The boiler frequently cycles on and off; radiators get hot then cool quickly, and the room never reaches the set temperature.

Safety first: Cycling itself is not immediately dangerous but can reduce efficiency and lifespan.

• Check controls: Ensure the room thermostat is correctly located (not above a radiator or in direct sunlight) and set appropriately.
• Open more radiators: Avoid closing too many TRVs; the boiler needs sufficient flow.
• Check bypass: If you have an automatic bypass valve, ensure it is set according to the manufacturer's instructions (engineer task).
• Engineer tasks: An engineer can adjust pump speed, optimise control settings (e.g., weather compensation), and advise on system balancing.