Heat Pump vs LPG Boiler: Pros and Cons for Welsh Homes
Last Updated: November 10, 2026
Quick Summary
A heat pump moves heat from outside air into your home using electricity, while an LPG boiler burns propane or butane on site. The fairer comparison is the annual bill for your own home, based on heat demand, seasonal efficiency and current prices, including tank rental and delivery charges. A heat pump suits homes where heat loss has been checked and radiators are sized to match.
Compare annual bills using your own heat demand, not a headline efficiency figure.
Include LPG tank rental, delivery and standing charges in any running cost comparison.
A heat pump typically needs a heat loss calculation before its size and radiators are chosen.
Check official government guidance for current heat pump grant eligibility and amounts.
Book a suitability assessment to see whether a heat pump fits your home.
Is a heat pump right for your Welsh home?
Heatgeek Wales provides MCS-certified air source heat pump surveys and installation across Wales.
Table of Contents
Heat Pump vs LPG Boiler: How the Two Systems Work
If you heat a Welsh home with LPG, the choice in front of you is a real one: keep the boiler you know, or move to a heat pump. Compare other heating alternatives for off-grid homes before you decide. Each system heats water and sends it round your radiators, but they get the heat from very different places. An LPG boiler burns propane or butane in a combustion chamber, so its output is limited by the fuel you buy and the flue it needs. A heat pump, by contrast, moves heat from outside air into your home, using electricity to drive a refrigeration cycle (Install a heat pump).
The practical difference shows up in the outdoor unit, the hot water and the flow temperature. A heat pump usually runs at lower flow temperatures, which suits radiators sized for a boiler only if the room heat loss has been checked. Starting with a heat loss calculation before comparing costs is sensible, because the answer depends on the building as much as the appliance.
Heat Pump Running Costs vs LPG: A Like-for-Like Annual Comparison
Running costs decide most of this comparison, and they are easy to get wrong. The only fair method is to compare the annual bill for the same home, the same heat demand and current LPG and electricity prices, rather than a headline efficiency figure. A heat pump's seasonal performance decides how many units of heat you get per unit of electricity, while LPG cost depends on the price per litre or kilogram and the boiler's efficiency.
Here is a reproducible method you can apply to your own figures. Start with your annual heat demand in kilowatt hours (kWh), which your installer can take from the heat loss calculation or from your past fuel use. Then divide that heat demand by the seasonal performance of each system to get the energy you must buy:
For an LPG boiler, divide heat demand by the boiler's seasonal efficiency (a modern condensing LPG boiler is typically in the low 90s per cent, and older boilers lower). That gives the kWh of propane you need, which you then convert to litres or kilograms using the supplier's calorific value.
For an air source heat pump, divide heat demand by the seasonal coefficient of performance (SCOP). A well-installed system in a well-insulated home commonly achieves a seasonal figure in the region of 3.0 to 3.5, but a poorly set-up system or one running at high flow temperatures can fall well below that.
Multiply each energy figure by the relevant unit price: pence per kWh for electricity, and pence per kWh (or per litre) for LPG. Add standing charges and any LPG tank rental or delivery charges, because these are real annual costs that a boiler quote often hides. The result is a like-for-like annual bill you can defend.
A worked example makes the mechanism clear. Take a home with an annual heat demand of 12,000 kWh. An LPG boiler at 90 per cent seasonal efficiency needs about 13,333 kWh of propane; a heat pump at a seasonal coefficient of performance of 3.2 needs about 3,750 kWh of electricity. At an electricity price of 24p per kWh, the heat pump's energy cost is about £900 a year. At an LPG price of, say, 7p per kWh, the boiler's energy cost is about £933 a year, before tank rental, delivery and standing charges are added. Change either price and the answer moves; that is the point of showing the sum rather than a single figure.
Several factors move the result: your electricity tariff, your LPG delivery price, how well the house holds heat, and how many hours the system runs. The heat pump's running cost relative to LPG depends on the electricity tariff, the LPG price and the system's seasonal performance. Ask your installer for the calculation with stated assumptions, and check that the figures use today's prices. We will not quote a single running cost here, because the answer changes with each property and tariff, but the method above lets you test your own home.
The annual bill comes down to heat demand, seasonal efficiency and unit prices, as the worked example shows.
Input | Example value | Note |
Annual heat demand | 12,000 kWh | From heat loss calculation or past fuel use |
LPG boiler seasonal efficiency | 90 per cent | Modern condensing boilers typically low 90s |
Heat pump seasonal COP | 3.2 | Well-installed systems commonly 3.0 to 3.5 |
Electricity price | 24p per kWh | Example price; check your tariff |
LPG price | 7p per kWh | Example price; check your supplier |
Heat pump energy cost | About £900 a year | Electricity needed multiplied by price |
LPG boiler energy cost | About £933 a year | Before tank rental, delivery and standing charges |
Upfront Costs, Grants and Whole-Life Value
Heat pump installation costs depend on the property and the work involved, so an individual survey gives the most reliable figure. Installation can also involve radiator upgrades, pipework and an outdoor unit site. Several UK grant schemes can reduce the cost of a heat pump, but eligibility rules and grant amounts change, so check the official government guidance before you rely on any figure.
