Low
S.24 on Glow-worm Ultracom 24cx 30cx

Your boiler is operating normally; this is a status message indicating that the burner is currently lit and heating your water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

burner on (NORMAL OPERATING STATE FOR PRE-HEAT MODE)

From this model's manual
Verified against the Glow Worm Ultracom 24cx 30cx installation & service manual, page 52.
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 code appears because your boiler is functioning exactly as it should and the burner is currently firing to provide heat. It is simply a status update letting you know that gas is being burned to heat the water for your taps or radiators. You do not need to take any action, as this is a sign of normal operation.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like S.24: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

S.04View →S.34View →

Related guides you might find useful

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

New boiler cost 2026

Realistic UK prices for a swap.

Read →