You don’t need a specialist boiler for wet underfloor heating – the manifold’s mixing valve is what brings the boiler’s normal flow temperature down to the lower level underfloor pipework actually needs. Getting that mixing and control set-up right matters for comfort and running cost, and on some floor types it protects the flooring itself from heat damage.

Wet underfloor heating needs a much lower flow temperature than radiators

Underfloor heating works efficiently at significantly lower water temperatures than a typical radiator system – commonly designed around a flow temperature roughly in the range of 35–50°C, depending on the specific system, floor construction and insulation, compared with older radiator systems that have often historically run at 60–80°C. This lower operating temperature is one of the reasons underfloor heating pairs particularly well with heat pumps, which are most efficient at lower flow temperatures, but it works perfectly well with a standard gas boiler too – the boiler doesn’t need to run at UFH temperature itself, because of the manifold.

What the manifold actually does

The manifold is the hub that distributes hot water from your heating system out to the various underfloor heating loops or zones, and back again. Critically, it typically includes a mixing (or blending) valve, which takes the hotter water coming from the boiler and blends it with cooler water returning from the floor loops to bring the temperature down to the correct level before it’s sent into the underfloor pipework. This is what makes it possible to run a boiler at its normal operating temperature for the rest of the house while still supplying underfloor heating at the lower temperature it actually needs – the manifold does the temperature management, not the boiler itself.

Why getting this right matters

Sending water that’s too hot into underfloor pipework isn’t just inefficient – it can genuinely damage some types of flooring. Screed floors have maximum surface temperature limits, and some floor coverings, particularly certain solid wood floors, have manufacturer-specified maximum temperature and moisture tolerances because excess heat can cause shrinkage, warping or damage over time. A correctly set up manifold and control system is what keeps the floor within safe limits, which is why this isn’t a detail to leave to guesswork – it should be properly designed and commissioned as part of the installation.

Mixing underfloor heating with radiators in the same house

It’s common, especially in a retrofit, to have underfloor heating downstairs and radiators upstairs, run from the same boiler. This works by treating them as effectively separate temperature zones – the manifold blends the temperature down for the underfloor loops, while radiators are supplied at the boiler’s normal higher flow temperature, with zone valves and separate thermostatic control keeping the two circuits independently controllable. This is a design and control question as much as a plumbing one – it’s worth having a heating engineer confirm the zoning and controls are set up correctly, rather than assuming it will simply balance itself.

Underfloor heating responds more slowly than radiators – and that changes how you should control it

Screed-based wet underfloor heating systems typically have a lot of thermal mass, meaning the floor takes a while to heat up and, just as importantly, a while to cool down once the heating is turned off. This means underfloor heating generally doesn’t suit being switched rapidly on and off the way a radiator can be – it tends to work better run at a fairly steady, moderate level, with the room’s thermostat or a weather-compensating control managing gradual adjustments, rather than expecting a quick response the way you might from radiators. If your underfloor heating feels sluggish to respond, that’s often normal behaviour for the system type rather than a fault, though it’s still worth having it checked if it seems unusually slow even by underfloor heating standards.

Do you need a specific type of boiler?

No – combi, system and regular boilers can all supply an underfloor heating manifold, because the manifold, not the boiler, is what manages the temperature difference. What matters is that the whole system – boiler output, manifold, pipework sizing and controls – is designed and installed as a coherent system by someone competent in underfloor heating specifically, rather than assuming any boiler and any manifold will simply work together without proper design.

New build versus retrofit

The lowest, most efficient underfloor heating flow temperatures are generally achievable in a well-insulated new-build home, where the floor construction and insulation levels are designed around underfloor heating from the outset. Retrofitting underfloor heating into an older, less well-insulated property is still very possible, and is commonly done as part of a renovation, but the achievable flow temperature and overall efficiency will depend more on the property’s existing insulation and floor build-up – a good installer should assess this as part of designing the system, rather than applying a generic flow temperature figure regardless of the property.

A quick note on electric underfloor heating

Everything above concerns wet, water-based underfloor heating connected to a boiler or heat pump. Electric underfloor heating, which uses heating cables or mats instead of water pipes, is a genuinely different system with no manifold or boiler connection at all – it’s wired into the electrical supply and controlled by its own thermostat. It’s commonly used for smaller areas like bathrooms rather than whole-house heating, largely because running costs on electric underfloor heating are usually higher than a boiler or heat pump-fed wet system for larger areas. If you’re planning whole-house underfloor heating, the wet system described in this guide is almost always the more practical and cost-effective route.

Frequently asked questions

Do you need a special boiler for underfloor heating?

No. Combi, system and regular boilers can all supply an underfloor heating manifold, because it is the manifold – not the boiler – that manages the temperature difference between the boiler’s normal output and the lower temperature underfloor pipework needs.

What stops the water sent to underfloor pipework from being too hot?

The manifold’s mixing (or blending) valve, which takes the hotter water from the boiler and blends it with cooler water returning from the floor loops to bring it down to the correct temperature before it enters the underfloor pipework.

Can underfloor heating and radiators run from the same boiler?

Yes. This is common in retrofits, with underfloor heating downstairs and radiators upstairs treated as separate temperature zones – the manifold blends the temperature down for the underfloor loops while radiators still run at the boiler’s normal higher flow temperature.

Sources

• Energy Saving Trust – heating controls and system design
• Heating and Hotwater Industry Council (HHIC)
• Gas Safe Register

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A condensing boiler recovers extra heat from its flue gases by condensing water vapour out of the exhaust, which is why it needs a condensate pipe that a non-condensing boiler never had. Since 2005, Building Regulations in England and Wales have required new gas boiler installations to be condensing in almost all cases, which is why non-condensing boilers are now rare outside older, unreplaced installations.

