Radson fault code A4
Fault code A4 on a Radson boiler (including Radostar) means: The flue gas protection has been activated and the burner stops 1 min 30 s after commissioning. Reset the appliance once. If the code comes back, a part is usually faulty. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code A4 on a Radson boiler indicates: The flue gas protection has been activated and the burner stops 1 min 30 s after commissioning.
Fixing fault code A4: step by step
- Check outside that the air intake and flue are clear (leaves, a nest, ice or snow).
- Check that the condensate trap under the appliance is filled and clean; a blocked condensate drain can make the boiler lock out.
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the code comes back, stop resetting: a flue problem can let carbon monoxide (CO) into the home. Call in a qualified heating engineer and make sure you have a working CO alarm.
Applies to
Radson Radostar, EHLE 17, EHLE 23, EHLE 27, EHLE 34, EHLE 39, EHLE 78.
Click a model for the parts list and exploded view of that appliance.
Matching parts
Radson parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
For fault code A4, the part involved is usually in the category: burner.
This message does not point directly to one faulty part. These are the parts that most often fit this appliance:
- Bosch gasket for e.g. EHLE 23 87168336790 € 26.51
- Nefit maximum thermostat Clixon € 33.98
- Bosch plug for NTC € 33.98
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does Radson boiler fault code A4 mean?
The flue gas protection has been activated and the burner stops 1 min 30 s after commissioning.
How do I fix fault code A4 on a Radson boiler?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for Radson fault code A4?
That depends on the exact cause. In the Radson parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code A4 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All Radson boiler faults and codes at a glance →