Guides & advice
Know your boiler
What our engineers wish every London homeowner knew before replacing a boiler — sizing, boiler types, grants that do and don't apply, and how to tell a proper installer from a corner-cutting one.
Buying Guide · 6 min read
Are Baxi Boilers Any Good? Which Baxi Boiler Should You Choose?
Baxi boilers are a sound, budget-conscious choice when the type and output match your home. The 200 to 800 tiers mostly differ in features and warranty; sizing decides whether the boiler keeps up.
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Buying Guide · 6 min read
Are Vokera Boilers Any Good? What to Know Before Replacing Yours
Vokera is a value-to-mid-range boiler brand that does the job well when it is the right type and size and fitted properly. The bigger decision is usually what to replace an old Vokera with, not the badge on the front.
Read guideComparison · 6 min read
Which Vaillant Boiler Should I Buy? ecoFIT pure vs ecoTEC plus vs ecoTEC exclusive
Vaillant sells three tiers of gas boiler. The right one depends on your system type and hot water demand first, and budget second; the model number tells you both the type and the size.
Read guideBuying Guide · 6 min read
How Long Is a Boiler Warranty? What a New Boiler Warranty Covers
A new boiler warranty can run from a few years to over a decade. The length depends on the manufacturer, the model and the installer's accreditation, and it only holds if the boiler is registered and serviced.
Read guideHomeowner Guide · 6 min read
Can You Use the Toilet and Water While a Boiler Is Being Replaced?
Toilets and cold taps usually keep working while a boiler is replaced, because the mains is only off in short spells. Hot water and heating are off all day, and the gas for part of it.
Read guideBuying Guide · 7 min read
Can You Buy Your Own Boiler and Have It Fitted?
Buying the boiler yourself and paying someone to fit it looks like an easy saving. Sometimes it is. More often the saving shrinks once sizing, flue parts, controls and the warranty are counted.
Read guideBuying Guide · 7 min read
Small Hot Water Cylinders: What Fits a Flat or Tight Cupboard?
A small cylinder can keep stored hot water in a flat or a cramped airing cupboard. Here is what the compact, slimline and horizontal options are, what they need around them, and when to skip the cylinder altogether.
Read guideHomeowner Guide · 6 min read
Do You Need a Cylinder Thermostat With a New Boiler?
A new system or regular boiler that heats a cylinder should have a cylinder thermostat telling it when the water is hot enough. Here is what it does, why it matters at replacement, and what temperature to set.
Read guideHomeowner Guide · 6 min read
Emergency Boiler Replacement: How Fast Can a Dead Boiler Be Replaced?
Fitting a new boiler usually takes one to two days. In an emergency, the wait comes from confirming the old boiler is finished, the survey and the quote, and whether the new one can go in the same place.
Read guideBuying Guide · 5 min read
What Is a Smart Hot Water Cylinder, and Is It Worth It?
A smart cylinder adds sensors and connected controls to a normal cylinder so it can heat only the water you need and use cheaper or solar electricity. It suits some homes and is wasted money in others.
Read guideBuying Guide · 5 min read
Which Worcester Bosch Boiler Should I Choose? The Greenstar Range Explained
Worcester Bosch sells its Greenstar combis in 2000, 4000 and 8000 tiers, plus system and regular models. Pick the type and output your home needs first, then the tier your budget allows.
Read guideHomeowner Guide · 7 min read
Where Can a Boiler Flue Go? Flue Position Regulations Explained
A flue terminal can go almost anywhere on an outside wall or roof, as long as it keeps its distance from openings, eaves, corners and neighbours. On a replacement, the old position often has to change.
Read guideHomeowner Guide · 6 min read
Do You Need Planning Permission to Replace a Boiler?
Most boiler replacements need no planning permission, but every one needs Building Regulations compliance. Listed buildings, conservation-area front walls and flats are where the exceptions sit.
Read guideHomeowner Guide · 7 min read
Can You Replace a Gas Boiler in a High-Rise Flat?
Most high-rise flats with gas can have their boiler replaced, but the flue decides what is possible. Shared ducts, external access and building rules are where the extra work sits.
Read guideBuying Guide · 7 min read
What Are the Different Types of Hot Water Cylinder?