What actually makes a boiler “condensing”

A condensing boiler is designed to extract additional heat from the flue gases before they leave the boiler, by cooling them enough that water vapour within the exhaust condenses back into liquid, releasing extra latent heat in the process that a non-condensing boiler simply loses up the flue. A non-condensing (sometimes called a “regular” or traditional) boiler vents its exhaust gases while they’re still hot, without recovering that extra heat, which is why non-condensing boilers are meaningfully less efficient – older non-condensing boilers commonly operated in a lower efficiency range, while a modern condensing boiler, run under the right conditions, can reach considerably higher efficiency by comparison.

Why condensing boilers need a condensate pipe, and non-condensing ones don’t

Condensing the water vapour out of the flue gases produces an actual liquid – mildly acidic condensate – that has to be safely drained away, which is why condensing boilers have a condensate pipe running to an internal or external drain. Non-condensing boilers don’t produce this liquid in the same way and don’t have this pipe at all. This is also directly why frozen condensate pipes are a winter problem specific to condensing boilers – a non-condensing boiler was never at risk of this particular fault, simply because it doesn’t have the pipe to freeze in the first place.

The regulatory reason condensing boilers became standard

Since 2005, Building Regulations in England and Wales (under Approved Document L, covering conservation of fuel and power) have required that new gas boiler installations be condensing boilers in almost all standard circumstances, effectively phasing non-condensing boilers out of new installations from that point. Scotland and Northern Ireland run their own separate building standards systems, with broadly similar requirements introduced around a similar period, though the exact regulatory detail and timing differs by nation – if you need the precise position for Scotland or Northern Ireland, check the relevant national building standards guidance directly rather than assuming the England and Wales dates apply exactly.

Are non-condensing boilers ever still fitted today?

Very rarely, and only where there’s a genuine, specific, documented reason condensing simply isn’t practical – for example, certain constrained installations where there’s no viable route to safely dispose of condensate, or specific heritage or listed-building constraints affecting what can be installed. These are narrow exceptions, assessed case by case, not a general alternative route available to anyone who’d simply prefer a non-condensing boiler. If you have an older non-condensing boiler still running today, it’s most likely because it predates the 2005 requirement and hasn’t yet been replaced, rather than because it was a recent, deliberately chosen installation.

Should you replace an old non-condensing boiler?

Given the efficiency gap between the two types, replacing a genuinely old non-condensing boiler with a modern condensing model is one of the more reliable ways to reduce heating costs over time, though exactly how much you’d save depends heavily on your current boiler’s actual condition and efficiency, your home’s heat demand, and your heating patterns – it’s worth getting a proper, honest estimate for your specific situation rather than relying on a generic percentage figure.

What this means if you’re buying a home with an older boiler

If a survey or your own inspection identifies a non-condensing boiler in a property you’re buying, it’s worth treating that as a genuine cost to factor into your decision rather than a minor detail. Beyond the higher running costs, an old non-condensing boiler is, by definition, at least two decades old given the 2005 regulatory change, which means it’s also likely to be near or past the end of its practical working life regardless of the condensing question – parts availability and the risk of a costly breakdown both tend to rise sharply on boilers of that age. Ask when it was last serviced, whether service records exist, and get a heating engineer’s honest opinion on its remaining lifespan before you rely on it continuing to work reliably.

Servicing and maintenance differences

Day to day, servicing a condensing boiler involves a few extra checks that simply don’t apply to a non-condensing model – checking the condensate trap and pipe are clear and not damaged, and confirming the condensate drains correctly, alongside the standard checks that apply to any gas boiler service such as combustion analysis, checking the flue, and inspecting for corrosion or leaks. This is a normal part of an annual service on a condensing boiler and isn’t something to be concerned about, but it’s worth knowing that “servicing a boiler” isn’t quite identical between the two types, even though the core safety checks are the same.

Frequently asked questions

What’s the actual difference between a condensing and non-condensing boiler?

A condensing boiler cools the flue gases enough that water vapour in the exhaust condenses back into liquid, recovering extra heat a non-condensing boiler simply loses up the flue – which is also why only condensing boilers have a condensate pipe.

Can a non-condensing boiler still be installed today?

Very rarely. Building Regulations in England and Wales have required new gas boiler installations to be condensing since 2005, so non-condensing boilers are now fitted only in narrow, documented exceptions, such as installations with no viable route to drain condensate.

Does servicing a condensing boiler differ from a non-condensing one?

Yes, slightly. A condensing boiler service includes checking the condensate trap and pipe are clear and undamaged, on top of the standard checks – such as combustion analysis and inspecting the flue – that apply to any gas boiler service.

Sources

• GOV.UK – Approved Document L: conservation of fuel and power
• Energy Saving Trust – boiler efficiency guidance
• Gas Safe Register – condensing boilers

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Landlords in Great Britain must have every gas appliance they supply checked annually by a Gas Safe registered engineer, and give tenants the resulting safety record within set deadlines. Missing those deadlines is a criminal offence enforced by the HSE, and in England it can also invalidate a Section 21 eviction notice.

What “CP12” actually refers to

This article covers landlord gas safety obligations in Great Britain under the Gas Safety (Installation and Use) Regulations 1998. It is general information, not legal advice – if you’re a landlord, check the current detailed requirements with the HSE or a qualified adviser.

Landlords and tenants often refer to a landlord’s gas safety check informally as a “CP12,” which comes from an older industry form reference. The current, correct term for the document a landlord must provide is a Gas Safety Record (sometimes called a Landlord Gas Safety Record), but if you hear “CP12” mentioned, this is what people mean – the annual safety check record for gas appliances, pipework and flues in a rented property.

What the law actually requires

Under the Gas Safety (Installation and Use) Regulations 1998, landlords in Great Britain must have every gas appliance and flue that they own and that serves the rented property checked for safety by a Gas Safe registered engineer at least once every 12 months. This isn’t limited to boilers – it covers any gas appliance the landlord has supplied, such as gas fires, gas cookers if provided by the landlord, and gas water heaters, along with associated pipework and flues. A tenant’s own gas appliance that they brought with them and installed themselves generally sits outside the landlord’s direct responsibility for the appliance itself, though flues and pipework serving it may still be relevant – if you’re unsure where the line falls in a specific situation, check with a Gas Safe registered engineer or the HSE’s guidance directly.

