Pump Control Mode - Takagi T‐H2‐DV Installation Manual And Owner's Manual

The T‐H2‐DV/T‐H2‐OS provides the four types of the pump control
modes. The pump control modes are selected by changing
dipswitch settings. The dipswitches that change the pump control
modes are located in the right bank of dipswitches in the upper‐
left quadrant of the computer board in the T‐H2‐DV/T‐H2‐OS. (See
right.) These 4 modes only affect pumps that are connected to
the T‐H2‐DV/T‐H2‐OS pump control (p.25)
A) Recirculation Control: No. 5 ON
Feature: Maintaining temperature in a standard recirculation loop, providing hot water in a quicker
amount of time.
Function: The pump is only set to run when the temperature of the water in the recirculation loop is
more than 9°F below the set temperature of the T‐H2‐DV/T‐H2‐OS.
The pump will run for about 1 minute every 30 minutes to determine whether the water
temperature in the entire recirculation loop is more than 9°F below the set temperature.
If the water temperature is more than 9°F below the set temperature, the pump will remain running
until the water in the loop reaches the set temperature. Otherwise, the pump will stop for another
30 minutes.
If the inlet thermistor of water heaters detects that the water temperature is more than 9°F below
the set temperature before those 30 minutes have elapsed, the pump will activate immediately and
remain running until the water in the loop reaches the set temperature.
B) Storage Tank Circulation Control: No.6 ON
Feature: This is to ensure a higher rate of recovery for storage tank applications.
Function: The T‐H2‐DV/T‐H2‐OS heats the water 5.4°F higher than its set temperature. The
circulation pump between the storage tank and the water heater will continually remain running.
After set temperature has been reached in the storage tank, the T‐H2‐DV/T‐H2‐OS will fire off and
limit the water flow rate to less than 2.6 GPM, to continually monitor the temperature throughout
the system.
Note: In this mode, the pump will continually remain running.
C) Energy Conserving Recirculation: No.5 and No.6 ON
Feature: Operates similarly to the standard Recirculation Control mode, but saves more energy by
limiting the temperature within the recirculation loop.
Function: The temperature of the recirculation loop is never kept above 120°F (49 °C), regardless of
the set temperature of the T‐H2‐DV/T‐H2‐OS.
PUMP CONTROL MODES
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Installation
Right bank of dipswitches