Cold taps where hot water should be, or heating that surges and drops in pressure, usually means a combi-specific fault — call 020 7183 4810 and we’ll get a Gas Safe registered engineer to your Pimlico home. Fixed price agreed before we start, 24/7 emergency cover, and engineers who know the local properties as well as the newer combi installs.
Hot water gone cold? Don’t wait it out.
Same-day combi boiler repairs across Pimlico, fixed price before we start.
Need a Gas Safe engineer today?
Same day callouts across Central and West London, fixed quotes and fully guaranteed work.
Combination boilers do two jobs at once — heating and instant hot water — through one shared set of components, which is why a combi fault often shows up as one working normally while the other fails. Here’s what the common symptoms usually mean and why they’re best left to us.
What your combi boiler is telling you
- Hot water runs cold or lukewarm while heating still works. This points to the part inside the boiler that switches between heating and hot water, or scale build-up choking the hot water side — both very common with London’s hard water.
- Pressure spikes when the heating comes on, then falls away. A worn internal component that cushions pressure changes has likely failed, and the system is venting water externally to compensate.
- Kettling or a rumbling, banging noise. Mineral scale trapped inside the boiler is overheating the water around it. Left alone this tends to end in a cracked internal part rather than a simple fix.
- The boiler won’t ignite, or locks out on the same fault code repeatedly. This sits on the gas and ignition side of the appliance, which only a Gas Safe registered engineer may legally open.
- Water under or behind the casing. Combis pack their electronics close to the plumbing, so any leak here is also an electrical risk.
If you smell gas or suspect carbon monoxide (headaches, nausea, dizziness, a stale smell, or a lazy yellow flame instead of crisp blue), stop. Don’t use switches or naked flames, turn off the gas at the meter if safe, open windows, leave the property and call the National Gas Emergency Service on 0800 111 999, then call us on 020 7183 4810.
Why we don’t recommend the popular online fixes
| The online advice | What actually goes wrong |
|---|---|
| “Top up the pressure and it’ll sort itself out” | Repeated topping-up hides an internal fault that’s venting water somewhere inside the boiler or through an outside pipe — and diagnosing that means opening the casing, which is illegal for anyone except a Gas Safe engineer. |
| “Buy a flush kit and descale it yourself” | Combis have narrow internal waterways that are easy to damage with the wrong chemical strength or a flush done without properly isolating the appliance, and it will usually void your manufacturer warranty. |
| “Keep pressing reset until it fires” | A genuine ignition fault locks the boiler out to stop unburned gas building up. Forcing repeated resets works against that safety feature. |
| “Take the front panel off and have a look” | Under the Gas Safety (Installation and Use) Regulations 1998, only a Gas Safe registered engineer may open a gas boiler. It’s a legal offence otherwise, and it can invalidate your home insurance if anything goes wrong. |
Stop and call us now if…
- You smell gas or suspect a carbon monoxide leak
- Hot water has stopped completely, not just gone lukewarm
- The boiler locks out repeatedly on the same fault code
- There’s water pooling under or around the casing
- The kettling noise has been getting louder over several days
What it costs to wait
A combi fault ignored tends to compound. A slow internal leak can run for weeks before it appears as a damp patch on a ceiling below — which, in a block of flats, can mean an escape-of-water claim, a policy excess, and a dispute with a neighbour or freeholder. Scale left in the heat exchanger is the single most common reason a straightforward repair turns into a full boiler replacement. And any DIY work on the gas or ignition side voids what warranty cover you have left, on top of the safety risk.
How Olia’s Plumbing & Heating handles it
- Diagnose. We read the boiler’s fault history and test the relevant components properly, rather than guessing from the symptom alone.
- Fixed quote. One price agreed with you before any work begins.
- Repair. Genuine manufacturer parts fitted by a Gas Safe registered engineer.
- Test and certify. Full combustion and safety check before we finish.
- Clean finish. No mess left behind.
- Gas Safe registered, 10+ years serving Pimlico combi installs
- 24/7 emergency callout
- Fixed price agreed before we start
- Vaillant approved installer, experienced across Worcester Bosch, Ideal, Baxi, Potterton and Viessmann
- We can combine a repair visit with your annual landlord gas safety certificate if you need one
Get your hot water back today.
Gas Safe registered engineers, same-day availability across Pimlico.
Frequently Asked Questions
How fast can you reach a Pimlico combi boiler emergency?
We prioritise no-hot-water and no-heating calls and aim for same-day arrival across Pimlico. Call 020 7183 4810 for a realistic window.
Why does my combi boiler’s pressure surge when the heating comes on?
That’s usually a sign an internal component that manages pressure changes has failed. It’s a quick fix for us but not something to open the casing for yourself — call 020 7183 4810.
Is my combi boiler worth repairing or should I replace it?
It depends on its age and which part has failed. We’ll give you a straight answer on-site; if a repair genuinely isn’t good value, our Combination Boiler Installations Pimlico team can quote a replacement.
Do you carry spare parts on the van, or will I need a second visit?
Our vans carry a wide stock of genuine manufacturer parts, so most combi faults are fixed in a single visit.
Can you do my landlord gas safety certificate at the same time?
Yes — mention it when you call and we can often combine a repair with your annual CP12. See our Landlord Gas Inspection Central London service.
Book a combi boiler engineer in Pimlico
Call 020 7183 4810 or request a call-back and we’ll get your hot water and heating working properly again.
Related services: Boiler Repair Pimlico · Combination Boiler Installations Pimlico · Boiler Service London · Gas Engineer London
Peyman
CEO & Founder — Gas Safe Registered Engineer
Peyman is the founder of Olia's Plumbing & Heating, a London based team with over 15 years of hands on experience in boiler installation and repair, central heating, gas work and emergency plumbing. He personally oversees jobs across Central and West London and writes these guides to help homeowners understand their heating systems.
- Gas Safe Registered
- 15+ years experience
- Covering all of London
