BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water pressure is too low for it to operate safely and has shut down.
Locate the filling loop (a flexible silver hose) underneath or near the boiler.Slowly open the valve(s) to allow water into the system while watching the pressure gauge.Close the valve(s) tightly once the pressure reaches between 1.0 and 1.5 bar.
Your boiler has detected that the water pressure is too low for it to operate safely and has shut down to avoid damage.
Locate the pressure gauge on the front of the boiler or underneath it.Find the filling loop, which is usually a flexible silver hose with one or two small black taps.Slowly open the taps until the pressure gauge needle sits between 1.0 and 1.5 bar.Securely close both taps and attempt to reset the boiler.
Your boiler's electronic settings have been disrupted by outside electrical interference, causing the system to stop working properly.
Locate the reset button on the control panel.Press and hold the reset button for 5 seconds.Wait 2 minutes to see if the boiler resumes normal operation; if the code persists, a professional must recalibrate the settings.
Your boiler is struggling to move water around the system correctly, which is preventing it from heating up properly.
Check that your boiler pressure is between 1.0 and 1.5 barEnsure all radiator valves and internal stop taps are fully openBleed your radiators to remove any trapped air pockets
Your boiler is overheating because water isn't moving through the system quickly enough to carry the heat away.
Check that your boiler pressure is between 1.0 and 1.5 bar on the gaugeEnsure all radiator valves and isolation valves are fully openBleed all radiators to remove trapped air that might be blocking flow
Your boiler has shut down because it has detected it is getting too hot, likely due to a lack of water flow through the system.
Check that all radiator valves are fully openEnsure the boiler pressure gauge is between 1.0 and 1.5 barPress the reset button to see if the fault clears after the system cools down
on the Unical Alkon R 28 HE
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Unical shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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