Bosch Short Cycling

Boiler frequently cycles on and off with short run times, even when heating is needed.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Oversized boiler for system, Poor system circulation, Incorrect control settings, Faulty room thermostat placement, Blocked or undersized bypass

Safety: No special hazards beyond normal; do not open sealed combustion components.

Steps:

Ensure enough radiators are open to absorb the boiler's output.
Check that thermostatic radiator valves are not all nearly closed.
Review room thermostat location; avoid placing it near heat sources or in direct sunlight.
On Bosch controls, enable modulation/weather compensation if available and appropriate.

If cycling persists, a heating engineer should check system design, bypass arrangements, and boiler settings.

Medium 3/5

Bypass Valve / Controls

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