Vented, unvented, thermal store or combination unit: the type of cylinder you have decides your hot water pressure, what a replacement involves and who can fit it.
Read guideBuying Guide · 7 min read
What Are the Different Types of Boiler in the UK?
Boilers are sorted by fuel and by layout. For most London homes the real choice is between a gas combi, system or regular boiler; here is when the others come in.
Read guideHomeowner Guide · 6 min read
How Does a Boiler Work? The Parts Explained
A plain explanation of what happens inside a gas boiler, how combis and system boilers differ, and which worn parts make replacement the better answer.
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Grants & Schemes · 6 min read
Can Tenants Get a Boiler Grant? ECO4 and Renting Explained
A tenant's household can qualify for ECO4, but nothing is fitted without the landlord's permission, and a broken boiler in a rented home is the landlord's legal responsibility whatever grants exist.
Read guideHomeowner Guide · 6 min read
Boiler Cupboard Regulations: Can a New Boiler Go in a Cupboard?
A new boiler can go in a cupboard. The manufacturer's clearances decide how big the cupboard must be, and most modern room-sealed boilers need no cupboard vents.
Read guideBuying Guide · 6 min read
ErP Boiler Ratings Explained: Is Every New Boiler A-Rated?
Every new gas boiler is effectively A-rated, so the letter barely separates them. Sizing, flow temperature and the controls fitted under Boiler Plus make the real difference.
Read guideBuying Guide · 6 min read
Converting a Regular Boiler to a System Boiler: What Changes
Swapping a regular boiler for a system boiler clears some of the loft and puts the heating under pressure. Whether the cold water tank goes too depends on the cylinder you choose.
Read guideHomeowner Guide · 6 min read
Does a New Boiler Need a Bigger Gas Pipe?
A new combi can need far more gas at full rate than the boiler it replaces. Whether your existing pipe can feed it is a measurement, not a guess.
Read guideBuying Guide · 6 min read
What Size System or Regular Boiler Do I Need?
Combi sizing rules do not carry over to system and regular boilers. With a cylinder in the picture, the heat loss of the house sets the size.
Read guideHomeowner Guide · 5 min read
Do You Need to Move the Gas Meter for a New Boiler?
The meter rarely has to move when a boiler is replaced or relocated. When it does, it is a separate job arranged through your energy supplier, and it needs to happen first.
Read guideHomeowner Guide · 6 min read
Your New Boiler's Building Regulations Certificate: When It Arrives and What If It Doesn't
A new gas boiler has to be notified under Building Regulations, and you should receive a certificate by post once it is. Here is when the certificate should arrive, how to chase it and what to do if nothing turns up.
Read guideBuying Guide · 7 min read
Replacing a Back Boiler: What's Involved and Where the New Boiler Goes
A back boiler sits behind a gas fire in the fireplace, and it cannot simply be swapped for a modern one in the same spot. Here is what replacing one involves and the choices you will need to make.
Read guideBuying Guide · 6 min read
Do You Need an Immersion Heater With a New Hot Water Cylinder?
Most replacement cylinders come with an immersion heater fitted, but whether you actually use it is another matter. Here is when an immersion is a useful backup and when it becomes an expensive habit.
Read guideBuying Guide · 4 min read
How to Choose a Boiler Installer in London
A new boiler is a big-ticket, once-a-decade purchase. Here is what separates a proper installer from a corner-cutting one, before you sign anything.
Read guideComparison · 3 min read
Combi or System Boiler? Why Bathroom Count Decides It
The most common boiler question we get isn't about brands — it's combi or system. Here's how to actually decide.
Read guideGrants & Schemes · 3 min read
Does the Boiler Upgrade Scheme Pay for a New Gas Boiler?
The name is misleading for most people replacing a gas boiler. Here's what the scheme is actually for.
Read guideHomeowner Guide · 3 min read
Signs You Need a New Boiler
Not every boiler fault means replacement. Here's a genuinely useful way to think about repair versus replace.
Read guideBuying Guide · 3 min read
Combi Boiler Sizing Mistakes to Avoid
Choosing the wrong size combi boiler is a costly error; here's how to avoid the most common mistakes.
Read guideBuying Guide · 3 min read
Converting From an Oil Boiler to a Gas Boiler in London
An oil to gas boiler conversion starts with one check: does mains gas reach your property? If it does, the oil boiler and tank are safely decommissioned before the gas boiler goes in.