Giving the record to tenants: specific deadlines apply

It isn’t enough to just have the check done – landlords are required to give a copy of the current gas safety record to existing tenants within 28 days of the check being carried out, and to give a copy to a new tenant before they move into the property. Landlords are also required to keep copies of gas safety records for a minimum period – generally the last two years’ worth of records – so they can be produced if needed.

Why this matters beyond just compliance

Failing to meet these requirements is a criminal offence, enforced by the Health and Safety Executive, and can result in prosecution, with penalties including a fine and, in the most serious cases, imprisonment. There’s also a specific practical consequence for landlords in England worth knowing about directly: a valid gas safety record generally has to have been provided to the tenant before a landlord can serve a valid Section 21 “no fault” eviction notice under an assured shorthold tenancy – if it wasn’t provided correctly, the Section 21 notice can be invalid, regardless of how straightforward the rest of the case might otherwise be. This specific rule relates to England’s tenancy system; Scotland and Wales have different tenancy frameworks, without a direct equivalent to England’s Section 21 process, so this particular consequence doesn’t translate directly across all three nations even though the underlying gas safety check requirement applies across Great Britain.

Who can carry out the check

Only a Gas Safe registered engineer can legally carry out a landlord gas safety check, and they need to be registered for the specific type of work and appliance involved – the same point that applies to installing or servicing any gas appliance. Always ask to see the engineer’s Gas Safe ID card and check it covers the relevant type of work before they start, rather than assuming any tradesperson describing themselves as a “gas engineer” is appropriately registered.

Practical checklist for landlords

• Book the annual gas safety check with enough lead time that it doesn’t lapse past the 12-month point;
• Confirm the engineer is Gas Safe registered for the relevant appliance types before the visit;
• Provide the record to existing tenants within 28 days, and to new tenants before they move in;
• Keep at least the last two years of records on file;
• If you’re in England and may need to serve a Section 21 notice at any point, make sure your gas safety paperwork is genuinely in order well before that becomes relevant.

What tenants should do with the record once they get it

Keep a copy somewhere you can find it, and check the date on it rather than assuming it’s automatically been renewed each year – you’re entitled to ask your landlord or letting agent for the current record if you haven’t received one recently, or if you’re not sure whether the last check has actually happened. If a landlord is unresponsive about providing a gas safety record, or you have any reason to suspect gas appliances in the property haven’t been checked, you can raise it directly with the landlord in writing first, and escalate to the local council’s private housing team or the HSE if it isn’t resolved – gas safety isn’t a matter to let slide because of an awkward conversation with a landlord.

Smoke and carbon monoxide alarms: a related but separate landlord duty

Alongside the gas safety check itself, landlords in England have separate legal duties around smoke alarms on every storey used as living accommodation, and carbon monoxide alarms in rooms containing certain fuel-burning appliances. These requirements come from different regulations to the gas safety check itself, but they’re worth mentioning together because they form part of the same overall picture of a landlord’s fire and gas safety obligations – a property can be compliant on its annual gas safety check and still fall short on alarm requirements, so don’t treat one as covering the other.

Frequently asked questions

How often must a landlord gas safety check happen?

At least once every 12 months, for every gas appliance and flue the landlord owns and that serves the rented property, carried out by a Gas Safe registered engineer.

How quickly must a landlord give tenants the gas safety record?

Within 28 days of the check for existing tenants, and before a new tenant moves in. Landlords must also keep copies of records for a minimum of the last two years.

Can a missing gas safety record affect a Section 21 eviction notice?

Yes, in England. A valid gas safety record generally has to have been provided to the tenant before a landlord can serve a valid Section 21 “no fault” eviction notice – if it wasn’t provided correctly, the notice can be invalid.

Sources

• Health and Safety Executive – landlords: gas safety responsibilities
• GOV.UK – renting out your property: gas safety
• Gas Safe Register

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ECO4 and the Great British Insulation Scheme are both government-mandated efficiency schemes, but only ECO4 can ever touch boiler-related work, and even then only in narrow, specific circumstances. GBIS funds insulation only, and if you actually want help with a low-carbon heating upgrade, the separate Boiler Upgrade Scheme is the one to look at instead.

Two different schemes that people often mix up

Government-backed energy efficiency schemes in Great Britain change fairly often – eligibility criteria, funding levels and even which scheme is currently running are periodically updated. The mechanisms described below reflect how these schemes have generally worked; always check GOV.UK or Ofgem directly for the current scheme name, phase and eligibility rules before assuming anything here still applies exactly as written.

ECO (the Energy Company Obligation) and the Great British Insulation Scheme (GBIS) are both government-mandated schemes that require energy suppliers to fund home efficiency improvements, but they cover different things and different households – conflating them is one of the most common sources of confusion, particularly around whether either one will pay for a new boiler.

ECO4: targeted at low-income and vulnerable households

ECO is a long-running obligation placed on larger energy suppliers, requiring them to fund energy efficiency measures for specified groups of households, primarily targeted through two main eligibility routes: households receiving certain means-tested benefits, or households referred through their local authority’s “flexible eligibility” route for people who are low-income or vulnerable but don’t receive a qualifying benefit directly. ECO funding has generally supported a fairly broad range of measures – insulation, heating controls, and in some circumstances central heating or boiler work – but boiler-related support under ECO has typically been tied to a whole-house approach and specific circumstances, such as a broken or condemned heating system, rather than functioning as a general “get a free new boiler” offer for anyone who applies. Don’t assume boiler replacement is automatically included; check what measures you’d actually be assessed for as part of an ECO application.

The Great British Insulation Scheme: insulation only, not boilers

This is the distinction most worth getting right: the Great British Insulation Scheme is specifically an insulation scheme – it does not fund boiler replacement. It’s aimed at a somewhat broader group of households than the benefits-based ECO route, generally combining a property’s Council Tax band and its current EPC rating as eligibility criteria, alongside a separate low-income eligibility route. If you’re specifically looking for help with the cost of a new boiler, GBIS is not the scheme to apply through – it’s worth applying to if loft, cavity wall or similar insulation is what you actually need, but it won’t fund a heating system upgrade.

