What an oil to heat pump conversion actually costs

No single price fits every house. The cost of replacing an oil boiler with an air source heat pump depends on six things, and each one can move the total significantly. Here is what drives the price, and why a written quotation after a survey is the only honest answer.

The only figure already published on this site is a range of £8,000 to £15,000 for a typical oil-to-heat-pump conversion in Scotland. That range is wide because every house is different. The actual price is fixed after a survey and a room-by-room heat loss calculation, never over the phone.

Key facts

Typical range is £8,000 to £15,000 for an oil to heat pump conversion in Scotland.
The price is fixed after a survey and heat loss calculation, never over the phone.
Six factors drive the cost: the unit, radiators, cylinder, insulation, scaffolding, electrical supply.
Scaffolding should be included in the quotation, not charged as an extra.
Interest-free credit up to £30,000, subject to status.

Last updated: 28 October 2026

The six factors that decide the cost

The heat pump itself

A larger unit for a bigger heat load costs more. The size is decided by the room-by-room heat loss calculation, not by the floor area or a rule of thumb. A correctly sized unit is the single biggest factor in whether the system runs efficiently.

Radiator and pipework upgrades

A heat pump runs at a lower flow temperature than an oil boiler. Some rooms will need larger radiators or underfloor heating to deliver enough heat at that lower temperature. If every radiator needs replacing, the cost rises. If most can stay, it does not.

The hot water cylinder

A heat pump does not provide instant hot water like a combi boiler. You need a cylinder, sized for your household. Your existing cylinder may work, or it may need replacing. Pipework may also need adjustment.

Insulation improvements

If the house is poorly insulated, a heat pump will cost a lot to run and may not reach temperature. Loft insulation, wall insulation and draught-proofing may be needed before the heat pump is fitted. These are separate costs, but they are often the difference between a system that works and one that disappoints.

Scaffolding and access

If scaffolding is needed for the outdoor unit or pipework, it should be included in the quotation, not charged as an extra. Ask any installer to confirm this in writing.

The electrical supply

Most air source heat pumps run on a standard single-phase supply, but some larger properties need a three-phase upgrade. If your supply needs upgrading, that is an additional cost from your electricity provider, not the installer.

Why no installer can price it over the phone

A heat pump is sized to the heat loss of the building, not the floor area. Two identical-looking houses can have completely different heat losses because of insulation, glazing, exposure to wind, and ceiling height. Without measuring every room, any price is a guess — and guesses either come back higher later or result in a system that does not heat the house properly.

The written quotation you receive after a survey lists everything: the unit, the cylinder, radiator changes, pipework, scaffolding, and the installation labour. If something is not on the quotation, it is not included — and we will tell you that plainly.

Interest-free credit

Interest-free credit up to £30,000, subject to status.

Interest-free credit of up to £30,000 is available, subject to status and affordability. Terms and conditions apply.

For paying monthly for your heat pump with interest-free credit, more on heat pump heating for rural Scottish homes, or combined boiler and heat pump setups, see our sister sites. Part of the Scottish Energy Efficiency network.

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