Boiler shows E08, no heating or hot water, pump may not run

Safety first: Isolate power and allow the system to cool before touching the pump or opening any bleed screws.

• Check system pressure: Ensure the pressure gauge on the ACV boiler is within the correct range. Very low pressure can prevent the pump from running.
• Feel the pump: When there is a heat demand, carefully touch the pump body. If it hums but does not vibrate, it may be seized.
• Bleed the pump (if fitted with a screw): Some pumps have a central bleed screw. With a cloth ready, loosen it slightly to release trapped air and a small amount of water, then retighten. Restore power and test.
• Professional service: If the pump remains non-functional or E08 persists, a technician should test the pump electrically and replace the pump or PCB as required.