Boiler cycles on and off rapidly when only a small radiator or towel rail is open

Safety first: Avoid covering radiators or blocking ventilation around the boiler.

• Open more radiators: Increase the number of radiators in use to provide sufficient load.
• Lower flow temperature: Reducing CH flow temperature can help reduce cycling.
• Engineer solutions: The engineer may fit or adjust an automatic bypass valve, rebalance the system, and adjust boiler parameters (where allowed) to better match the system.