Why Is My Boiler Not Heating? Common Faults and Next Steps

A boiler that is not heating radiators can be frustrating, especially when hot water may still work. The cause can be as simple as a control setting or as complex as a failed pump, valve or internal component.

This guide explains common reasons a boiler may not heat the home and what you can safely check before arranging a repair.

Check the controls first

Confirm that the thermostat is calling for heat, the programmer is set correctly and the boiler is not in hot-water-only mode. Batteries in some thermostats can also fail.

If the controls were recently changed, note exactly what was altered. This helps the engineer understand whether the issue began after a setting or wiring change.

Check boiler pressure

Low pressure can stop a sealed heating system from circulating properly. Read the gauge when the system is cool and compare it with the boiler manual.

If pressure repeatedly drops after topping up, there may be a leak or component fault. Read CoziKent's guidance and arrange an inspection through the boiler repairs page if it keeps happening.

Look for fault codes

Modern boilers often show a fault code when they lock out. Write the code down before resetting. The code helps narrow the diagnosis but does not always identify the exact failed part.

Do not keep resetting a boiler that locks out again. Repeated resets can hide the pattern of the fault.

Common heating faults

Possible causes include:

• A stuck diverter valve.
• A faulty pump.
• Air in the system.
• A blocked filter.
• A thermostat fault.
• A circulation problem.
• Sludge in radiators and pipework.

These faults need proper testing. Do not remove the boiler casing or attempt internal repairs.

When to call an engineer

Call for help if there is no heating, repeated lockout, leaks, unusual noises, low pressure or a fault code that returns. CoziKent provides boiler repairs across Canterbury, Ashford, Whitstable, Herne Bay, Faversham, Dover, Folkestone, Sandwich and surrounding East Kent areas.

The fixed boiler-repair call-out fee is £84 including VAT (£70 + VAT). Same-day attendance may be available when the diary allows.

Local boiler repairs and servicing support

CoziKent is based in Canterbury and works across Canterbury, Ashford, Whitstable, Herne Bay, Faversham, Dover, Folkestone, Sandwich and surrounding East Kent areas. This local coverage helps customers get a clear appointment, practical advice and a realistic explanation of what happens next.

Once the fault is resolved, routine boiler servicing can support safe operation and early fault detection.

What to have ready before you call

Before booking a repair visit, annual service or boiler check, gather a few details. This makes the conversation quicker and gives the engineer a better chance of preparing properly.

• The boiler make and model, if visible without removing the casing.
• The exact fault code, pressure reading or symptom.
• Whether heating, hot water or both have stopped working.
• When the issue started and whether it is constant or intermittent.
• Any leak, unusual noise, recent work or vulnerable person affected by loss of heating.

Important gas safety advice

Do not remove a boiler casing, interfere with gas components or attempt internal repairs.

If there is a smell of gas, suspected carbon monoxide, smoke, fire or immediate danger, leave the property and call the National Gas Emergency Service on 0800 111 999 before contacting a repair company.

Frequently asked questions

Why do I have hot water but no heating?

Possible causes include controls, a diverter valve, pump issue or circulation fault. An engineer can test the system.

Can low pressure stop radiators heating?

Yes. Low pressure can stop circulation and cause lockouts.

Should I reset the boiler?

Follow the manual once if appropriate. If the fault returns, stop resetting and call an engineer.

Does CoziKent repair boilers not heating in East Kent?

Yes. CoziKent covers Canterbury and East Kent.

Call CoziKent

If your boiler is not heating, Call Now on 07535 616484.

Gas Safe registration 666330. CoziKent covers Canterbury, Ashford, Whitstable, Herne Bay, Faversham, Dover, Folkestone, Sandwich and surrounding East Kent areas.