The LPG side of the comparison is often understated. Beyond the boiler itself, an off-grid household typically pays for tank rental or purchase, delivery charges, minimum order quantities and a supplier contract. These costs recur and should be counted in any fair comparison. A boiler replacement quote that ignores them flatters LPG.
Whole-life value means comparing total cost over the system's lifespan, including servicing, the LPG you would have bought, and a replacement date. A boiler and a heat pump typically have different service intervals and lifespans. Compare the two over the same period, and allow for the fact that LPG prices can move sharply.
A practical way to do this is to build a simple table with one column per system and one row per cost category, covering a consistent period such as fifteen years:
Installation: equipment, labour, radiator and pipework changes, and any electrical upgrade.
Fuel: annual LPG or electricity cost from the like-for-like calculation above, multiplied by the period.
LPG infrastructure: tank rental or purchase, delivery, minimum orders and contract fees.
Servicing and repairs: annual service, plus an allowance for component replacement such as a boiler's heat exchanger or a heat pump's compressor.
Replacement: the likely date each system needs replacing within the period.
Watch out: a whole-life comparison that leaves out tank rental, delivery or a mid-period replacement will usually overstate the heat pump's disadvantage, so insist that every recurring cost is included.
Heat Pump Performance in Cold Weather and Hot Water Output
Cold weather is the usual worry, and it is a fair one. An air source heat pump still extracts heat from air at low temperatures, but its output falls as the outside temperature drops, so sizing matters. A correctly sized system with the right flow temperature can keep a home warm through a Welsh winter, though it generally runs for longer periods than a boiler.
Hot water is a separate question. Heat pumps usually store hot water in a cylinder and heat it more slowly than a boiler, so you need enough cylinder capacity for your household. Check how the system handles peak demand, such as showers in the morning, before you commit.
Heat Pump Radiators and Insulation: What Your Home Needs
Radiators and insulation decide how well a heat pump performs. Because heat pumps work at lower flow temperatures, radiators sized for a boiler may not deliver enough heat, and upgrading some of them is often needed. Insulation reduces the heat the system has to replace, which lowers running costs and makes a smaller system workable.
For older stone or solid-walled properties, checking loft and wall insulation first and reviewing radiator sizes room by room is generally sensible. The heat loss survey shows where the gaps are, so it is worth doing before any equipment is chosen.
Switching from an LPG Boiler to a Heat Pump: Installation and Disruption
Switching from LPG involves more than swapping one appliance for another. The LPG tank and supply pipework may remain in place or be removed, and the new system needs a suitable place for the outdoor unit and a cylinder. Installation disruption varies with the property and the amount of pipework or radiator work involved, so ask your installer for a clear programme.
Plan for the LPG supply to stop being used, and confirm with your installer and supplier how any remaining fuel is handled. Commissioning the new system properly is essential, because a poorly set-up heat pump will underperform however well it was specified. Follow this homeowner checklist for commissioning a heat pump to see what to check once it is installed.
Booking Your Heat Pump Suitability Assessment
The fastest way to get a clear answer for your home is a suitability assessment. We will look at your heat loss, radiators, insulation and hot water needs, then set out whether a heat pump fits and what it would involve. If you are ready to book, check that any installer you choose is MCS certified before you arrange a survey. If customers contact us directly we will carry out the survey for free, saving them £250. Get in touch with Heatgeek Wales to arrange your heat pump suitability assessment and see what a heat pump would mean for your home.
Frequently Asked Questions
Is a heat pump cheaper to run than an LPG boiler?
It depends on electricity tariffs, LPG prices, the property's heat demand and how efficiently the heat pump is running. A heat pump typically delivers several units of heat for each unit of electricity, while an LPG boiler converts fuel to heat at a lower ratio. Running costs should be compared using your actual annual LPG consumption, your electricity tariff and a realistic seasonal efficiency figure. A proper survey gives a like-for-like estimate for your home rather than a general figure.
Will a heat pump keep an older or poorly insulated home warm?
A heat pump can heat an older home, but it works best when heat loss is reduced first. Solid walls, draughts and poor loft insulation increase the heat demand, which can push flow temperatures up and reduce efficiency. Improving insulation and checking radiator sizes before installation usually improves results. A home suitability assessment identifies which measures matter most for your property.
Can a heat pump provide hot water as well as an LPG boiler?
Yes, most air source heat pump systems can supply domestic hot water through a dedicated cylinder. Hot water is usually heated to a lower temperature than with an LPG boiler, so the cylinder size and heating schedule need to suit household demand. Your installer should size the cylinder based on how many people live in the home and how much hot water you typically use.
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