Support & troubleshooting
Written for the distributors, installers and end users of our instant water heater ranges (tankless and compact series). Nine out of ten service calls are one of the faults below, and most of them are fixed in minutes without opening the unit. Work through the table, check the display codes, and only send a unit to service when the fault is still there.
The same fault table our own service desk works from. Causes are listed most-likely first.
| Symptom | Likely cause | What to do |
|---|---|---|
| Water leakage | Poor connection of the inlet or outlet pipe; damaged rubber gasket at the joint; in rare cases, leakage inside the heater. | Re-connect the pipes and replace the rubber gasket. If water escapes from inside the housing, stop using the unit and contact your distributor for service — do not open the heater yourself. |
| Control keys do not respond | The keypad is working in a damp or electrically noisy environment. | Ventilate and dry the installation space, then power the unit down and restart it once the power supply is stable. If the keys stay dead, the membrane or control board needs replacing — spare parts come through your distributor. |
| Water too hot or scalding | Flow rate too small for the selected power, or the pipeline is partly blocked. | Increase the water flow with the valve, lower the gear or the set temperature, and clean the inlet filter screen and shower head. Keep the outlet pointed away from the body and never test the temperature with your hand under the jet. |
| Water not hot enough | Flow rate too large or gear too low; supply voltage lower than rated; flow sensor restricted by foreign matter. | Reduce the flow or select a higher gear; check that the supply voltage matches the rating on the label; have the flow sensor cleaned if it is stuck. |
| Temperature swings hot and cold | Unstable supply voltage or unstable water pressure. | Normal function — the temperature returns when the supply does. Fit a constant-pressure or booster pump where pressure varies, and keep the heater on its own circuit where voltage sags. |
| Flow getting weaker over time | The water filter or the shower head is blocked by sand or scale in the supply. | Remove the water pipe and clean the filter, then clean or descale the shower head. In hard-water areas, repeat once or twice a year. |
| Leakage (RCD / ELCB) switch trips | Genuine earth leakage; an ageing or under-rated leakage switch; the switch current too small for the heater; or the unit mounted upside down. | Switch off and isolate at once. Do not reset it repeatedly, bypass it, or fit a higher-rated device. Have a qualified electrician clear the fault, check the switch rating against the heater power, and confirm the unit is installed vertically. |
| Display shows a code (E0 / E1 / E2 / Er) | The machine has detected a sensor, flow or installation fault — see the code list below. | Follow the action for that code. Contact your distributor or service if the code stays after the fix. |
| Display does not light up | The power supply is not connected; or the unit has cut out on its dry-fire / overheat protection. | Close the switch and restore power. If the unit had no water flowing when switched on, restore the water supply first, then power it again. |
Stop and disconnect if the fault persists. If a fault cannot be cleared with the steps above, switch off the control power and contact your distributor, or send the unit to local after-sales service. In particular: a heater that leaks water from inside its housing, or trips a leakage switch more than once, must be taken out of use until it has been checked.
Display codes
Four codes cover everything our tankless and compact ranges can show. A code is a diagnosis, not a breakdown — each one points at a single check.
The outlet temperature sensor is short-circuited. Power down and contact service or your distributor — the NTC sensor needs checking and replacing.
The sensor or its wiring is broken. Same action: the sensor circuit must be checked and the sensor replaced by service.
More water is passing through than the selected power can heat. Adjust the water valve to reduce the flow and the code clears itself.
The machine detects that it is not vertical. Re-mount the heater vertically — it is designed to work only in the upright position.
Most “faults” reported on first installation turn out to be wiring or water supply. These two tables settle it on the spot.
| Rated power | Current, 220–240 V~ | Min. conductor |
|---|---|---|
| 3.5 kW | 15–16 A | 1.5 mm² |
| 4.5 kW | 19–21 A | 2.5 mm² |
| 5.5 kW | 23–25 A | 2.5 mm² |
| 6.0–7.0 kW | 27–32 A | 6.0 mm² |
| 8.0–8.8 kW | 36–40 A | 6.0 mm² |
| 11 kW | 46–50 A | 10 mm² |
Water pressure: 0.1–0.6 MPa, or 0.1–0.8 MPa for the cast-aluminium element models — below 0.1 MPa the heater may not start; above the upper limit for your element type (0.6 MPa stainless steel, 0.8 MPa cast aluminium) fit a pressure-reducing valve. Voltage: as marked on the rating plate (220–240 V~ or 110 V~); a 110 V model and a 220–240 V model are not interchangeable. For 110 V models the conductor size, overcurrent device and RCD must be selected by a qualified electrician from the rated current and local wiring rules. The conductor sizes above are minimum values for copper conductors in a typical installation — the installer is responsible for the final selection.
Field questions
A leakage switch that trips is a warning, not a nuisance. The most common causes are a genuine earth leakage in the unit, an ageing or under-rated leakage switch, or the heater being mounted upside down. Switch off and isolate: do not reset it repeatedly, bypass it, or fit a higher-rated device. Have a qualified electrician clear the fault and replace the switch with a correctly rated one, confirm the unit is installed vertically, and if the tripping continues send the unit to after-sales service.
An instant heater has a fixed power, so water temperature depends on flow: the more water passes through per minute, the smaller the temperature rise. Open the water valve less to reduce the flow, or raise the gear or the setpoint on the control panel. Also check the supply voltage, because a heater rated at a lower voltage than the mains will never reach its rated output. If the flow sensor is stuck or entangled by foreign matter, have it cleaned.
Too-hot water means the flow through the heater is too small for the selected power. Increase the water flow, reduce the heating gear or set a lower target temperature, and clean the inlet filter screen and the shower head, which are often partly blocked by sediment. On machines with a flow sensor, a partly blocked inlet makes the display show a higher temperature than the mixed water actually is.
Unstable voltage or unstable water pressure. When either supply fluctuates, the outlet temperature swings with it, and returns to normal when the supply does. Where the mains pressure varies through the day, a constant-pressure or booster pump keeps the flow steady; where the voltage sags when large appliances start, put the heater on a dedicated circuit.
The water filter or the shower head is blocked by sand and scale carried in the supply. Remove the water pipe and clean the filter, and soak or brush the shower head. In hard-water areas this is routine maintenance, not a fault, and doing it once or twice a year keeps the heater sensing flow correctly.
E0 means the NTC temperature sensor is short-circuited and E1 means it is open-circuit; in both cases the sensor must be checked and replaced by service. E2 means the water flow is excessive, so reduce the flow with the water valve. Er is a reminder that the unit is installed in the wrong direction and must be re-mounted vertically. If a code stays after these checks, contact after-sales service or your distributor.
Distributors get the complete factory operating manual with every order, and spare parts — sensors, gaskets, switches, control boards — are stocked for the whole range. Tell us the model and the fault and we will point you at the right part.
Download the factory manual as a pocket-size PDF (105 × 140 mm, 8 pages):
