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C3 on Potterton Envoy 30

Your boiler is briefly pausing itself to prevent the system from turning on and off too frequently, which helps protect the internal parts from unnecessary wear.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Boiler restart delayed to prevent rapid cycling. (Max. delay time is 5 mm)

What causes this fault?

This occurs when your thermostat tells the boiler to turn on too soon after it has just finished a heating cycle. To protect the internal components from the strain of constantly stopping and starting, the boiler forces a short pause to let the system stabilise. It is often caused by the radiators reaching their target temperature very quickly or a thermostat being set very close to the current room temperature.

This is more common during the milder 'shoulder' months of spring and autumn when the heating isn't needed constantly but kicks in for short bursts.

DIY fix possible

Wait for 5 minutes for the countdown to completeEnsure radiators are turned on to allow heat to circulateCheck that the room thermostat is set to a temperature higher than the current room temperature

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