Stiebel Eltron heat pump water heater

Stiebel Eltron Accelera 300 (no controls) error codes

Covers: Accelera 300 (earlier 80-gallon model without user controls; type plate 'Accelera 300/WHP 300')

Every code listed in Stiebel Eltron's own manual for this series, with what it means and what Stiebel Eltron says to do. Last checked 2026-10-03.

Is this your model? The earlier 80-gallon Accelera 300 (type plate "Accelera 300/WHP 300"). Its manual says the heater has no controls, so it shows no codes.

Stiebel Eltron's manual for this series does not list error codes; see the troubleshooting section below.

Troubleshooting without a code

• The water heater does not deliver hot water

  What to do: Check the water heater power supply. Check your fuse box for a tripped circuit breaker. Make sure there is a 15 A double pole circuit breaker. If the circuit breaker has tripped, reset it or replace it. Notify your local licensed installer if the circuit breaker trips again. Ensure that the air intake and air discharge are unobstructed.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• The water heater does not deliver hot water

  Likely cause: Excessively high ambient temperature, excessively high temperature of the air drawn in (> 42 °C (108 °F)) or a fault in the refrigerant circuit can result in the compressor being overloaded. The thermal protective 'auto reset' motor switch or the high limit 'manual reset' cut-out can both shut off the compressor.

  What to do: The high limit pressure limiter must only be reset by your licensed installer after they have removed the cause of the relevant fault. After a short cooling down period, the thermal protective motor auto reset switch will restart the compressor automatically. Notify your local licensed installer if the water heater does not restart automatically.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• The safety valve of the cold water supply line is dripping

  Likely cause: Expansion water drips from the safety valve during heat-up. This is completely normal.

  What to do: Notify your local licensed installer if water still drips after heat-up has been completed.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• The condensate drain drips

  Likely cause: This is quite normal and always happens when the surface temperature of the evaporator is lower than the dew point temperature of the ambient air.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• The power consumption is too high

  What to do: Please consult a qualified licensed installer.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• The room temperature drops excessively

  Likely cause: The water heater operation reduces the ambient air by 1 to 3 °C (2 to 6 °F).

  What to do: Notify your local licensed installer if the ambient temperature drops abnormally.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• Other faults occur

  What to do: Notify your local licensed installer. Refer to the water heater number on the type plate next to the barcode.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• Excessive power consumption (installer section) (installer section of the manual)

  What to do: Lower the temperature of the booster heater.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 23

• The room temperature falls excessively (installer section) (installer section of the manual)

  Likely cause: One possible cause is an inadequate air flow over the evaporator.

  What to do: Check the fan. Check for clogged evaporator. Ensure that the intake and discharge flow are not restricted.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 23

Owner maintenance

• exterior cleaning

  A damp cloth is sufficient for cleaning the exterior of the water heater. Never use abrasive or corrosive cleaning agents. Do not hose down the water heater.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 11

• condensate drain

  How often: monthly

  Monthly, check that the condensate drain is clear. Monthly, carry out a visual inspection of the condensate pan drain (in the top of the water heater) by looking through the air intake grille at the front. If required, notify your local licensed installer who will remove any contamination.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 11

• descaling booster heater

  How often: from time to time

  Have a licensed installer descale the booster heater from time to time. A licensed installer who knows the local water quality will tell you when the next maintenance appointment is due.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 12

• anode

  How often: check no later than 12 months after initial start-up (timing determined by local licensed installer)

  Have your licensed installer check the sacrificial anode regularly (pg. 12). If the anode is used up, it must be replaced; if a full-length anode rod (approx. 1260 mm / 50") cannot be installed, install a segmented anode (installer section, pg. 24).

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 24

• clean evaporator (installer section)

  How often: occasional professional cleaning

  Undo the screws that connect the water heater cover and remove. Carefully clean the evaporator fins. Only use water and a soft brush. Never use acidic or alkaline cleaning agents.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 24

• draining (installer section)

  Close the shut-off valve in the cold water line. Fully open the hot faucets at all points. Open the drain valve (or undo the fitting on the cold water supply). Some residual water will remain in the bottom of the tank.

  Source: Accelera 300 Heat Pump Water Heater - Operation and Installation, A 280011-38683-9053, page 24

Sources

• Accelera 300 Heat Pump Water Heater - Operation and Installation (A 280011-38683-9053)