Author: Gio Nera Marketing

Combi Boiler: No Hot Water but Heating Works? Causes and Fixes

Posted on July 20, 2026 by Gio Nera Marketing - Boiler Repair

If your combi boiler has stopped producing hot water, it’s frustrating — but the cause is often something simple you can check yourself. This guide covers why a combi boiler has no hot water, including the common situation where the heating works but there’s no hot water, and how to fix it.

First, check these quick things

Check the boiler pressure. Look at the gauge — it should read around 1 to 1.5 bar. If it’s below 1 bar, low pressure can stop the boiler heating water. Top it up using the filling loop, or see our guide on boiler pressure.
Check the thermostat and controls. Make sure the hot water setting hasn’t been turned down or a timer isn’t switching it off.
Check other taps. If only one tap has no hot water, the problem is that tap or its cartridge, not the boiler.
Reset the boiler. If there’s a fault code on the display, note it down and try the reset button once.

No hot water but the heating still works?

This is one of the most common combi boiler faults, and it usually points to one thing: a stuck diverter valve. The diverter valve switches the flow of hot water between your radiators and your taps. When it sticks in the heating position, your radiators stay warm but no hot water reaches the taps. A diverter valve is an internal component that needs a Gas Safe registered engineer to repair or replace — it’s not a DIY job.

Other causes of no hot water

Low boiler pressure: the most common and easily fixed cause.
A faulty diverter valve: the usual culprit when heating works but hot water doesn’t.
An airlock: trapped air in the pipework can block the flow of water.
A broken thermostat or PCB: the boiler’s controls can fail and stop it firing for hot water.
A frozen condensate pipe: in very cold weather, a frozen pipe can cause the boiler to shut down.

Is it worth repairing?

Most no-hot-water faults — a diverter valve, thermostat, or pressure issue — are straightforward, affordable repairs and well worth fixing. If your boiler is over ten years old and faults are becoming frequent, an engineer can advise whether a repair or a new boiler makes more financial sense.

When to call a professional

Checking the pressure and controls is safe to do yourself. But a diverter valve, PCB, thermostat, or airlock should be handled by a Gas Safe registered engineer. If you’ve checked the pressure and controls and still have no hot water, it’s time to book a boiler repair. It’s also worth checking your radiators are heating up correctly, as related faults can affect both.

Frequently asked questions

Why does my combi boiler have heating but no hot water?

This is almost always a stuck or faulty diverter valve, which controls whether hot water goes to your radiators or your taps. It needs a Gas Safe engineer to fix.

Can low boiler pressure cause no hot water?

Yes. If pressure drops below 1 bar, the boiler may stop heating water. Top it up to around 1 to 1.5 bar and see if hot water returns.

Should I reset my boiler if there’s no hot water?

You can try the reset button once if there’s a fault code. If it doesn’t restore hot water or the fault returns, call an engineer rather than repeatedly resetting.

Need a boiler engineer in West London?

If you’ve run the checks above and still have no hot water, our engineers can diagnose and fix it fast. Our Gas Safe registered engineers provide fast, reliable boiler repairs and plumbing and heating services across West London, often fixing the problem in a single visit.

Tel: 020 3561 4415

Boiler Leaking Water? Common Causes and What to Do

Posted on July 20, 2026 by Gio Nera Marketing - Boiler Repair

A boiler leaking water should never be ignored. Water and electricity are a dangerous combination, and even a small leak can corrode components, damage your home, and lead to a complete breakdown if left unchecked. This guide explains the most common reasons a boiler leaks water and exactly what you should do.

What to do first if your boiler is leaking

If you can see water leaking from your boiler, take these steps before anything else:

Turn the boiler off at the mains and switch off the central heating.
Turn off the water supply to the boiler using the internal stop tap if the leak is significant.
Mop up standing water and place a container under the leak to protect your flooring.
Do not try to open up the boiler. The inside of a boiler should only ever be worked on by a Gas Safe registered engineer.

Common causes of a boiler leaking water

High boiler pressure: if the pressure is too high, the pressure relief valve opens to let water out, often through a pipe outside. Check the gauge — if it’s in the red, see our guide on boiler pressure that’s too high.
A faulty pressure relief valve: the valve itself can wear out and let water escape even at normal pressure.
Corroded pipes or heat exchanger: over time, internal parts corrode. A leaking heat exchanger is a serious fault and usually means a repair or replacement by an engineer.
Worn pump seals: the seals around the circulating pump degrade with age and can drip.
Loose joints and connections: pipe fittings can loosen over time, particularly after recent work on the system.