If you’re actually looking for help with a new heating system

Separately from both of the above, the Boiler Upgrade Scheme (BUS) provides a grant voucher toward the cost of installing a heat pump or, in some circumstances, a biomass boiler, in England and Wales – but it is specifically aimed at low-carbon heating installations, not at replacing an old gas boiler with a new one. If what you actually want is straightforward help with a standard gas boiler replacement, none of ECO4, GBIS or BUS is designed as a general-purpose grant for that – ECO4’s boiler-related support, where it exists, is narrowly targeted through the eligibility routes described above, rather than being available on request.

Scotland and Wales run their own additional schemes

ECO applies across Great Britain, but Scotland and Wales also run their own separate national schemes alongside it – for example, support delivered through Home Energy Scotland in Scotland, and the Welsh Government’s Nest scheme in Wales – with their own eligibility criteria and application routes, distinct from the England-specific detail of some England-only schemes. If you’re in Scotland or Wales, check the relevant national scheme directly rather than assuming an England-focused scheme description applies to you.

How to actually check what you might qualify for

• Use GOV.UK’s or Ofgem’s current eligibility checker rather than relying on older articles or a supplier’s marketing claims;
• Have your Council Tax band, EPC rating and any relevant benefits information ready, since these are common eligibility criteria across these schemes;
• Be cautious of any company cold-calling or door-knocking offering a “free boiler grant” – go through the official GOV.UK or Ofgem routes to check genuine eligibility rather than relying on a salesperson’s claim;
• If you’re in Scotland or Wales, check the national scheme for your nation specifically, alongside GB-wide ECO eligibility.

Watch out for who’s actually delivering the work

Because these schemes are funded through energy suppliers rather than paid directly by government, the actual installation is usually carried out by an approved installer working within the scheme rather than the supplier itself turning up at your door. Genuine scheme installers should be able to confirm which scheme they’re operating under and show relevant accreditation – a legitimate installer won’t be reluctant to explain exactly how the funding works or to put things in writing. If someone’s approach feels rushed, vague about the specific scheme name, or focused on getting a signature quickly rather than properly assessing your home, that’s worth treating as a warning sign regardless of how genuine the underlying government scheme is.

What if you don’t qualify for any of these?

Not qualifying for ECO4 or GBIS doesn’t mean there’s no support available at all – it just means you’re outside the specific eligibility criteria for those particular schemes at this point in time. It’s worth periodically rechecking, since eligibility criteria and scheme phases do change, and worth asking your energy supplier directly whether they offer any additional, supplier-specific support alongside the mandatory schemes, which some do on top of their regulatory obligations.

Frequently asked questions

Will ECO4 or GBIS pay for a new boiler?

GBIS never funds boiler replacement – it’s insulation only. ECO4 can sometimes support boiler-related work, but only tied to a whole-house approach and specific circumstances, such as a broken or condemned heating system, not as a general “free boiler” offer.

What if I want help with a heat pump instead of a new gas boiler?

That’s the Boiler Upgrade Scheme (BUS), not ECO4 or GBIS. BUS provides a grant voucher toward installing a heat pump, or in some circumstances a biomass boiler, in England and Wales.

How do I check what I might actually qualify for?

Use GOV.UK’s or Ofgem’s current eligibility checker rather than an older article or a supplier’s marketing claim, and have your Council Tax band, EPC rating and any relevant benefits information ready.

Sources

• GOV.UK – help with energy bills and home upgrades
• Ofgem – Energy Company Obligation (ECO)
• Ofgem – Great British Insulation Scheme
• Ofgem – Boiler Upgrade Scheme

Related guides

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LPG heating is delivered to a bulk tank on your property rather than piped in, and the boiler itself needs to be factory-configured or converted for LPG rather than simply run on a standard mains-gas boiler. LPG is also heavier than air, unlike natural gas, which is a genuine safety factor in how tanks and installations are sited and ventilated.

What LPG actually is, and how it gets to your boiler

LPG (liquefied petroleum gas) used for home heating is generally propane, stored as a liquid under pressure and delivered to your property rather than piped in from a national network. For whole-house central heating, the standard setup is a bulk storage tank installed on your property, refilled periodically by a tanker delivery, rather than gas bottles – bottled gas is more suited to smaller-scale or temporary use than to running a full central heating system continuously through winter.

Owning your tank versus a supplier-owned tank

There are generally two ownership models, and the difference matters financially. You can buy your own bulk tank outright, which typically lets you shop around and choose whichever LPG supplier offers the best price for each refill, similar in principle to how heating oil customers compare suppliers. Alternatively, a supplier can provide and install a tank on a leased or free-issue basis, which usually reduces your upfront cost but commonly ties you to buying gas exclusively from that supplier, sometimes for a fixed initial term. Before agreeing to a supplier-owned tank, check the tie-in terms carefully – a lower upfront cost can be offset by less competitive gas pricing over the life of the tank if you can’t switch supplier freely.

The boiler itself needs to be set up for LPG specifically

A boiler designed for mains natural gas is not simply interchangeable with LPG without modification. LPG boilers either come from the manufacturer already configured for LPG, or a standard boiler is converted using a specific LPG conversion kit, with different injectors or jets sized for the different gas. This isn’t a job for a general gas engineer working outside their registration: Gas Safe Register, the official registration body for gas engineers in the UK, has separate categories of registration for LPG work distinct from mains natural gas – always check that whoever is installing or servicing your LPG boiler is specifically registered for LPG, not just gas work generally, since the two aren’t automatically the same qualification.

