HVACopedia

FlowMax · Combi boiler

28 Legionella prevention cycle active

Normal status FlowMax condensing combi (FLOWMAX-120)

What the display is showing

Code 28 shows while the legionella prevention function runs. It exists only for models with a hot water storage cylinder. Every 7 days it raises the cylinder to 60 C whatever hot water temperature is set. This is a normal scheduled cycle.

Applies to: FLOWMAX-120 with storage cylinder

Settings for these units

Other codes on the same units

  • 07 Flue test (chimney sweeper) function active
  • 08 Frost protection active
  • 22 Fan frequency readout (parameter 22)
  • Curve number Compensation curve number display
  • OFF Switched off, frost protection still active
  • PL 0 Parameter menu entered

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Source: FLOWMAX-120 Instruction Manual, 6.11 Diagnostics - Function codes, p.68. Summarized in our own words; check the original manual for your model.

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.