Where is the water coming from?

The location of the leak is a useful clue. Water dripping from a pipe outside the property usually points to high pressure or a faulty pressure relief valve. Water pooling underneath the boiler often indicates a failed seal, corroded pipe, or heat exchanger fault. Either way, the internal cause needs a professional diagnosis.

Is a leaking boiler dangerous?

A leaking boiler isn’t usually an immediate danger, but it shouldn’t be left. Water can reach electrical components and cause a short, corrosion accelerates once it starts, and a leak can quickly turn a small repair into a full breakdown. If you ever smell gas as well as seeing a leak, turn off the gas at the meter and call the National Gas Emergency line on 0800 111 999 immediately.

When to call a professional

Almost all boiler leaks need a Gas Safe registered engineer. The one exception is high pressure, which you can often reduce yourself by bleeding a radiator — but if the pressure keeps climbing or water keeps leaking, the underlying fault still needs fixing. Never attempt internal boiler repairs yourself.

Frequently asked questions

Can I still use my boiler if it’s leaking?

No. Turn it off and avoid using it until an engineer has inspected it. Running a leaking boiler risks electrical faults and further damage.

Why is my boiler leaking water from underneath?

A leak underneath usually points to a failed internal seal, a corroded pipe, or a heat exchanger fault — all of which need a Gas Safe engineer.

Why is water coming from the pipe outside my house?

That’s the pressure relief valve discharge pipe. It releases water when boiler pressure is too high or the valve is faulty. Check the pressure gauge first.

Need a boiler engineer in West London?

If your boiler is leaking, don’t wait for it to become a full breakdown. Our Gas Safe registered engineers provide fast, reliable boiler repairs and plumbing and heating services across West London, often fixing the problem in a single visit.

Tel: 020 3561 4415

Radiator Not Heating Up? Common Causes and How to Fix It

Posted on July 8, 2026 by Gio Nera Marketing - Boiler Maintenance

A radiator that won’t heat up is one of the most common heating complaints, and the good news is that the cause is usually easy to identify. Where the radiator is cold tells you a lot about what’s wrong. This guide runs through the most common reasons a radiator isn’t heating up and how to fix each one.

Start by checking where the radiator is cold

Before anything else, feel the radiator while the heating is on. Where it’s cold points straight to the likely cause:

Cold at the top, warm at the bottom: trapped air
Cold at the bottom, warm at the top: sludge build-up
Cold all over (but others are warm): a stuck valve or closed valve
Every radiator cold: a boiler, pump or system-wide issue

1. Trapped air (cold at the top)

If the radiator is warm at the bottom but cold at the top, air is trapped inside and stopping hot water from reaching the top. This is the easiest fix — you simply bleed the radiator to release the air. Follow our step-by-step guide on how to bleed a radiator, then check your boiler pressure afterwards and top it up if needed.

2. A stuck thermostatic radiator valve (TRV)

Each radiator usually has a thermostatic valve (the numbered dial). Over the summer, when the heating is off, the pin inside can stick in the closed position, so the radiator stays cold even when turned up. To check, unscrew the TRV head and look at the small pin underneath — gently moving it up and down with pliers will often free it. If the radiator warms up afterwards, that was the culprit.

3. Sludge build-up (cold at the bottom)

If the radiator is warm at the top but cold at the bottom, the problem is usually a build-up of sludge — rust and debris (magnetite) that settles at the base and blocks the flow of hot water. Bleeding won’t fix this. The system needs a chemical flush or a power flush, which is a job for a professional. Left untreated, sludge reduces the efficiency of your whole system and can damage the boiler and pump.

4. Closed or unbalanced valves

Check that both valves on the radiator are fully open — the TRV at one end and the lockshield valve (usually under a plastic cap) at the other. If a single radiator furthest from the boiler struggles to heat while those nearest run hot, your system may need balancing, which involves adjusting the lockshield valves so hot water is distributed evenly. A heating engineer can balance the system quickly.

5. A boiler or pump problem (all radiators cold)

If none of your radiators are heating up, the issue is more likely with the boiler or circulating pump than the radiators themselves. First, check the boiler is firing and that the pressure gauge reads around 1 to 1.5 bar — if it’s low, top it up, and if it’s high, see our guide on boiler pressure that’s too high. If the boiler is working but the radiators stay cold, the pump may have failed or seized, which needs a Gas Safe registered engineer.

