Takagi T-M50 - Manual (Page 23)

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The dark squares indicate the direction
the dipswitches should be set to.
PUMP CONTROL MODE
The water heater provides the four types of the pump control modes. The pump control modes
are selected by changing dipswitch settings. The dipswitches are located in the upper bank of
dipswitches in the lower-left quadrant of the central computer board in the water heater. (See
picture below)
A) Recirculation Control: No. 4 ON
This mode is for providing hot water as soon as possible like a recirculation usage. The pump
is only made to run while the temperature of the water in the re-circulation loop is not close to
the set temperature of the water heater. The pump will run for about 1 minute every 30
minutes to determine whether or not the water temperature in the whole recirculation loop is
lower than 9°F from the set temperature. If the water temperature is lower than 9°F from the
set temperature, the pump will remain running until the water in the loop gets up to the set
temperature. If not, the pump will stop for another 30 minutes. If the inlet thermistor senses
that the water temperature is lower than 9°F from the set temperature before those 30
minutes have elapsed, the pump will activate immediately and remain running until the water
in the loop gets up to the set temperature.
B) Storage Tank Circulation Control: No.5 ON
The water heater will heat the water 5.4°F higher than its set temperature (unless the water
heater is already set at its maximum temperature of 185°F). This is to ensure a higher rate of
recovery for storage tank applications. The circulation pump (from storage tank to water
heater) will always remain on.
C) Energy Conserving Recirculation: No.4 and No.5 ON
This pump control mode is similar to the “Recirculation Control mode”. However, once the
heat requirement is less than 7,440 BTU/h, the pump will turn off. The pump will activate
again when the temperature of the system is less than 95°F or after 20 minutes have elapsed
from its previous operation.
*If operating the pump in this mode, insulation is recommended on the water piping.
D) Normal Control (Default setting): No.4 and No.5 OFF
This provides no ON/OFF control for the pump. If a pump is connected to the pump control
terminal and both No.4 and No.5 are OFF, the pump will be made to run all the time as long
as there is a power supply to the water heater (If the temperature remote controller is
installed, the pump will stop when the remote is turned off). Water in the loop will be
maintained at set temperature.
O
N
1 2 3 4 5 6 7 8
RE
-CIR
ST
O
R
A
G
E
P-R
E
LP D-P
R
T
B) Storage Tank
Circulation Control
A) Recirculation
Control
C) Energy Conserving
Recirculation
D) Normal Control
Pump control modes
(Default)
O
N
1 2 3 4 5 6 7 8
RE
-CIR
ST
O
R
A
G
E
P-R
E
LP D-P
R
T
O
N
1 2 3 4 5 6 7 8
O
N
1 2 3 4 5 6 7 8
RE-CIR ST
ORAGE P-
R
E
LP D-
P
R
T
Upper bank of
dipswitches
RE-CIR ST
ORAGE P-
R
E
LP D-
PRT