HVACopediaBosch · Boiler · Other
Thermal disinfection of DHW tank
What happens, in order
- Close all DHW taps and set any recirculation pump to continuous
- Turn the DHW thermostat to max (about 158 F / 70 C) and wait for the tank to reach it
- Open every tap, nearest first, and run until 158 F (70 C) or more for at least 3 minutes at each
- Return thermostat, recirculation pump and heating control to normal
- Service function 2.d (00 off, 01 on) can run it automatically
Timings and thresholds
| Item | Value |
|---|---|
| Disinfection temperature | 158 F (70 C) |
| Time at each tap | at least 3 min |
Applies to: ZBR with DHW tank
Models
More Bosch boiler sequences
- First power-up purge and trap filling · Startup
- Heating call, anti-cycle and pump post purge · Heating
- Combi comfort and economy modes · Domestic hot water
- Tank priority (ZBR with DHW tank) · Domestic hot water
- Frost protection setup · Freeze protection
Related
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Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Bosch Greenstar 6721853955 (2025-11) and 6721853953 (2025-11), Heatronic service functions and operation sections. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.