LPG (liquefied petroleum gas, primarily propane) is the main alternative to oil heating for UK homes off the gas grid. Around 4 million UK homes have no mains gas connection, and LPG is the closest like-for-like replacement in terms of comfort, system design, and how it integrates with existing radiators and hot water systems.
This guide sets out what a conversion costs in 2026, what drives the price, and how LPG compares with the alternatives on running costs.
What Does an LPG Conversion Involve?
If you’re switching from oil, the boiler itself is likely the main change — both oil and LPG systems use a wet central heating circuit (radiators, pump, expansion vessel) and hot water cylinder. The pipe configuration can often be reused or adapted with minimal replumbing.
If you’re converting from electric storage heaters or a coal system, the job is larger: full radiator installation, pipework throughout the house, a new boiler, and tank installation. This is a full central heating installation, not a simple boiler swap.
A typical LPG conversion involves:
- A new LPG-specific condensing boiler
- An LPG storage tank (either owned or rented from a supplier)
- A regulator, gas meter/governor, and supply pipe from tank to boiler
- Gas Safety Register-certified installation by a CORGI-registered gas engineer (Gas Safe since 2009)
- Commissioning and Building Regulations notification (Part J)
Cost Breakdown
Boiler
LPG-compatible condensing boilers are sold by most mainstream manufacturers (Worcester Bosch, Vaillant, Ideal, Baxi). Combi boilers handle heating and hot water in one unit; system boilers work with a separate cylinder. For properties with multiple bathrooms, a system boiler and unvented cylinder is usually recommended.
| Boiler Type | Supply Cost | Fitted Cost |
|---|---|---|
| LPG combi boiler (24–28 kW) | £900–£1,600 | £1,500–£2,800 |
| LPG system boiler (24–32 kW) | £800–£1,500 | £1,400–£2,600 |
| LPG regular (heat-only) boiler | £700–£1,300 | £1,200–£2,400 |
Fitted costs include gas engineer labour (1–2 days), flue, controls, and commissioning. Excludes tank and tank installation.
LPG Tank
The tank stores propane at your property. You can buy or rent it:
- Rented tank (most common): the supplier owns the tank and you pay an annual rental fee of £60–£120/year. You must buy your gas from that supplier. Tank installation is often free or heavily subsidised on a long-term supply contract.
- Owned tank: you pay £900–£2,500 to buy the tank outright (depending on size) and are then free to get competitive quotes from any LPG supplier.
| Tank Size | Typical Use | Buy Cost | Rental (per year) |
|---|---|---|---|
| 500 litres | Small flat / occasional use | £900–£1,400 | £60–£90 |
| 1,000 litres | 2–3 bed property | £1,100–£1,800 | £80–£100 |
| 1,500 litres | 3–4 bed property | £1,500–£2,200 | £90–£120 |
| 2,700 litres | Large property / high use | £2,000–£2,800 | £100–£150 |
Above-ground tanks must meet UKLPG CoP 1 requirements: minimum 3 m from any building opening and 1 m from any boundary or non-fire-rated structure. Underground tanks have different siting rules and cost more to install (£1,500–£3,500 installation) but may be preferred for aesthetic or planning reasons.
Total Conversion Costs
| Scenario | Estimated Total Cost |
|---|---|
| Oil-to-LPG boiler swap only (tank already present) | £1,400–£2,800 |
| Oil-to-LPG full conversion (new boiler + tank) | £2,500–£5,000 |
| Electric-to-LPG (new CH system + boiler + tank) | £6,000–£14,000 |
| LPG boiler replacement (existing LPG system) | £1,500–£2,800 |
Running Costs in 2026
LPG prices fluctuate with oil markets and exchange rates. As of mid-2026, bulk LPG delivery is priced at approximately 55–75p per litre. Propane has a calorific value of around 25.3 MJ/litre, giving an energy cost of roughly 7–10p per kWh (compared with ~3.5–5p/kWh for mains gas).
For a 3-bedroom home using 16,000 kWh of heat per year through a 90%-efficient condensing boiler:
| Fuel | Approx. Annual Cost (2026) |
|---|---|
| Mains natural gas | £560–£900 |
| LPG (bulk tank) | £1,250–£1,800 |
| Heating oil (kerosene) | £1,000–£1,600 |
| Air source heat pump (with good CoP) | £650–£1,100 |
| Direct electric (storage heaters) | £2,400–£3,500 |
LPG sits between oil and mains gas in running cost. The gap over mains gas is significant; LPG makes most sense where the mains grid is absent, oil infrastructure is already in place (switching tank size or supplier), or where the connection cost to the mains grid (which can be £3,000–£20,000+) makes conversion uneconomical.
Grants and Incentives
As of 2026, there are limited direct grants for LPG specifically:
- Boiler Upgrade Scheme (BUS): This scheme funds air source heat pumps (£7,500), ground source heat pumps (£7,500), and biomass boilers (£5,000) — LPG boilers do not qualify.
- ECO4: Household energy efficiency scheme. LPG boilers may qualify for lower-income households in certain circumstances — check via the Simple Energy Advice service.
- Home Upgrade Grant (HUG2): closed in March 2025; replacement successor schemes are under consultation as of mid-2026.
If you are off-grid and considering a conversion, an air source heat pump may now be the better long-term investment — lower running costs, BUS grant available, and no fuel delivery dependence. The upfront cost is higher (£8,000–£15,000 installed) but payback improves significantly with the grant and current electricity vs LPG prices.
Regulations
All gas work on LPG appliances must be carried out by a Gas Safe registered engineer. You can check registration at gassaferegister.co.uk. LPG counts as a “gas” under the Gas Safety (Installation and Use) Regulations 1998 and requires Building Regulations notification under Part J (combustion appliances). Your engineer should provide a Building Regulations compliance certificate on completion.
Notify your home insurer before converting — changing fuel type is a material fact under most policies.
