BoilerBuddy · homeowner guide
Why is there no hot water from my boiler?
No hot water can mean the issue affects every tap, one outlet, the boiler controls or the hot-water system. Start by noticing what still works; that helps narrow the next step without guessing at a failed part.
Similar symptoms can have different explanations. The possibilities below are not a diagnosis.
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Understand the symptom
What might be behind it?
A user setting or schedule may not be calling for hot water at the time you expect.
A supply interruption, such as a wider power or water issue, can affect what the boiler can do.
A boiler or hot-water-system fault is also possible. The same symptom can have different causes on combi, system and regular boilers.
Safe observations
Checks you can make without opening the boiler
- 1
Check whether the issue affects one hot tap or every hot tap, and whether cold water still flows normally.
- 2
Look at the normal user controls and schedule. Change a setting only as described in the controls’ own instructions.
- 3
Note whether the boiler display is on and record any code exactly as shown. Do not reset it repeatedly or open the casing.
Know when to stop
Stop if you notice
- A smell of gas, or a yellow, orange or sooty flame.
- A carbon monoxide alarm is sounding, or someone has possible CO symptoms.
- Smoke, scorching, visible damage, overheating or a leak around the boiler.
- The boiler keeps locking out or will not stay lit.
What not to touch
Do not remove the casing, inspect internal valves or wiring, open a hot-water cylinder, or work on gas, burner or flue components. Do not treat a guessed fault-code meaning as confirmed.
When to contact a Gas Safe engineer
Contact a Gas Safe engineer if the problem continues after a simple user-control check, returns repeatedly, or the boiler displays a fault. Use the emergency flow first for gas-smell or carbon-monoxide warning signs.
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Get help that matches what you can see
If you do not know the fault code or exact model, start with the symptom check. Record any displayed code from the screen without opening the boiler casing.
Official safety sources
HSE guidance says not to use an appliance you suspect is unsafe and that domestic gas work must be carried out by a Gas Safe registered engineer. Follow the emergency guidance if you suspect a gas leak or carbon monoxide exposure.
Need a qualified engineer?
BoilerBuddy can pass what you've worked out to a local Gas Safe engineer — symptoms, checks, and the bits that point to the likely cause.
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Engineer handover
Send this sheet with you to the visit.
Print or email it to your engineer so they arrive already knowing what your boiler is doing and what you've already tried.