A genuine safety difference from mains gas: LPG is heavier than air

This is worth understanding clearly rather than assuming LPG behaves like natural gas in a leak. Natural gas is lighter than air and disperses upwards; LPG is heavier than air, which means that if it leaks, it tends to sink and can pool in low-lying areas – cellars, pits, or other spaces close to ground level – rather than dispersing safely upward. This is a real factor in how LPG systems, tanks and any indoor components need to be sited and ventilated, and it’s part of why LPG installations follow their own specific industry safety guidance rather than simply mirroring natural gas installation practice.

Tank siting and safety distances

Bulk LPG tanks need to be sited with appropriate separation distances from buildings, boundaries and any sources of ignition, in line with industry safety guidance, and the site needs safe, practical access for the tanker to carry out refills. This isn’t something to finalise casually in whatever corner of the garden looks convenient – get advice from your installer or supplier on siting requirements before the tank goes in, since moving it later is far more disruptive than getting it right the first time.

Running costs and efficiency

Once installed, an LPG boiler works on broadly the same efficiency principles as a mains gas boiler – the same ErP and efficiency banding concepts apply, and a modern condensing LPG boiler is significantly more efficient than an older non-condensing model, just as with mains gas. LPG typically costs more per unit of energy than mains gas, which is a genuine ongoing cost consideration for off-grid homes, though it’s usually still cheaper to run per unit than heating oil equivalents in many comparisons – get current, like-for-like quotes for your specific area and usage rather than relying on general comparisons, since relative pricing between LPG, oil and electricity shifts with the wider energy market.

Practical checklist before choosing LPG

• Compare customer-owned versus supplier-owned tank arrangements, and read any tie-in terms carefully;
• Confirm your installer and any future servicing engineer are specifically Gas Safe registered for LPG work;
• Check the proposed tank siting against safety distance guidance before installation, not after;
• Get current running cost comparisons against oil and other off-grid options for your specific household.

Frequently asked questions

Can a standard mains-gas boiler be used with LPG?

Not without modification. LPG boilers are either factory-configured for LPG or converted using a specific LPG conversion kit with different injectors, and installation or servicing must be carried out by an engineer specifically Gas Safe registered for LPG work.

Is LPG more dangerous than mains gas if it leaks?

It behaves differently. Natural gas is lighter than air and disperses upwards, while LPG is heavier than air and can pool in low-lying spaces such as cellars or pits, which is why LPG tanks and installations follow their own specific siting and ventilation guidance.

Is LPG cheaper to run than heating oil?

LPG typically costs more per unit than mains gas, but is usually still cheaper per unit than heating oil in many comparisons – get current, like-for-like quotes for your specific area and usage rather than relying on general comparisons.

Sources

• Gas Safe Register
• Liquid Gas UK – LPG industry guidance
• Health and Safety Executive – LPG storage and use

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An efficiency rating tells you how much of the fuel a boiler burns is turned into usable heat, not how much your household will actually spend on gas. Two boilers with the same letter can still leave you with different bills, because the label covers the appliance in isolation, not how it is controlled, sized or used in your home.

What the label is actually measuring

UK boiler efficiency labelling comes from the EU’s Energy related Products (ErP) framework, retained in UK law after leaving the EU. It applies to gas, oil, LPG and electric boilers up to 70kW, along with hot water storage tanks and water heaters, and requires an energy label with a letter grade at the point of sale.

The figure behind the letter is a seasonal efficiency percentage: broadly, how much of the energy in the fuel is converted into heat across a typical heating season, rather than lost up the flue or through standing losses. It is a laboratory measure of the appliance, tested under standard conditions – not a promise about your specific gas bill.

ErP vs SEDBUK: why you may see both terms

SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK) is the older UK rating system, also graded A to G, that predates the current ErP label. You will still see SEDBUK figures referenced in older paperwork, some manufacturer technical documents and building-compliance software, because the underlying efficiency data feeds into Building Regulations energy calculations as well as the retail ErP label.

For a buyer today, ErP is the label you will actually be shown on a quote or a boiler’s technical data sheet. SEDBUK figures are worth asking about only if you are comparing an older boiler already installed in a property against a new one, or if a survey or EPC assessment refers to them.

Why almost every new boiler says “A-rated”

Since April 2018, the Boiler Plus standard has set a minimum performance requirement for new domestic gas boiler installations in England: every new gas boiler must achieve at least 92% ErP seasonal efficiency, which sits within the A band. In practice, this means it is now unusual to find a new gas boiler on the UK market that is not A-rated – the label alone no longer separates a good installation from a mediocre one, because almost everything sold today clears the same bar.

This is genuinely useful context when you are comparing quotes: if every combi, system or regular boiler on your shortlist is A-rated, the letter is not the differentiator. What differs between installers and models is everything Boiler Plus added on top of the appliance rating.

The part of the label that still varies: controls

Alongside the 92% minimum, Boiler Plus requires every new gas boiler installation to include basic time-and-temperature control (a programmer and thermostat, if not already fitted and working), and for combi boiler installations specifically, at least one of four additional measures:

• Flue gas heat recovery – recovers some heat from the flue gases to preheat incoming water;
• Weather compensation – adjusts the boiler’s output automatically based on the outside temperature;
• Load compensation – adjusts the boiler’s output based on how close the room is to the target temperature; or
• A smart thermostat with standalone automation and optimisation – learns your household’s patterns and adjusts run times accordingly.

These measures are not reflected in the ErP letter itself, but they materially affect how efficiently the boiler runs in your actual home, day to day. This is a genuinely useful question to ask an installer: not “what rating is this boiler?” – the answer will almost always be A – but “which of the four measures is included, and why that one for my home?”

What to actually compare when you get quotes

With the ErP letter largely equalised across the market, focus comparisons on the things that still vary between installers and models:

• which control measure (of the four above) is proposed, and whether it suits how the household actually uses heating;
• the boiler’s modulation range – how far it can turn its output down, which affects efficiency at part-load, which is most of the time in a well-insulated home;
• correct sizing for the property’s heat loss and hot-water demand, since an oversized boiler run at part-load performs worse in practice than its rated efficiency suggests;
• whether the quoted price includes the full Boiler Plus-compliant control package, or whether it is an optional extra; and
• that installation is carried out and signed off by a Gas Safe registered engineer, which is a legal requirement for any gas boiler work in Great Britain, separate from the efficiency question but essential to check regardless.

