Bosch Tankless Water Heater: Purge the exhaust circuit (P9 menu)
Purge the exhaust circuit (P9 menu) on a Bosch tankless water heater: About 2 seconds after entering the menu the fan starts and keeps running until the menu is left.
Applies to: Greentherm T9800 SE 160/199 and T9900 SE 160/199 tankless water heaters
How to fix purge the exhaust circuit (p9 menu): step by step
- Open Information / Adjustments, touch until P9 Purge shows
- Touch the symbol to start; the fan starts after about 2 seconds
- Exit the menu to stop the fan
If the unit shows an error code, look it up: Bosch Tankless Water Heater codes
Models
Bosch Greentherm T9800 SE
Greentherm T9800 SE 160Greentherm T9800 SE 199Greentherm T9800 SEC 199
Bosch Greentherm T9900 SE
Greentherm T9900 i 199Greentherm T9900 SE 160Greentherm T9900 SE 199
Source: Bosch Greentherm T9800 SE 160-199 installation 6720816815 (06.2023), 6.5.4 P9 Purge p.52; T9900 SE 160-199 installation 6 720 813 635 (2024-06) same section. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.