Takagi T-KD20 Installation Manual And Owner's Manual - page 16
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Common Trouble Shooting
The T-KD20 can burn gas at a maximum input
rate of 185,000 BTUH. This puts a limit on the
possible output temperature and flow
capabilities. If the water doesn’t seem hot
enough, compare the flow and temperature
that is being attained to the T-KD20 flow vs.
temperature chart (See flow chart on the last
page of this manual). If the unit is not
performing according to the chart, first check
that the gas supply pipe is sized properly and
that the gas pressure is within the required
range. If the gas line is sized properly, check
the plumbing for mixing valves, thermostatic
valves, anti-scald devices, single handled
faucets with built in temperature or pressure
compensators valves and hot and cold crossed
connections. If the unit is performing in
accordance with the flow chart, it may be
undersized for the application. If the unit is
performing according to the chart, the output
temperature can be adjusted using the TK-
RE02 or the dipswitches on the unit.
It Takes Too Long to Get Hot Water
The T-KD20 takes three seconds to ignite and
three more seconds to heat the incoming
ground water up to the set temperature. The
time it takes to deliver hot water from the T-
KD20 to your fixtures depends on the length of
piping between the two. The longer the
distance, the more time it will take. If you
would like to receive hot water to your fixtures
quicker, you may want to consider a hot water
recirculation system.
The T-KD20 Will Not Initiate
First check the flow rate through the unit. If the
flow is less than .75 GPM, the unit will not
initiate. Check the filter for any debris or
damage. If you have installed a combination
system (a T-KD20 doing both domestic hot
water and space heating), completely isolate
the heating system temporarily to ensure flow
is not backfeeding through your heating
system to supply the domestic water (by-
passing the T-KD20).
If neither of those remedies start the unit, press
the lower green button marked “test (off)” on
the GFCI inside the unit. If the red light above it
does not come on, there is a problem with the
electrical supply to the unit. If that red light
does come on, hit the “reset (on)” button and
open a hot water faucet to re-try the unit. If the
problem persists contact Takagi for instructions
ERROR CODES
All Takagi units are self diagnostic for safety
and convenience when trouble shooting. If
there is a problem with the installation or the
unit, it will display a numerical error code on
the TK-RE02 (if installed) or at the bottom left
corner of the computer board to communicate
the source of the problem. Consult the
following chart for the cause of an error code:
The T-KD20 consists of five major control
operations: Temperature control, Gas control,
Water control, Burner Control, and Main
computer control
.
Computer Board
TK-RE02 Check
Point
11 Igniter
12 Flame
Detector
51
Main Gas Valve
Burning (red) LED: Blinking
Power (green) LED: OFF
72
Pre Post Check
03
Wrong Gas, Dip Switch
14 Hi-Limit
Switch
70 Computer
Board
Burning (red) LED: OFF
Power (green) LED: Blinking
71 Proportional
Valve
61 Fan
Motor
Burning LED and Power LED:
Blinking Alternately
21 Vent
Pipe
31 Thermistor
Burning LED and Power LED:
Blink Simultaneously
65
Water Control Valve