Heating guides
The questions people ask us on the phone before they are ready to book anything — answered properly, without a sales pitch attached.
Boiler breakdowns and servicing
Most boiler problems show up as a symptom first: no hot water, cold radiators or pressure that keeps dropping. These guides explain what a symptom usually points to, what you can safely check yourself, such as the pressure gauge or the thermostat, and when the boiler needs a Gas Safe registered engineer.
Low boiler pressure: what the gauge means and how to fix it
The most common reason a boiler stops in a London home, the easiest thing to fix, and the one most often fixed the wrong way.
Read the guideYour boiler has stopped: what to check before you call an engineer
Seven checks, in order, that between them account for a large share of the calls we take on a cold evening.
Read the guideGetting a London home's heating ready for winter
Every year the first hard frost produces more breakdown calls in three days than the whole of the summer. Almost none of them are a surprise.
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Boiler flue regulations: flue position, ceiling voids and sign-off in England
What boiler flue regulations in England cover: regulation 27, Approved Document J, flues in ceiling voids and who signs the work off.
Read the guideCompliance certificate for a boiler: which document you need in England
The compliance certificate for a boiler is a Building Regulations certificate. See who issues it, when it arrives and what to do if it is missing.
Read the guideBoiler certificates: which ones expire and which need renewing each year
Which boiler certificate expires and which does not: the 12-month gas safety rule, early renewal and the one-off building regs certificate.
Read the guideHot water cylinder banging or vibrating when a tap is opened: water hammer or moving pipework?
A bang as a tap opens is water hammer; a hum while water runs is moving pipework. Learn how to tell them apart and who may fix each.
Read the guideBoiler pressure too high: the three usual causes and what you can check
Boiler pressure too high? What a reading above the marked range means, the three usual causes, and which checks need a Gas Safe engineer.
Read the guideBoiler low pressure: what the gauge is telling you
Boiler low pressure explained: normal bar readings, why pressure drops, what you may check safely and when to call a Gas Safe engineer.
Read the guideWhy the expansion vessel on your unvented cylinder loses its charge
Why an unvented cylinder expansion vessel loses its charge, what water at the tundish means, and who is allowed to recharge it.
Read the guideFrozen condensate pipe: how to spot it and thaw it safely
How to tell if your boiler's condensate pipe has frozen, how manufacturers say to thaw it safely, and when to call a Gas Safe engineer.
Read the guideVaillant fault codes explained: F75, F28, F22 and F62
What Vaillant fault codes F75, F22, F28 and F62 mean, what you can safely check yourself and when a Gas Safe engineer is needed.
Read the guideDo you need a boiler service record or gas safety certificate to sell a house in England?
No law in England requires a boiler service certificate to sell your home. Here is what buyers' solicitors actually ask for.
Read the guideHow often should a boiler be serviced?
How often a boiler should be serviced in England: annual servicing, landlord duties under GSIUR 1998 and what warranties require.
Read the guideWhat does a boiler service include?
What a Gas Safe engineer checks at an annual boiler service, what you receive afterwards, and how it differs from a safety check.
Read the guideHot water works but the radiators stay cold
Hot water works but radiators stay cold? Find the likely cause, what you can safely check, and when a Gas Safe engineer is needed.
Read the guideRepair or replace: deciding about an ageing boiler
Repair or replace your boiler? Judge it by age, spare parts, breakdown frequency, efficiency band and safety findings.
Read the guideNo hot water but the heating still works
Radiators hot but the taps run cold? What causes it on combi and cylinder systems, what you can check safely, and when a Gas Safe engineer is needed.
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Landlord gas safety
Landlords must have the gas appliances and flues they provide safety-checked at least every 12 months by a Gas Safe registered engineer, keep the pipework and fittings in a safe condition, and give tenants a copy of the record. These guides answer the questions that come up around that check, from HMOs and empty periods between tenancies to how the check differs from a boiler service.