Read guideHomeowner Guide · 3 min read
Boiler Replacement in a Leasehold Flat: What Consent Do You Need?
If the new boiler's flue will exit anywhere different, your lease almost certainly requires written consent from the freeholder or managing agent first, because they control the external walls.
Read guideComparison · 4 min read
Unvented Cylinders: Pros and Cons for a System Boiler Replacement
An unvented cylinder is a sealed, mains-fed hot water store: strong showers and several taps at once, no loft tank. The catch is it needs good mains pressure and a qualified installer.
Read guideHomeowner Guide · 3 min read
What the Benchmark Checklist Is — and Why It Protects Your Warranty
Without a completed Benchmark checklist, a boiler manufacturer can reject your warranty claim, even if a Gas Safe engineer fitted it. Make sure you are handed a signed copy on install day.
Read guideHomeowner Guide · 3 min read
Just Bought a London Property With an Old Boiler? A First-Time Buyer's Checklist
Inherited an old boiler with your new home? Start with three checks: the model plate and manual, the service history and Benchmark log, and who last worked on it. Then plan the next step.
Read guideComparison · 3 min read
Combi vs. System Boiler: Does It Matter If Your Home Is New-Build or Period?
The age and style of your property can be the deciding factor in choosing between a combi and a system boiler.
Read guideHomeowner Guide · 4 min read
What Actually Happens on Boiler Installation Day
A clear, step-by-step walkthrough of what to expect when your new boiler is fitted, from the engineer's arrival to system handover.
Read guideHomeowner Guide · 3 min read
Does a New Boiler Need a Gas Safety Certificate? CP12 vs. Warranty
No. A brand new boiler does not come with a Gas Safety Certificate (CP12). Gas Safe Register posts you a Building Regulations Compliance Certificate once the installer notifies the job, and the installer hands you a signed Benchmark checklist. No certificate in the post? Here is how to check.
Read guideHomeowner Guide · 4 min read
Boiler Replacement for Landlords and HMO Properties in London
In an HMO, several tenants often need hot water at the same time, which a combi can struggle with. A system boiler with a cylinder usually copes better. Here is how to plan the swap around tenants.
Read guideHomeowner Guide · 4 min read
Do You Need a Power Flush Before a New Boiler?
If your radiators are cold at the bottom or the old boiler bangs and short-cycles, the system is likely full of sludge. Flushing it before the new boiler is fitted protects the boiler and its warranty.
Read guideBuying Guide · 4 min read
Is It Worth Fitting a Smart Thermostat With a New Boiler?
A smart thermostat can enhance a new boiler's efficiency, but it cannot solve fundamental heating system problems.
Read guideBuying Guide · 4 min read
Moving Your Boiler During a Kitchen Renovation or Loft Conversion
Moving your boiler during a renovation is more complex than a simple swap. Here’s why you need to plan it early and what the process involves.
Read guideHomeowner Guide · 4 min read
Why Condensate Pipes Freeze — and What It Means for a New Boiler
Condensate pipe freezing is a frequent winter problem; understanding it is key to a reliable new boiler installation.
Read guideBuying Guide · 3 min read
When Can You Skip a Power Flush With a New Boiler?
Find out if a power flush is a necessary step with your new boiler installation or an extra cost you can potentially avoid.
Read guideComparison · 4 min read
Combi vs. System Boiler for a Growing Family
Planning your family's future? Understand how your hot water needs will change and which boiler type is best for a growing household.
Read guideHomeowner Guide · 3 min read
How Long Does a New Boiler Installation Take?
A new boiler installation can take from one to two days, depending on the complexity of the job and the changes you are making.
Read guideHomeowner Guide · 4 min read
Signs Your Hot Water Cylinder Needs Replacing
Is your hot water acting up? Spot the key signs that your cylinder may be failing and needs a professional replacement.
Read guideBuying Guide · 3 min read
What Size Hot Water Cylinder Do I Need?
Allow roughly 35 to 45 litres of stored hot water per person. That puts a 1-2 bedroom, one-bathroom home at 120 to 150 litres, a 3-4 bedroom house with two bathrooms at 210 to 250 litres, and a 4+ bedroom house with three or more bathrooms at 250 to 300 litres.