Frequently asked questions

Does a higher ErP rating always mean a lower gas bill?

Not on its own. The rating measures the appliance under test conditions. Your actual bill depends on the rating combined with correct sizing, the controls fitted, how the household uses heating, insulation, and gas prices. Two A-rated boilers can produce different real-world bills in the same house.

Is it worth replacing a working boiler purely to get a better rating?

Not as a standalone reason. If your current boiler is a non-condensing model installed before condensing boilers became standard, replacement is likely to improve efficiency meaningfully. If it is already a reasonably modern condensing boiler, the efficiency gain from replacement alone is smaller, and the decision is better made on reliability, parts availability and running costs together – not the label alone.

Do electric boilers carry the same ErP letter scale?

Electric boilers and water heaters fall under the same ErP framework but are assessed differently from combustion appliances, since there is no flue loss to account for. A high ErP letter on an electric boiler does not by itself tell you whether electric heating will cost more or less to run than gas in your home – that depends on your electricity and gas unit rates.

Sources

• Boiler Plus: new standards for domestic boiler installations from April 2018 – GOV.UK factsheet
• Find or check a Gas Safe registered engineer – Gas Safe Register

Related guides

Best Boiler Deals is an independent guide. We may earn a fee from some links; this never affects what we write.

Zoning splits a home’s heating into two or more independently controlled areas, rather than one thermostat deciding the temperature for the entire house. It is a controls and pipework decision, not a different type of boiler – and it is worth understanding what it actually changes before paying to have it fitted.

What zoning actually means

In an unzoned system, a single room thermostat – usually in the hallway or living room – calls for heat on behalf of the whole house. Every radiator with an open thermostatic valve responds to that one call, regardless of whether the room it is in actually needs heat. Zoning adds additional two-port zone valves and, usually, a second thermostat or programmer, so that one part of the house (commonly upstairs versus downstairs, or an extension versus the original house) can be heated on a separate schedule and to a separate target temperature from the rest.

How a zoned system is built

Technically, zoning is achieved with additional motorised two-port valves plumbed into the pipework for each zone, wired back to a control panel (a wiring centre) alongside the extra thermostats or programmers. This is a pipework and controls addition, not something exclusive to one type of boiler – combi, system and regular boilers can all, in principle, feed a zoned pipework layout, because the zoning happens downstream of the boiler rather than inside it. What differs between boiler types is how practical and disruptive the retrofit is, which depends more on existing pipe runs and access than on the boiler itself.

Zoning vs weather and load compensation

It is easy to conflate zoning with the weather compensation and load compensation controls now required on many new combi boiler installations under the Boiler Plus standard. They solve different problems. Compensation controls adjust how hard the boiler works based on outside temperature or how close a room is to its target – they affect the boiler’s output, not which rooms receive heat. Zoning controls where heat goes within the house. A well-controlled but unzoned system can still heat an entire house to one temperature very efficiently; it simply cannot heat only part of it. The two approaches are complementary rather than substitutes for each other.

Homes where zoning tends to pay off

Zoning tends to be worth considering in:

• larger homes over two or more storeys, where upstairs bedrooms and downstairs living space genuinely need heat at different times of day;
• homes with an extension or converted space added after the original system was designed, where the addition is currently on the same single zone as the rest of the house regardless of how it is actually used;
• households with markedly different occupancy patterns between areas – for example, a home office or annexe used on a different schedule from the main living space; and
• larger properties where TRVs alone are not giving enough separation, because the single thermostat is satisfied by one part of the house while radiators elsewhere are still calling for heat through open valves.

In a smaller, single-storey or open-plan home used fairly uniformly through the day, a well-set programmer, thermostat and TRVs will often achieve most of the same practical benefit without the cost of adding zone valves and a second control circuit.

What retrofitting zones actually involves

Adding zoning to an existing, unzoned system means new pipework and wiring, which usually involves lifting floorboards or accessing the loft to run cables and valves to the right locations, plus a second thermostat or programmer and the wiring centre to control it. This is more straightforward, and usually cheaper, when it is planned alongside a boiler replacement or a wider heating system refurbishment, when pipework is already being disturbed, than as a standalone retrofit to a system that is otherwise untouched. As with any work affecting the gas appliance or its controls, get quotes from, and have the work carried out by, a Gas Safe registered engineer.

Frequently asked questions

Does zoning work with a combi boiler?

Yes. Zoning is implemented in the pipework and controls downstream of the boiler, so it can be added to a combi, system or regular boiler installation. The practicality of retrofitting it depends on existing pipe runs and access in your specific property, not the boiler type itself.

Is zoning the same as smart heating controls?

No, though they are often installed together. A smart thermostat usually still controls one zone more intelligently (learning schedules, remote control, geofencing); zoning is the separate decision to have more than one controllable area in the first place. You can have smart control of a single zone, or basic controls across several zones.

Will zoning definitely reduce my heating bill?

It reduces the amount of heat sent to areas that do not currently need it, which is generally beneficial, but the actual saving depends on how differently the zones are used, how well-insulated each area is, and how the system is set up and used day to day. There is no universal figure that applies to every home, so treat any specific percentage saving you see quoted with caution unless it is based on your own property.

Sources

• The most economical ways to use your central heating – Energy Saving Trust
• Boiler Plus: new standards for domestic boiler installations from April 2018 – GOV.UK factsheet
• Find or check a Gas Safe registered engineer – Gas Safe Register

Related guides

Best Boiler Deals is an independent guide. We may earn a fee from some links; this never affects what we write.

Boiler cover and service plans are ongoing paid products, separate from the guarantee that came with the boiler when it was installed. Before buying one, or renewing one automatically, it is worth checking what you already have and reading what the plan actually promises to pay for.

