T-K3 Service Manual
Ver. 1.05
24
CONFI DENTIAL
10-12. Hi-limit switch
T-K3 Part # #409 Takagi Part # EK N3 4 Checkpoint
C1
Function
Failure event
Effects on the T-K3
if hi-limit switch fails.
111 121
Diagn ostic
Color/Number of
wires
Blu e-Blue
When temperatures exceed 194˚F (90˚C), the reset button trips and switch goes to OFF mode.
ON mode : <194˚F (90˚C) OFF mode : to reset switch back to ON mode, press the reset button
Error codes when
hi-limit switch fails.
Less than 1Ω
1. Visu al i nsp ection : co nnection/breakage of wir es. Possibility also includes scale
deposits inside the hea t exchanger .
2. Check voltages an d re sistance: proper range of values shown belo w.
-Based on bi-metal therma l expansi on.
-Detects exce ssively high water tempe rature (more than 194˚F or 90
˚
C) in pipes of the
heat exchanger .
-After detection, communication between the computer boar d a nd g as valves are severed,
shutting d own the T-K3 instantly. The "111" or "121" error codes will display.
1. Unable to detect excessively hig h water temperatures if switch fails "closed".
2. Continu ous d etection of e xcessivel y high water temperature s (regardless of what the
actual wa ter tempera ture is) if switch fails "op en".
1. Unable to shut d own the T-K3 if the water temperature from the h eat exchang er
exceeds 194˚F (90 ˚C).
Note: The mixing and outlet thermistors always act as backup h i-limit detectors to detect
excessively h igh water temperature s in the heat exchange r.
2. The T-K3 is always shut down immediately after the ignition process, and ei ther the
"111" or "121" error code will display.
The T-K3 doesn't have the "141" error code that was use d in our previous m odels.
This error c ode is now re place d by the "111" and the "121" error codes.
1-3/8" (35mm )
5/8" ( 15m m)
3/4" ( 18.4 mm)
Reset Button
To Next Page
Loading...
Need help?
General