Heating in every room: what a landlord must provide in England
Does a landlord have to provide heating in every room? What English law requires, which appliances count, and what to do if it fails.
Read the guideCP12 in London flats: communal boilers, shared flues and borough HMO rules
What a CP12 covers in a London flat or HMO: communal boilers, flues in ceiling voids, borough licence conditions and subletting.
Read the guideCapping off a let property's gas supply when there are no gas appliances
With no gas appliances, the annual check falls away. Who may cap the supply at the meter, and which landlord duties carry on.
Read the guideWhen should a landlord replace a boiler instead of repairing it again?
Repair again or replace? The duties, repeat failures and spare parts signals that tell a landlord in England when a let property needs a new boiler.
Read the guideGas safety certificate with no gas appliances: the pipework duty that remains
No gas appliances in a rented home? No annual gas safety check is due in England, but the pipework still has to be kept safe.
Read the guideGas safety certificate for a lodger: yes, renting a room makes you a landlord
Taking in a lodger makes you a landlord under gas law in England. What the annual check covers, who gets a copy and how long to keep it.
Read the guideGas safety in a leasehold flat: who is responsible for the check
Gas safety in a leasehold flat: when the freeholder, the leaseholder or a sub-letting owner carries the duty, and what the lease decides.
Read the guideBuying a house with no boiler building regs certificate: what to ask before exchange
What to ask the seller when a boiler has no building regulations certificate, who can apply for regularisation, and which papers matter.
Read the guideGas safety certificate: how to check it is genuine and the engineer is registered
Check the engineer's ID card, the registration number and the six details every gas safety record must show in England.
Read the guideBoiler certificate with wrong details: check these fields before you file it away
Check the address, date, engineer number and appliances on your gas safety record the day it arrives — and how to get a wrong one corrected.
Read the guideBoiler not notified to building control: the regularisation route in England
A boiler replacement never notified in England: how the regularisation route works, who applies to the council and what the certificate proves.
Read the guideBuying a tenanted property with no gas safety record: the paperwork you inherit
Completion makes you the landlord for gas safety in England. What paperwork you should get from the seller, and what to arrange if it is missing.
Read the guideLetting agents and landlords: who actually carries the gas safety duty?
The landlord keeps the gas safety duty in England unless the management contract clearly gives it to the agent. What HSE expects and what to check.
Read the guideGas safety records and section 21 notices in England
Section 21 ended in England on 1 May 2026. How an invalid gas safety record blocked a notice, and what landlords must do now.
Read the guideDo I have to give my tenant the gas safety certificate? Deadlines and records
Yes — in England you must give existing tenants a copy of the gas safety record within 28 days, and new tenants before they move in.
Read the guideDomestic or non-domestic for gas safety: how to work out which rules apply
Domestic or commercial for gas safety? How the test works part by part — flat above a shop, converted offices, shared blocks.
Read the guideImmediately Dangerous and At Risk: why an appliance fails a gas safety check
Immediately Dangerous and At Risk explained: what each gas safety classification means for a landlord, and what you can arrange next.
Read the guideDoes a new boiler need a new landlord gas safety certificate?
A new boiler in a rented home needs its first gas safety check within 12 months of installation. What the law in England requires.
Read the guideCarbon monoxide alarm rules for rented homes in England
Where a carbon monoxide alarm is required in a rented home in England, who tests it and what happens if you do not fit one.
Read the guidePenalty for no gas safety certificate: who enforces the landlord duty in England
No valid gas safety certificate in England? See who enforces the landlord duty, what HSE can do and what it means for your tenancy.
Read the guideLandlord gas safety certificate renewal: the 12-month rule, early renewal and lapsed records
There is no grace period once a landlord gas safety record expires. Learn the 12-month rule and the two-month early renewal window.
Read the guideWhich appliances, pipework and flues appear on a gas safety record
Does a gas cooker belong on the CP12? What appliances, flues and pipework a landlord gas safety record must list in England.