When to call a professional

Bleeding a radiator and freeing a stuck TRV pin are safe DIY jobs. Call a heating engineer if the water from the radiators is dark and dirty (sludge), if radiators need balancing, if the pump has failed, or if no radiators are heating at all. Our heating team can diagnose and fix the problem, and flush the system if needed, to get your heating running efficiently again.

Frequently asked questions

Why is only one radiator not heating up?

A single cold radiator usually points to trapped air, a stuck TRV, or a closed valve on that radiator. Feel where it’s cold to narrow it down — cold at the top means air, cold at the bottom means sludge.

Why are all my radiators cold but the boiler is on?

This usually indicates a circulation problem, such as a failed pump or a system-wide airlock, rather than a fault with the radiators. It’s best checked by an engineer.

Can I fix a radiator that won’t heat up myself?

Often, yes. Bleeding the radiator or freeing a stuck TRV pin can be done safely at home. Sludge removal, balancing and pump faults should be left to a professional.

Need help with your heating in West London?

If your radiator still won’t heat up after these checks, it’s worth having a professional take a look before the problem spreads to the rest of your system. Our Gas Safe registered engineers provide fast plumbing and heating services across West London, including radiator balancing, power flushing and boiler repairs.

Tel: 020 3561 4415

Boiler Pressure Too High? Causes and How to Fix It

Posted on July 7, 2026 by Gio Nera Marketing - Boiler Repair

Most boilers run at a pressure of around 1 to 1.5 bar. If the needle on your pressure gauge has climbed into the red zone — usually above 2.75 bar — your boiler pressure is too high. It’s a common problem, it’s rarely dangerous thanks to built-in safety valves, and in many cases you can bring it back down yourself. Here’s what causes high boiler pressure and how to fix it.

What is normal boiler pressure?

A healthy combi boiler sits at roughly 1 to 1.5 bar when the heating is off and cold. When the heating is running, it’s normal for the pressure to rise to around 2 bar — that’s nothing to worry about. It’s only a concern when the pressure stays high, or climbs towards 3 bar and into the red section of the gauge.

What causes high boiler pressure?

Overfilling during a top-up: the most common cause. If too much water is added through the filling loop, or the filling loop valves are left slightly open, pressure builds up.
A faulty expansion vessel: this part absorbs the expansion of hot water. If it loses its charge, the pressure has nowhere to go and rises sharply when the heating is on.
A faulty pressure relief valve: the safety valve that releases excess pressure can stick or fail over time.

Is high boiler pressure dangerous?

In almost all cases, no. Every modern boiler has a pressure relief valve designed to release excess pressure safely — you may notice water leaking from your boiler or dripping from a small pipe outside your home, which is the valve doing its job. That said, high pressure shouldn’t be ignored, as it puts strain on the system and points to a fault that will keep coming back until it’s fixed.

How to reduce boiler pressure yourself

Bleeding a radiator is one of the safest ways to bring the pressure down, and it can also help if you have a radiator that won’t heat up. Work through these steps:

Check the filling loop is fully closed. This is the flexible braided hose beneath the boiler. If either valve is even slightly open, close it fully — this alone often solves the problem.
Bleed a radiator. Releasing a little water from a radiator lowers the pressure in the system. Our guide on how to bleed a radiator walks you through it. Keep an eye on the gauge as you go and stop once it returns to around 1.5 bar.
Re-check the gauge. With the heating cold, the needle should now sit between 1 and 1.5 bar.

When to call a Gas Safe engineer

If the pressure keeps rising after you’ve closed the filling loop and bled a radiator, the cause is likely a faulty expansion vessel or pressure relief valve. These are sealed parts of the boiler and should only be repaired or replaced by a Gas Safe registered engineer — never attempt to work on internal gas components yourself. You should also call an engineer if water leaks continuously from the outside overflow pipe, or if the boiler locks out and won’t fire.

Our Gas Safe registered team offers fast boiler repairs across West London and can diagnose and fix a pressure fault, usually in a single visit.

Frequently asked questions

What pressure should my boiler be at?

Around 1 to 1.5 bar when the heating is cold. It’s normal for it to rise to about 2 bar while the heating is running.

Can I use my boiler if the pressure is too high?

It will usually keep working, and the pressure relief valve protects it, but you should bring the pressure down and have any underlying fault checked to avoid repeated problems.

Why does my boiler pressure keep rising?