Check whether you already have cover

Citizens Advice guidance points out that boiler or home emergency cover is sometimes already included, and households pay for a second, overlapping plan without realising it. Before buying a standalone policy, check:

• whether your home insurance already includes home emergency or boiler breakdown cover;
• whether a packaged bank account you hold includes boiler or home emergency cover as a benefit; and
• whether an employer benefit or a scheme you already pay into covers a broken boiler.

If more than one policy could apply, compare the terms and conditions rather than assuming either one is sufficient, since cover levels and exclusions between a bundled benefit and a dedicated boiler plan can differ significantly.

What a boiler cover plan typically includes

Plans vary between providers, but the areas to check on any policy are the same:

• Parts and labour – is a breakdown call-out included, and are both parts and labour covered, or only one;
• Annual service – is a yearly service included as part of the plan, or charged separately;
• Response times – what is promised for how quickly an engineer will attend, particularly if the household has no other heating source;
• Call-out limits – whether there is a cap on the number of call-outs or total claim value per year; and
• Excess – any fixed fee you pay per claim regardless of the fault.

Read the exclusions, not just the headline cover

The exclusions section is usually where the real difference between plans shows up. Common exclusions worth checking for specifically include pre-existing faults, sludge or scale damage where the system has not been maintained, inaccessible pipework, third-party heating controls not supplied by the provider, and a requirement that the boiler has been regularly serviced – sometimes specifically by that provider – for a claim to be valid. If a provider is entitled to declare the boiler “beyond economical repair” rather than fix it, check what that means for your policy: whether you receive a contribution towards replacement, or simply a refund of remaining premiums.

Cover plan vs manufacturer guarantee vs warranty

A cover plan is not the same thing as the guarantee that came with a new boiler at installation. A manufacturer guarantee is typically free, tied to the specific appliance, and usually requires proof of annual servicing to remain valid – it does not need a monthly payment to keep going. A cover plan is a separate, paid product that can extend protection beyond the manufacturer guarantee, cover call-outs for other parts of the heating system, or provide cover once the manufacturer guarantee has expired. If your boiler is still within its manufacturer guarantee period, check what a cover plan actually adds on top of that before paying for both.

Renters and landlords

If you rent your home, Citizens Advice is clear that your landlord is responsible for repairing or replacing a broken boiler once you have reported the fault, and this is not something a tenant needs a separate cover plan to arrange. Landlords, in turn, are legally required to have gas appliances checked annually by a Gas Safe registered engineer and to provide tenants with a current gas safety record.

Whoever attends, check they are Gas Safe registered

Regardless of which cover plan or provider you use, only a Gas Safe registered engineer is legally permitted to work on a gas boiler in Great Britain. Ask to see the engineer’s ID card when they arrive, and check what work they are qualified to carry out – not every registered engineer is qualified for every type of gas appliance. You can check an individual’s registration using their licence number on the Gas Safe Register website before work begins.

Frequently asked questions

Is boiler cover worth buying for a brand-new boiler?

Often not immediately, if the boiler is already covered by a manufacturer guarantee. Check what the guarantee covers and for how long before adding a paid plan on top – a cover plan becomes more relevant as the guarantee period runs out.

Does boiler cover include the annual service needed to keep a manufacturer guarantee valid?

Sometimes, but not always – check the policy specifically. If it does not, you still need to arrange and keep evidence of an annual service yourself to avoid invalidating the separate manufacturer guarantee.

Can a cover plan refuse a claim because the system was not serviced?

Yes, this is one of the most common exclusions. Missing or unproven servicing history is a frequent reason plans decline to pay out, which is why keeping service records matters even after you have taken out cover.

Sources

• Getting your broken boiler repaired or replaced – Citizens Advice
• Find or check a Gas Safe registered engineer – Gas Safe Register

Related guides

Best Boiler Deals is an independent guide. We may earn a fee from some links; this never affects what we write.

A new boiler is not the first or the cheapest lever for a lower heating bill. Most homes still have unused savings available from the controls, insulation and system maintenance they already have, before a replacement boiler is the right next step.

Start with how the heating is actually used

Ofgem and Energy Saving Trust guidance both start in the same place: use less energy for heating by lowering your thermostat and turning down radiators in rooms that are not in regular use, rather than heating the whole house to one uniform temperature all day. If your heating is currently on a single blanket schedule regardless of occupancy, that is usually the first and cheapest thing to change – it costs nothing and does not require an engineer visit.

Get the existing controls doing their job

Most homes already own the hardware needed to cut waste; it is often not being used properly:

• Programmer or timer – set heating and hot water to come on only when the home is occupied, rather than running to a default all-day schedule;
• Room thermostat – check it is set to the lowest temperature that is still comfortable, and not simply left wherever it was set when the system was installed;
• Thermostatic radiator valves (TRVs) – turn individual radiators down or off in spare rooms, box rooms and rooms used only occasionally, rather than heating them to the same level as living spaces; and
• Smart thermostats and heating controls – where fitted, use scheduling and geofencing properly so the heating is not running to an empty house.

Energy Saving Trust’s guidance on taking control of home heating makes the same point: a programmer, thermostat and TRVs working together, used properly, let you heat only the rooms and times you need – rather than assuming the fix for a high bill is always a new appliance.

Reduce heat loss before you touch the boiler

A boiler, old or new, is heating a leaky or well-insulated home equally hard depending on how much heat escapes. Ofgem’s household energy advice specifically flags insulating your hot water tank or cylinder, and blocking gaps around windows and doors, as straightforward steps that reduce how much heat is lost before it even reaches the room. Other low-cost checks worth doing on an existing system:

• lag any exposed pipework in unheated spaces, such as a loft or garage, so heat is not lost in transit;
• bleed radiators that are cold at the top but warm at the bottom – trapped air makes the pump and boiler work harder for the same heat output;
• check loft and cavity wall insulation levels if the property has not been assessed recently, since these are longer-term but often high-value improvements; and
• draught-proof doors, letterboxes and unused chimneys, which lose heat continuously regardless of how efficient the boiler itself is.