Read the guideNew gas safety certificate between tenants? What applies to an empty property
A new tenancy does not reset the 12-month cycle. When the existing gas safety record still covers your property, and when to check again.
Read the guideGas safety check or boiler service: what is the difference?
A gas safety check proves an appliance is safe; a service keeps it working. What each covers, who needs which, and what the law says.
Read the guideGas safety in an HMO: what changes for you
What an HMO gas safety certificate requires in England: the annual check, the council's 7-day request, communal boilers, bedsits and CO alarms.
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Landlord Gas Safety Certificate (CP12): what the job involves
Radiators and system health
Sludge and debris in a heating system show up as radiators that stay cold at the bottom, noisy pipes or a boiler that works harder than it should. These guides explain what those signs mean and when cleaning the system, for example with a power flush, actually helps.
Power plumbing: power flushing, sludge and what a clean system changes
Power plumbing usually means power flushing: a pumped clean of your central heating. What it fixes, when you need it and who may do the work.
Read the guideShower goes cold when a tap is used, or hot when the toilet flushes
Shower goes cold when a hot tap runs, or scalding when the toilet flushes? Learn which cause fits your home and what an engineer checks.
Read the guideRadiator cold at the top and warm at the bottom: what it is telling you
Radiator cold at the top and warm at the bottom usually means trapped air, not sludge. What you can check, and when to call an engineer.
Read the guideIs a magnetic filter worth it on a central heating system?
What a central heating magnetic filter catches, where it is fitted, how often it needs cleaning and how it affects boiler guarantees.
Read the guideDo you need a power flush with a new boiler?
No manufacturer demands a power flush — warranties need a system cleaned and inhibited to BS 7593. When flushing matters before a new boiler.
Read the guideRadiator hot at the top and cold at the bottom: what it means
Radiator cold at the bottom but hot at the top usually means sludge. Learn how to tell it apart from trapped air and what fixes it.
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Replacing a boiler
Replacing a boiler raises more questions than the choice of model: whether the old one is still worth repairing, whether a combi can keep up with two bathrooms, and whether the radiators have to go too. These guides work through those decisions before a survey.
Combi, system or regular boiler: which suits a London home?
Three types of boiler, one decision, and it is settled by two numbers most quotes never mention.
Read the guideRemoving a back boiler: what is actually involved
Thousands of London houses still heat themselves from a boiler hidden behind the living room fireplace. Replacing one is not a swap.
Read the guideSystem to combi conversion: what you gain, what you lose
Removing the cylinder and the loft tanks frees up real space in a London house. It also removes something, and the something is worth understanding first.
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How far a boiler can be from an outside wall: the flue length sets the limit
No fixed distance applies: the boiler's maximum flue length, minus what each bend costs, decides how far inside it can sit.
Read the guideBoiler position regulations: where a new boiler is allowed to go
Which rooms a boiler may go in, how the flue, condensate and clearances limit the position, and what moving it adds to the job.
Read the guideNew boiler and EPC rating: what it changes when you sell your home
A new boiler is one input in your EPC, not the whole score. What the assessor records, when you need a fresh EPC and which papers buyers ask for.
Read the guideBoiler flue under a carport or balcony: when each position is allowed
Where a boiler flue may not terminate — carport, balcony, side return, deep eaves — and when a terminal guard is needed.
Read the guideNeighbour's boiler flue pointing at your house: clearances, plume and who to contact
A neighbour's flue aimed at your house: boundary clearances, what the white plume is, and the council and gas safety routes you can use.
Read the guideBoiler flue in a ceiling void: why an inspection hatch is asked for
What a concealed flue in a ceiling or wall void means, why Approved Document J asks for inspection hatches, and what At Risk means.