If it climbs again after being reset, the most likely causes are a filling loop that isn’t fully closed or a faulty expansion vessel. The expansion vessel needs a Gas Safe engineer to re-pressurise or replace.

Need help with your heating in West London?

If your radiators or boiler still aren’t behaving after trying the steps above, our Gas Safe registered engineers can help. We provide fast, reliable plumbing and heating services across West London, from radiator and boiler repairs to full system checks.

Tel: 020 3561 4415

How to Bleed a Radiator: A Simple Step-by-Step Guide

Posted on July 7, 2026 by Gio Nera Marketing - Boiler Maintenance

If one or more of your radiators are cold at the top but warm at the bottom, trapped air is usually to blame. Bleeding your radiators releases that air so hot water can circulate properly again — and it’s one of the simplest bits of home heating maintenance you can do yourself. This guide walks you through how to bleed a radiator safely, step by step.

What does bleeding a radiator do?

Over time, air becomes trapped inside your central heating system. Because air rises, it collects at the top of your radiators and stops hot water from filling that section. The result is a radiator that’s warm at the bottom and cold at the top, meaning your heating works harder, your rooms take longer to warm up, and your energy bills creep up. Bleeding simply lets that trapped air escape.

Signs your radiators need bleeding

The radiator is cold at the top but warm at the bottom
Rooms take a long time to heat up
You hear gurgling or rattling noises from the radiators
Some radiators stay cold while others get hot
Damp or mould appearing because rooms aren’t heating evenly

What you’ll need

A radiator bleed key (available cheaply from any DIY shop) or a flat-head screwdriver for newer valves
A cloth or old towel
A small container to catch drips

How to bleed a radiator: step by step

Turn your heating on fully so the system reaches pressure and you can feel which radiators have cold spots.
Turn the heating off and let the radiators cool. Never bleed a hot radiator — you risk scalding yourself with hot water.
Find the bleed valve at the top corner of the radiator. Hold your cloth underneath and fit the bleed key onto the square valve.
Turn the key slowly anti-clockwise, about a quarter to half a turn. You’ll hear a hissing sound as the trapped air escapes.
Wait for the hiss to stop. When a steady trickle of water comes out instead of air, the radiator is fully bled.
Close the valve by turning the key clockwise. Don’t overtighten it — snug is enough.
Repeat for each radiator, working from the ground floor up, then the upstairs radiators.

Check your boiler pressure afterwards

Bleeding radiators releases water as well as air, which can lower the pressure in your system. Once you’ve finished, check the pressure gauge on your boiler — it should sit at around 1 to 1.5 bar when the heating is cold. If it has dropped below 1 bar, you’ll need to top it up using the filling loop. If instead you find your boiler pressure is too high, we cover the causes and fixes in a separate guide.

How often should you bleed your radiators?

For most homes, bleeding your radiators once a year — ideally at the start of autumn before you rely on the heating — is enough. If you notice cold spots returning quickly after bleeding, it can point to a bigger issue such as a build-up of sludge or a circulation problem, which is worth having a professional look at.

When to call a professional

Bleeding radiators is a safe DIY job, but call a heating engineer if radiators stay cold after bleeding, if you keep having to bleed the same radiator, if the water that comes out is very dark or dirty (a sign of sludge), or if you spot leaks around the valves. Our plumbing and heating team can flush the system, balance your radiators, and get your heating running efficiently again.

Frequently asked questions

Should the heating be on or off when bleeding a radiator?

Turn the heating off and let the radiators cool before bleeding them. Bleeding a hot radiator can spray out scalding water.

Do I need to bleed radiators upstairs or downstairs first?

Start with the downstairs radiators, then move upstairs. On each floor, begin with the radiator furthest from the boiler.

Why is my radiator still cold after bleeding?

If a radiator is cold at the bottom rather than the top, the problem is usually sludge build-up rather than air, and the system may need a power flush. If it’s cold all over, check the valves are open. Persistent cold radiators are worth a professional inspection — see our full guide on why a radiator is not heating up.

Need help with your heating in West London?

Tel: 020 3561 4415

The Seven Benefits of Having an Annual Boiler Service

Posted on January 10, 2024 by Gio Nera Marketing - Uncategorised

For homeowners in Chiswick and the surrounding areas, ensuring the optimal functioning of your boiler is crucial, especially during the colder months. West London Plumbing Ltd highlights the seven key benefits of having an annual boiler service in Chiswick. Regular maintenance not only enhances the performance of your gas boiler but also ensures safety and efficiency.

