detailed information regarding the required venting
for this heater.
2. Inspect the draft hood and heat exchanger fins for signs of
soot build-up or any other foreign material such as spider
webs. Clean out any debris found in the vent hood. Signs of
soot indicate insufficient combustion air or exhaust draft.
Check for vent assembly blockage or combustion air block-
age on the underside of the unit. Ensure combustion air
requirements are being met as specified in the installation
manual.
3. Measure the outgoing temperature of the hot water exiting
the unit. Temperature in excess of 160F may trip the pilot
safety circuit. The heater must not be supplied with water in
excess of 90F. Preheated water may cause the heater to
overheat the outlet water and shut down as a safety precau-
tion.
Before replacing the thermocouple, please test the
thermocouple safety circuit and the pilot as follows.