Read the guideWater coming out of the vent pipe into a loft tank: what it means and what you can check
Water discharging from the vent pipe into a loft tank signals a system fault. What it means, what is legal in England, what you can check.
Read the guideCombi boiler hot water goes hot then cold: the cold water sandwich explained
Why combi hot water runs hot, then cold, then hot again: flow rate, pre-heat, diverter valve, and the four checks you can safely make.
Read the guideNew flue with a new boiler: when it is needed and why
A new boiler usually comes with a new flue: what regulation 27 requires in England, when the old opening can be reused, and what the survey checks.
Read the guideReplacement boiler installation certificate: the three documents you should end up with
A replacement boiler in England means three documents, not one: the compliance certificate, the Benchmark checklist and the warranty.
Read the guideFreeholder permission to replace a boiler: what your lease decides
When a leaseholder needs freeholder consent for a new boiler in England, what the lease controls and how building regulations differ.
Read the guideNew boiler installation certificate: which document you actually get
Which certificate you get after a new boiler in England, who issues it, the legal deadlines, and what to do if it never arrived.
Read the guideThe building regulations compliance certificate after a new boiler
What the building regulations compliance certificate for a new boiler covers in England, who issues it, when it arrives and what to keep.
Read the guideReplacing a back boiler: what the work involves and what the rules say
Replacing a back boiler in England: the safety risk of leaving it, your boiler options, Boiler Plus rules and sign-off.
Read the guideAfter an extension or loft conversion: will your boiler still cope?
Boiler not big enough after an extension? How to spot it, what a heat loss calculation covers and which rules apply in England.
Read the guideBoiler flue regulations and planning in conservation areas and listed buildings
Boiler flue regulations in England: gas safety law, Approved Document J and clearances, and when a conservation area needs planning permission.
Read the guideBoiler flue distances from windows, and flue options in flats and terraced houses
How far a boiler flue must sit from a window, plus plume kits, vertical and twin flue options for flats and terraced houses.
Read the guidePutting a boiler in the loft: access, frost and what the rules require
What the rules in England require for a loft boiler: notification, flue inspection access, safe loft access and frost protection that works.
Read the guideWill gas boilers be banned in the UK?
No ban on existing gas boilers. What the 2026 building regulations mean for new homes in England, with the official dates.
Read the guideWhat happens during a free boiler survey
What a boiler survey covers: the checks a Gas Safe engineer makes, the measurements taken and what to have ready before the visit.
Read the guideDo your radiators need replacing when the boiler does?
No, a new boiler rarely means new radiators. What actually matters: a proper system clean, an inhibitor, a filter and balanced radiators.
Read the guideTwo bathrooms, one boiler: can a combi serve two showers?
A combi heats water as it flows, so two showers share one supply. See what your mains and flow rate allow, and when a cylinder suits two bathrooms.
Read the guideHow long does a boiler last before replacing? When it is worth it
Most boilers last 10–15 years with annual servicing. See the signs that mean repair no longer pays and when to replace.
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Hot water cylinders
An unvented cylinder such as a Megaflo stores hot water at mains pressure, which is why it needs the right size, a qualified installer and regular checks. These guides cover sizing a cylinder, converting from a vented system and looking after an unvented one.
Brown water from the hot tap only: discoloured or smelly hot water compared
Brown water from the hot tap only points to the hot side of your plumbing. Compare discoloured and smelly hot water, and see who to call.
Read the guideConvert open vented heating system to sealed: what changes in your home
Converting an open vented heating system to sealed: the parts fitted, who may do the work, and what you check on the gauge afterwards.
Read the guideAdding an en-suite or second bathroom: will your hot water system cope?
Adding an en-suite or second bathroom? See when a combi still copes, when a system boiler and unvented cylinder suits, and what to check.
Read the guideVented or unvented hot water cylinder: how to tell which one you have
Loft tank, vent pipe or tundish: the checks that show whether your hot water cylinder is vented or unvented, and which suits your home.