1. Increased Safety

Preventing Gas Leaks: Regular servicing can detect and fix any potential gas leaks, ensuring the safety of your home.
Carbon Monoxide Detection: A service checks for carbon monoxide leaks, protecting you from this silent killer.

2. Improved Efficiency

Optimal Performance: Servicing ensures your boiler operates at its maximum efficiency, saving you money on energy bills.
Fuel Economy: An efficient boiler uses less fuel, reducing your carbon footprint and energy costs.

3. Extended Boiler Lifespan

Preventive Care: Regular maintenance can extend the lifespan of your boiler, ensuring it lasts as long as possible.
Early Problem Detection: Servicing can catch issues early, preventing costly repairs or replacements.

4. Reduced Risk of Breakdowns

Minimising Emergencies: Annual services reduce the likelihood of unexpected breakdowns, especially during winter.
Reliability: A well-maintained boiler is more reliable, providing consistent warmth when you need it.

5. Maintaining Warranty Coverage

Warranty Requirements: Many boiler warranties require annual servicing to remain valid.
Service Records: Keeping up with annual services provides a record of maintenance, which is often needed for warranty claims.

6. Legal Compliance for Landlords

Safety Certificates: Landlords are legally required to have gas boilers serviced annually and obtain Gas Safety Certificates.
Tenant Safety: Regular servicing ensures the safety of tenants and compliance with legal obligations.

7. Peace of Mind

Assurance: Knowing your boiler is in good condition offers peace of mind.
Preparedness for Winter: A serviced boiler is less likely to fail in the cold months, ensuring you stay warm and comfortable.

West London Plumbing Ltd: Your Local Boiler Service Experts

Residents in Brentford, Chiswick, Ealing, Hammersmith, and across West London can trust West London Plumbing Ltd for reliable and comprehensive boiler services. Our team of experienced professionals offers top-quality boiler service in Chiswick, ensuring your heating system is efficient, safe, and ready to handle your heating needs. Contact us for professional boiler maintenance and enjoy the benefits of a well-serviced heating system in your home.

Author: West London Plumbing Ltd

Addressing Boiler Pressure Loss: A Practical Guide

Posted on January 3, 2024 by Gio Nera Marketing - Uncategorised

Experiencing a loss of pressure in your gas boiler can be a cause for concern. At West London Plumbing Ltd, specialists in boiler repairs in Brentford, we often encounter this issue. Understanding the reasons behind pressure loss and knowing how to respond can be crucial for maintaining your boiler’s efficiency and longevity.

Identifying the Causes of Pressure Loss

A drop in boiler pressure can be attributed to several factors:

Leaks in the System: The most common cause of pressure loss is a leak somewhere in the heating system. This could be in the pipes, radiators, or the boiler itself.
Recently Bled Radiators: If you’ve recently bled your radiators to release trapped air, this can sometimes result in a drop in pressure.
Faulty Components: Faults in components such as the pressure relief valve or the expansion vessel can lead to pressure issues.

Steps to Re-Pressurise Your Boiler

If you notice your boiler’s pressure gauge showing a drop, here are steps you can take:

Locate the Filling Loop: This is usually a silver or grey hose with a valve at each end, connected to your boiler.
Check the Boiler Manual: Before proceeding, consult your boiler’s manual for specific instructions on re-pressurising your model.
Turn Off the Boiler: Ensure the system is cool before you start.
Open the Valves: Slowly open both valves to allow cold water into the system. You will hear water flowing into the boiler.
Monitor the Pressure Gauge: Watch the pressure gauge, and once it reaches around 1.5 bar, close both valves.
Restart the Boiler: Turn your boiler back on and check if it operates normally.

When to Call a Professional

If you’re unable to re-pressurise your boiler, or if the pressure drops again shortly after re-pressurising, it’s time to call a professional. Persistent pressure issues could indicate a more serious underlying problem that requires expert attention.

Regular Maintenance: The Key to Preventing Pressure Issues

Regular boiler servicing can help prevent pressure problems. A qualified engineer can identify and fix any potential issues before they cause a breakdown.

West London Plumbing Ltd: Your Local Boiler Experts

For residents in Brentford, Chiswick, and the surrounding areas, West London Plumbing Ltd is your reliable partner for all boiler-related issues. Whether it’s re-pressurising your boiler, regular servicing, or more complex repairs, our team of experienced professionals is here to provide swift and efficient solutions. Contact us for all your boiler needs, and rest assured of a warm, comfortable home.