Read guideHomeowner Guide · 3 min read
Can I Replace Just the Cylinder, Not the Boiler?
Often, yes. If your boiler is fairly new, runs efficiently and copes with your heating, a leaking or corroded hot water cylinder can be replaced on its own, once a survey confirms the two are compatible.
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Buying Guide · 3 min read
What Affects the Cost of a New Boiler Installation?
The price of a new boiler installation isn't fixed; several key factors determine the final cost for your London home.
Read guideHomeowner Guide · 3 min read
Moving Into a New-Build? Do You Need a Different Boiler?
If you're moving into a new-build property, you probably don't need to replace your boiler, but you should check a few key things.
Read guideHomeowner Guide · 3 min read
Boiler Installation During Winter: What to Expect
Navigating the busiest season for boiler installations in London requires planning and knowing what to expect from the process.
Read guideBuying Guide · 3 min read
How Many Radiators Can a 28kW Boiler Run? 18kW to 42kW Explained
A 28kW combi boiler typically runs around 10 to 15 radiators, a 24kW up to about 10, a 35kW roughly 12 to 16 and an 18kW system boiler around 10 to 12. The rule of thumb: 1.5kW per radiator, plus 3kW for hot water on a combi.
Read guideComparison · 3 min read
Combi Boiler vs. Electric Boiler for London Flats
If your flat has mains gas and a flue route, a gas combi is usually the cheaper boiler to run, because electricity costs more per unit of heat. If there is no gas supply, or a flue is impractical, an electric boiler is the practical answer.
Read guideHomeowner Guide · 4 min read
Does a New Boiler Increase Your Rental Property's Appeal?
A modern, reliable boiler is a key factor in attracting and retaining good tenants for your rental property.
Read guideHomeowner Guide · 3 min read
What to Do If Your Installer Recommends a Bigger Boiler Than Expected
Discover the legitimate reasons an installer might suggest a larger boiler and the steps you can take to verify their recommendation.
Read guideComparison · 4 min read
Heat Pump vs Gas Boiler: Which Is Right for a London Home?
Choosing between a heat pump and a gas boiler depends on your London home's setup, insulation, and heating needs.
Read guideBuying Guide · 5 min read
What a Hot Water Cylinder Replacement Costs in London
Hot water cylinder replacement cost depends on which of three jobs you need: a vented swap, an unvented swap, or converting vented to unvented. Here is what separates them on price.
Read guideHomeowner Guide · 5 min read
When to Replace a Hot Water Cylinder Rather Than Repair
Not every cylinder fault is a replacement, and not every working cylinder is worth keeping. The decision turns on which component has actually failed.
Read guideBuying Guide · 5 min read
How to Check Your Cylinder Installer Is G3 Qualified
A Gas Safe number tells you nothing about whether someone may legally fit your unvented cylinder. Here is what to ask for, and how to check it.
Read guideComparison · 5 min read
Unvented or Vented? Choosing a Replacement Cylinder
When the old cylinder goes, you get one cheap opportunity to change system type. Whether you should take it comes down to your mains supply.
Read guideBuying Guide · 7 min read
What Is a Combi Boiler? How It Works and Who It Suits
One box on the wall, no cylinder, no loft tank. Here is how a combi boiler actually works, where it shines and where it runs out of road.
Read guideBuying Guide · 7 min read
Comparing Boiler Quotes: What Each One Should Include
Three boiler quotes for the same house can be thousands apart. Usually they are not quoting for the same job. Here is how to line them up.
Read guideBuying Guide · 7 min read
Changing to a Combi Boiler: Cost Factors and What's Involved
Swapping a boiler, cylinder and loft tanks for one combi is a bigger job than a straight replacement. Here is what the work involves and what drives the price.
Read guideComparison · 6 min read
Condensing Boiler vs Combi Boiler: What's the Difference?
People ask whether to get a condensing boiler or a combi. The honest answer is that almost every new combi is a condensing boiler. Here is why.
Read guideHomeowner Guide · 7 min read
How Long Do Boilers Last? Lifespan and When to Replace
Ten to fifteen years is the usual answer, but two boilers of the same age can be in very different shape. Here is what decides how long yours lasts.
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