How it shows on your panel
- CP Classic (the turn-knob panel): yellow blinks ×4 (or ×6 if it's the water-only version).
- CP Plus (the screen panel): a code — W18H / E18H / E121H / E150H for airflow, or E151H / E152H for water too hot.
Fix 1 — clear the airflow (the most common cause)
The warm-air outlets are the vents low down around the furniture and floor, and the heater pulls air back in through a larger intake grille. If bedding, bags, or clothes are covering the outlets or the intake, warm air can't circulate and the heater overheats and cuts out.
- Clear anything sitting on or in front of the outlet vents and the intake grille.
- Check the floor ducts aren't crushed, kinked, or disconnected.
Fix 2 — check the water side (if you're heating water — this is the E151H / E152H case)
If hot water is running while the fresh-water tank is empty, the boiler has nothing to heat, overheats, and shuts down.
- Switch the heater off and let it cool for a few minutes.
- Top up the fresh-water tank so the boiler can fill.
- Don't run water heating with an empty tank.
Then reset
Switch the panel off, wait 5 seconds (give it a few minutes to cool if it was over-temp), and switch it back on. The ×4 blink or the code should clear and the heater restart.
(Image: where the warm-air outlet sits)
Still showing the error?
- 💬 WhatsApp — message us here
- 📞 Call us — available in your rental agreement