Takagi T-H3J-DV Service Handbook page 22

for the correct volume of gas.
Refer to the installation manual or
the current edition of the National
Fuel Gas Code, ANSI Z223.1/
NFPA 54 (U.S.) or Natural Gas and
Propane Code, B149.1 (Canada).
5. Check for obstructions in the vent
or intake air lines. Clear them if any
are found.
6. Verify that the terminations meet
the minimum clearances that
are outlined in the installation
manual and local codes. (Doing so
will minimize the risk of flue gas
recirculation.) Also, ensure that no
other appliance's exhaust gasses
can be pulled into the intake.
7. Check for signs of contaminated air
inside the water heater's cabinet
and inside the fan on the fan
blades. Clean the fan and cabinet
if any debris is present. It may also
be necessary to inspect for debris
or a partial blockage of the burners
that could affect the flame quality.
Also, check for any partial air
obstructions in the exhaust venting
or finned air passage through the
heat exchanger. If the fan is unable
to push sufficient air, then the
burners will become gas rich and
trigger the 101 or 991 code.
◦
To check and clean the
fan, see "Cleaning the
Combustion Components,"
page 39.
◦
To check and clean the
burner, refer to "Cleaning the
Combustion Components,"
page 39.
NOTE: Do not proceed to the
next step until this one has
been completed and these
causes have been ruled out.
Improperly installed venting,
incorrect dip switch settings,
22 • On-Demand Water Heater Service Handbook for 240, 340 & 540 Condensing Models
and obstructions in the
venting or heater will affect
manifold pressure readings.
8. Contact Technical Support
regarding the manifold pressure.
(See "," page 34.) With approval
from Technical Support, adjust the
manifold pressure to the correct
values, if necessary.
9. Complete the following procedure
to clear the 101/991 error code:
9.1 Make sure that the water
heater is powered on.
9.2 Press the on/off button on
the remote/temperature
controller so the amber
standby light is off.
9.3 On the computer board,
simultaneously press and
hold the INCREASE and
DECREASE buttons for five
seconds. (See Figure 7 or
Figure 8, as appropriate.)
9.4 Release the buttons when
the green LED on the
computer board turns off.
(Figure 7 or Figure 8.)
The green LED will then turn
back on.
9.5 Shut off power to the heater
using the on/off switch
above the computer board.
9.6 After 5 seconds, turn the
power on. The heater will
be in standby and ready for
operation.