Keep the system itself running cleanly

An unserviced or sludged-up system loses efficiency gradually, often without an obvious fault. An annual service by a Gas Safe registered engineer keeps the boiler running as intended and can catch early signs of scale or debris in the system before they affect performance. If radiators are cold in patches, or the system has never been power-flushed since installation, that is worth investigating before assuming the boiler itself needs replacing – a full replacement does not fix a dirty system if the same water and debris go back in.

Check your tariff and support schemes

Some of the largest reductions in a heating bill come from outside the heating system entirely. Ofgem’s consumer guidance is direct on this point: understanding your tariff and making sure you are on the right one for your circumstances is one of the most significant things a household can do, alongside checking eligibility for energy-saving support schemes and grants that may cover insulation or controls upgrades at reduced or no cost.

When these changes are not enough

These steps reduce waste in an existing system; they do not fix a boiler that is faulty, unsafe, undersized for the home, or so old that parts are no longer available. If you have already tightened up controls, insulation and servicing and the bill or comfort problem persists, that is the point to get a proper survey and compare replacement options on their own merits, rather than as a first resort.

Frequently asked questions

Will turning the thermostat down damage the boiler or system?

No. Room thermostats and TRVs are designed to be adjusted, and running a system at a lower, well-controlled temperature is normal use, not a fault condition.

Is a power flush worth doing on an older system?

It can be, if radiators are cold in patches or the system has never been cleaned, but it is a diagnostic and maintenance decision for a qualified engineer to assess on your specific system, not something to schedule automatically without that assessment.

Should I get a smart thermostat before considering a new boiler?

If your current boiler is safe, reliable and reasonably efficient, adding proper heating controls is usually a lower-cost step to try first. Check compatibility with your existing boiler and wiring before buying, since not every smart thermostat works with every system.

Sources

• The most economical ways to use your central heating – Energy Saving Trust
• Save money on your energy bill – Ofgem

Related guides

Best Boiler Deals is an independent guide. We may earn a fee from some links; this never affects what we write.

A combi boiler heats water directly from the mains, on demand, with no stored hot-water tank – which means shower performance depends on what is coming into the house, not just which boiler is fitted. Two identical boilers can perform very differently in two different properties for exactly this reason.

Pressure and flow rate are different measurements

Worcester Bosch’s own technical guidance is explicit on this point: it is important not to confuse pressure with flow. Pressure is the force pushing the water through the pipe, usually measured in bar; flow rate is the volume of water actually delivered in a given time, usually measured in litres per minute. A property can have adequate pressure but still deliver a disappointing flow rate if the incoming supply pipe is narrow, old, or partially restricted – because flow depends on the size, type and condition of the incoming main, not on pressure alone.

It is also worth knowing that dynamic pressure – the pressure while water is actually running – will always be lower than the static pressure measured with a tap closed. A pressure reading taken with everything off does not tell you what will actually be delivered to a shower while it is running.

Why multiple outlets at once can cause problems

Because a combi boiler heats water on demand rather than from a stored tank, the incoming main has to supply enough flow for hot and cold simultaneously, for every outlet in use at once. On an undersized main, running a washing machine, flushing a toilet or opening another tap while someone is in the shower can genuinely “pinch” flow away from the shower, because the incoming pipe cannot deliver enough water to every point at the same time. This is a common, genuine cause of a shower that performs well most of the time but drops off when other water is being used elsewhere in the house.

What limits the maximum incoming pressure

At the other end of the scale, incoming mains pressure that is too high can also be a problem. Worcester Bosch’s guidance notes that maximum incoming water pressure for a combi boiler is normally 10 bar, and that a pressure-reducing valve may be needed to protect the appliance where mains pressure exceeds what it is designed to handle. This is a reason to have supply pressure and flow properly assessed as part of any combi boiler installation or quote, rather than assumed.

Questions to ask before choosing a combi

When comparing combi boiler quotes, ask the installer to confirm, ideally based on an actual measurement at your property rather than an assumption:

• the measured incoming mains flow rate and dynamic pressure at your property, not just the boiler’s rated maximum output;
• the manufacturer’s stated flow rate for the specific model being quoted, since this varies between models within the same range;
• whether your household’s typical simultaneous demand – for example, two showers used close together, or a shower alongside a washing machine cycle – has been taken into account; and
• whether the existing supply pipework is adequate, or whether an upgrade to the incoming main would be needed to get the flow rate the boiler is capable of delivering.

When a combi may not be the right fit

If a property has a genuinely low mains flow rate that cannot practically be improved, or a household with high simultaneous hot-water demand – several bathrooms used at similar times, for instance – a system boiler with a stored, pressurised hot-water cylinder can deliver strong flow to multiple outlets at once in a way a mains-fed combi cannot, because the cylinder, not the incoming main, is the limiting factor. This is a property-and-household-specific comparison rather than a fixed rule, which is why an on-site assessment matters more than a generic recommendation.

Frequently asked questions

Will a bigger combi boiler fix low water pressure?

Not on its own. The boiler’s output rating describes how much heat it can add to the water passing through it; it cannot deliver more flow than the incoming mains supply is physically able to provide. If flow rate at the property is the limiting factor, a larger boiler does not solve that.

Why does my shower get worse when someone flushes a toilet?

This is the simultaneous-demand issue described above: on some supplies, drawing water at a second outlet reduces what is available to the shower at the same moment, particularly where the incoming main is narrower or older.

Can I add a pump to improve a combi boiler shower?

Sometimes, but this needs proper assessment by a qualified engineer for your specific system and mains supply – not every combi installation is suitable for a booster pump, and any equipment used must be appropriate for use with a mains-fed system. Ask an installer to assess this rather than fitting one speculatively.

Sources

• How could mains water pressure affect my combi boiler? – Worcester Bosch
• Find or check a Gas Safe registered engineer – Gas Safe Register

Related guides

Best Boiler Deals is an independent guide. We may earn a fee from some links; this never affects what we write.