BOSCH 6720819502 Gas Tankless Water Heater User Guide

Recirculation Pump Kit
7 736 504 585

6720819502 Gas Tankless Water Heater

1. Tankless unit outer cover
2.  External recirculation pump (field supplied)
3.  Line voltage connection to terminal block of accessory cable
4.  5 amp fuse
5.  Recirculation pump kit
6.  Accessory cable connects to tankless control board

External power supply required to power the pump.
External power supply and wiring field supplied.

Domestic hot water recirculation – Indoor models

Direct recirculation through the tankless water heater is permissible, however, the heat exchanger warranty is reduced; see warranty at www.boschheatingandcooling.com.
The following drawings are provided to illustrate two possible recirculation designs. These schematic is for illustration only and must not be used for actual Installation without appropriate engineering and technical advice from a properly licensed professional in the locality where the installation is made.
In order to reduce the heat loss through the pipes, it’s recommended to insulate all the pipes in the recirculation circuit.

Start up procedure

WARNING: Appliance damage!

• Ensure that the water loop is full before activating the recirculation mode.
•  Open a hot and cold water tap to fill the water circuit.
•  Plug-in and turn ON appliance.
•  Open gas supply to appliance.
•  Wait until there is no air in the recirculation loop (a few minutes).
•  Close the taps.
  The recirculation system is now ready to be activated.

Recirculation options

House Recirculation
This recirculation option uses the appliance’s NTC sensor along with the optional schedule to control the pump.
Tank loading
This recirculation option gives the option of using one of three temperature sensors to control the recirculation option. The scheduling option is not available for tank loading, except for commercial models.

• External NTC
  – Only compatible with Bosch cable/sensor accessory (7736504583).

• Aquastat
  – The aquastat connector kit (7736504584) must be used to connect a field supplied aquastat to the appliance.

• Internal NTC
  – Uses the appliance’s NTC sensor to measure the incoming water temperature.

For more information on how to program each menu, see the appliance installation manual.

Recirculation with a dedicated return line

1. Cold water supply
2.  Check valve field supplied
3. Circulator pump field supplied
4. Expansion tank field supplied
5. Circulator cable accessory
6. Greentherm 9800 SE / SEC
7. PRV
8.  Shutoff valves field supplied

Recirculation with a cross over valve

1. Cold water supply
2. Check valve field supplied
3. Expansion tank field supplied
4. Circulator pump field supplied
5. Circulator cable accessory
6.  Greentherm 9800 SE / SEC
7. PRV
8.  Shutoff valves field supplied
9. Cross over valve field supplied

Selecting the recirculation settings
This section only applies to the Greentherm 9000 indoor models.

This menu provides access to several parameters.

•  Touch the symbol to enter the menus.
•  Touch the symbol until the display shows SA Settings.
•  Touch the symbol .
•  Use the symbols or to scroll through the information/adjustments menus, until A1 Recirculation appears in the display.
• Touch the symbol ok to select A1 Recirculation menu.

A1 Recirculation
Choosing a recirculation program:

• Use the symbols or to scroll through the options.
  – HR House Recirculation
  – TL Tank Loading
  – OFF Off

HR House Recirculation

It is recommended to set a schedule that matches use pattern to save energy and improve performance.

Creating a Schedule:

•  Touch the symbol ok , to select Schedule.
•  Touch the symbol ok , to enter the programming menu. Display shows week days.
• Touch the symbol ok , to select a week day.
•  Use the symbols or to choose option Add New.
• Touch the symbol ok , to enter the recirculation program.
•  Use the symbols or to choose the beginning hour.
•  Touch the symbol ok , to set the beginning hour.
•  Use the symbols to choose the end hour.
• Touch the symbol ok , to set the ending hour. A recirculation period is defined. The user can add additional recirculation periods on the same day.
•  Touch the symbol ok , to select Add New and repeat all steps mentioned above.

Copying recirculation program,
The user can copy the recirculation period(s) to other days of the week.

•  Use the symbols or to select the day of the week to be copied.

• Use the symbols or to choose option Copy to.

• Touch the symbol ok .
  Display shows week days.

• Touch the symbol ok to select the day of the week.

•  Use the symbols or to choose another week day. When week days are selected,

• Touch the symbol to validate operation.

• Touch the symbol to exit.

Deleting a recirculation program,

• Use the symbols or to select the day of the week to be deleted.
• Touch the symbol ok .
• Use the symbols or to choose option Delete.
• Touch the symbol ok .
• Use the symbols or to choose a recirculation period.
• Touch the symbol ok twice to delete recirculation period.
• Touch the symbol to exit.

AA Always Active
The recirculation logic will only use the internal NTC to control the recirculation pump.

• Touch the symbol ok to select ON.
  Recirculation will be always active.

TL Tank Loading

• Touch the symbol .
  Display shows following menu.
  – External NTC
  – Internal NTC
  – Aquastat

Select the menu according with the installation.
OFF
Set the OFF:

•  Touch the symbol ok , to select OFF.
  Recirculation will not be active.

Important notes on installation/assembly
The installation/assembly must be carried out by a professional who is authorised to do the work, and with due regard to the relevant regulations.

•  Observe all the relevant instructions for other system components, accessories and spare parts.
•  Before starting any work: disconnect the system from the power supply across all phases.

Original Quality by Bosch Thermotechnik GmbH
Sophienstraße 30-32; D-35576 Wetzlar/Germany
6 720 819 502 (2023/09)

References

• Ling Chang Calendars
• Home | Bosch Home Comfort

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