Read the guideHot water cylinder loses heat overnight: gravity circulation up the vent, the draw-off and secondary pipework
Why a vented hot water cylinder goes cold overnight: gravity circulation in the vent and draw-off, the secondary return, and what you can check.
Read the guideCentral heating pump not working after summer: what the signs point to
Silent pump, humming or cold radiators after the summer? What you can check safely, and when a Gas Safe engineer is needed.
Read the guideCombi to system boiler conversion: going back to a hot water cylinder
Combi to system boiler conversion: when a system boiler fits, when a regular boiler fits, and what the rules in England require.
Read the guideWater leaking from the bottom of a hot water cylinder: where it comes from
A wet patch under your hot water cylinder is rarely the tank itself. See what leaks, what you can note and who may fix it.
Read the guideMegaflo hot water pressure drops after a few minutes: flow or temperature?
Megaflo hot water fading after a minute or two: tell a dropping flow rate from cooling water, and see what an engineer must check.
Read the guideImmersion heater: how long it takes to heat a tank, and when to use it as backup
Immersion heater heat-up times from manufacturer data sheets, what changes them, and when to use the immersion as a backup.
Read the guideHot water cylinder vent pipe regulations: what Part G requires in England
What Part G requires of a hot water cylinder vent pipe in England, why unvented cylinders have none, and the tundish rules.
Read the guideBalancing radiators: why some rooms never warm up
Why one room never warms up: how radiator balancing works, the four checks you can do safely, and when a Gas Safe engineer is needed.
Read the guideWhat temperature should a hot water cylinder be set to?
Store hot water at 60°C to control legionella, and limit bath outlets to 48°C in new homes in England. What to set, and who may adjust it.
Read the guideCan you fit a shower pump to a Megaflo or other mains-pressure cylinder?
A shower pump on a Megaflo is rarely the answer. See what the cylinder needs, what the water regulations require and what to check first.
Read the guideDo you need a new hot water cylinder with a new boiler?
Keeping your hot water cylinder when the boiler is replaced: when it can stay, when it cannot, and what the survey checks.
Read the guideHow long does an unvented cylinder or Megaflo last?
Unvented cylinder lifespan: what Megaflo, Ideal and Baxi warranties actually cover, and which faults shorten a cylinder's life.
Read the guideWho can install an unvented hot water cylinder in England?
In England, only a G3-qualified installer may fit an unvented cylinder. Here is what competence, notification and paperwork mean for you.
Read the guideDo unvented cylinders and Megaflo systems need an annual service?
Unvented cylinders and Megaflo units need a yearly service: what an engineer checks, why manufacturers ask for it and who may do it.
Read the guideWhat size hot water cylinder do you need?
How to size a hot water cylinder: occupants, bathrooms, peak demand, mains flow and recovery time, with the manufacturers' figures explained.
Read the guideConverting a vented system to an unvented cylinder
What converting a vented cylinder to an unvented system involves in England: Part G rules, water pressure checks and removing the loft tank.
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Underfloor heating
Underfloor heating spreads warmth across the whole floor instead of a few radiators, and it can go into a new floor or be retrofitted under an existing one. These guides cover what that involves before anything is lifted.
Underfloor heating: electric or gas, and which one to fit
Underfloor heating comes as electric mats or a wet system fed by a gas boiler. What differs, what the rules require, and which suits your room.
Read the guideElectric or water underfloor heating: which to fit in your home
Electric or water underfloor heating compared: running source, floor build-up, controls and which suits a single room or a whole house.
Read the guideUnderfloor heating or radiators: which suits the room you are planning
Underfloor heating or radiators? Compare flow temperature, floor coverings, fitting work and room use, and see which suits the room you are planning.
Read the guideWet or electric underfloor heating: which is better for your room
Wet underfloor heating heats a whole room from the boiler; electric mats suit one small room. How to choose, room by room, in England.
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Get in touch
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