- Boilers
- Electric water heater
W30
Thermor W30.1 water heater code: heat pump heating too slowly
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On Thermor heat pump water heaters, W30.1 (or error 30) means the heat pump took over 30 hours to heat the tank or is heating far too slowly. Check air inlets, possible hot water leaks and the operating mode; refrigerant work is for a certified technician.
Safety first
Stop and check this first
- Before anyone opens the casing to check the fan or evaporator, the water heater's breaker must be switched off at the consumer unit; do not remove covers while the unit is powered.
- Only a certified refrigeration technician may open the heat pump circuit; never try to recharge it or hunt for refrigerant leaks yourself, even if W30.1 keeps coming back.
Safe checks you can perform
- Pick a mode that uses the element
- Look at the air inlets and outlets
- Water meter test to rule out leaks
- Listen for the fan
Leave these tasks to a qualified professional
- Do not attempt this professional task: Review the plumbing layout
- Do not attempt this professional task: Clean the evaporator and check the fan
- Do not attempt this professional task: Measure heat exchange and refrigerant charge
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Review the plumbing layout
What they doThe installer checks whether the tank is fed from a recirculation loop or a charge pump and whether its size suits the number of occupants.
They must show youhow the hot water side is piped to the tank.
In writingthe change proposed to the installation and why.
Clean the evaporator and check the fan
What they doWith the power isolated, the installer opens the unit, cleans the evaporator as Thermor's maintenance requires and checks that the fan starts.
They must show youthe evaporator before and after cleaning.
In writingwhat was cleaned and whether the fan was working.
Measure heat exchange and refrigerant charge
What they doA refrigeration technician checks that the air leaves about 10 °C colder than it enters and, if not, looks for leaks and restores the charge stated on the rating plate.
They must show youthe inlet and outlet air temperatures they measured.
In writingrefrigerant recovered or added and whether a leak was found.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Pick a mode that uses the element
Look at which mode the control shows. Thermor says that in Manual ECO active or ECO the element stays off (except on Airlis) and you get no hot water while W30.1 is present; switch to AUTO, Manual ECO inactive or the emergency mode described in your model's manual.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Look at the air inlets and outlets
Without removing any cover, make sure nothing blocks the grilles or air openings or the ducts if fitted: boxes, laundry, built up dust or a crushed duct. Take a photo of what you find for the installer.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Water meter test to rule out leaks
Close every tap and make sure no appliance is drawing water. Note the meter reading and look again a few minutes later. If the figures move with nothing running, there is a leak your installer must find and repair.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Listen for the fan
With the heat pump running, stand close without opening the unit and listen whether the fan turns normally and quietly. If you cannot hear it or it sounds wrong, leave it alone, note it and book a professional visit.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Thermor
- Product type
- Electric water heater
Known code variants
- 30
- 30.1
- Aéromax W30.1
- Airlis 30.1
- Err 30
- Erreur 30
- Thermor W30.1
- W.30.1
- W30
- W30.1
What it means
Thermor's FAQ says W30.1, error 30 or, on some controls, error 10 appears when heat pump heating lasts more than 30 hours, is inefficient or does not happen at all. To prevent irreversible damage the unit stops the heat pump. It applies to Aéromax 2 to 6, RT+, VMC, Access, Split 1 to 3 and Airlis (shown there as 4 flashes of the fan symbol). Depending on the mode you keep some hot water from the backup element or none at all. The code does not identify a part: the cause can be in the installation, the maintenance or the refrigerant circuit.
Warnings and stop conditions
- Higheditorial warning
Before anyone opens the casing to check the fan or evaporator, the water heater's breaker must be switched off at the consumer unit; do not remove covers while the unit is powered.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
- Highsource verified
Only a certified refrigeration technician may open the heat pump circuit; never try to recharge it or hunt for refrigerant leaks yourself, even if W30.1 keeps coming back.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Symptoms and causes
Probable causes · in order
- Blocked air inlets or poor installationCommon
Thermor asks you to make sure the air inlets are not obstructed and that the installation follows the manual; with too little airflow the heat pump cannot collect enough heat.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
- Dirty evaporator from lack of maintenanceCommon
The fan draws dust and moisture through the evaporator; once it is clogged it loses efficiency and the heat pump needs many more hours to reach temperature.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
- Leak on the hot water pipeworkPossible
If a hot water pipe is leaking, cold water keeps entering the tank and the heat pump runs for hours without ever reaching the set point.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
- Recirculation loop or tank too small for demandPossible
Thermor advises against connecting the tank straight to a charge pump or a hot water loop, and warns that a capacity too small for the household keeps the heat pump running until the error trips.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
- Fan not turning or refrigerant shortagePossible
A fan that does not spin or a low refrigerant charge, from installation or over the years, reduces the air temperature drop that Thermor puts at about 10 °C. A professional diagnoses it.
Evidence: Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Virtual technician
Does W30 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Mon chauffe-eau affiche une erreur, que faire ?
Thermor · 2025 · official_doc
- 2
Comment résoudre un problème de chauffe-eau qui affiche une erreur 30 ou W30.1 ?
Thermor · 2025 · official_doc
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