A.01.21 error code
A.01.21 – Remeha Gas 220 Ace 160–300 error code
What does Remeha Gas 220 Ace 160–300 floor-standing gas boiler range A.01.21 mean?
Remeha documents A.01.21 for the Gas 220 Ace 160–300 range as “Maximum DHW temperature gradient level 3 exceeded”. It is a warning code on the Gas 220 Ace e-Smart control platform.
The code identifies the condition detected by the product; it does not always identify the failed component on its own. Confirm the full code and exact model before ordering parts or attempting a reset.
The Remeha Gas 220 Ace 160–300 floor-standing gas boiler range A.01.21 error code indicates remeha documents A.01.21 for the Gas 220 Ace 160–300 range as “Maximum DHW temperature gradient level 3 exceeded”. It is a warning code on the Gas 220 Ace e-Smart control platform. This guide explains what the code means, the symptoms and likely causes, the checks that are safe to make, and when to stop and arrange an authorised repair.
Symptoms you may notice
The control panel displays A.01.21. The boiler can continue operating while the cause is investigated.
Common causes
The controller detected a sensor, temperature, pressure, circulation or related wiring condition. The exact failed part cannot be confirmed from the display alone.
Before you start troubleshooting
Use the display, rating label or product menu to confirm the exact model. Similar-looking codes can have different meanings across product generations and regions.
- Record the complete code before switching the equipment off.
- Check only user-accessible controls, filters and external connections described in the manual.
- Do not open gas, refrigerant, combustion or electrical compartments.
Troubleshooting steps
Record the code and check only user-accessible system pressure and external valve settings. Sensor, circulation, pump, wiring and heat-exchanger checks require a qualified engineer.
Can you fix this error code yourself?
The safest next step depends on the exact model and the cause behind the code. External checks may help, but a returning fault needs professional diagnosis.
A successful reset is not proof that the underlying issue is fixed. If A.01.21 reappears, note when it happens and give that information to the service engineer.
Reset instructions
Warnings do not normally require a reset. Record the code and arrange investigation if it persists or escalates.
Applicable products and models
Gas 220 Ace 160–300 floor-standing gas boiler rangeGas 220 Ace 160; Gas 220 Ace 200; Gas 220 Ace 250; Gas 220 Ace 3002018 service-manual generationWhen to contact a professional
Contact Remeha technical support or a suitably qualified Gas Safe registered commercial heating engineer. Provide the full code, exact Gas 220 Ace model, serial number and recent operating history.
Frequently asked questions
What does Remeha Gas 220 Ace 160–300 floor-standing gas boiler range A.01.21 mean?
Remeha documents A.01.21 for the Gas 220 Ace 160–300 range as “Maximum DHW temperature gradient level 3 exceeded”. It is a warning code on the Gas 220 Ace e-Smart control platform.
Can I fix Remeha Gas 220 Ace 160–300 floor-standing gas boiler range A.01.21 myself?
Some external checks may be suitable for the user, but the result depends on the exact model and cause. Use the official manual and arrange service if the code returns.
Should I reset the product after code A.01.21?
Warnings do not normally require a reset. Record the code and arrange investigation if it persists or escalates.
When should I arrange a repair?
Contact Remeha technical support or a suitably qualified Gas Safe registered commercial heating engineer. Provide the full code, exact Gas 220 Ace model, serial number and recent operating history.