Medium
On / Off on Worcester Bosch 28i RSF

Your boiler is providing hot water as normal, but there is a communication issue preventing the heating from turning on when you use your thermostat.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Boiler not operating during central heating demand (HW ok)

From this model's manual
Verified against the Worcester Bosch 24i Rsf installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This issue occurs when the link between your heating controls and the boiler is broken, meaning the boiler doesn't 'hear' the signal to turn on. The most common reason is a pair of flat batteries in your wall thermostat or a technical failure in the wireless receiver box attached to the boiler.

This fault is frequently discovered during the first cold snap of autumn when homeowners try to turn their heating on for the first time in several months.

DIY fix possible

Check that the batteries in your wall thermostat or room programmer haven't run outEnsure the heating timer is set to 'ON' or 'AUTO' and the thermostat is turned up higher than the current room temperatureCheck if any wireless receiver attached to the boiler has a power light or is showing a signal connection

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A cover plan would handle faults like On / Off: no call-out fees, no surprise bills.

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