Heat pump running costs in Ireland: do you actually save against oil or gas?

It depends mostly on two things you can check in a minute: how old your boiler is, and which electricity tariff you would be on. Against an older oil boiler the saving is clear. Against a modern condensing gas boiler on a standard 24-hour tariff, a heat pump barely wins at 2026 prices.

Prices checked 18 October 2026. Every figure below comes from SEAI or the suppliers' published tariffs, linked where it appears. Your own bills are a better starting point than any average, and the free check lets you type them in.

The prices behind the sums

Electricity costs about three and a half times as much per kWh as oil or gas. A heat pump wins only because it delivers about three units of heat for each unit of electricity, so the two nearly cancel out. That is why small changes in efficiency or tariff flip the answer.

How the sum works

1. How much heat your house uses. Take what you spend on fuel in a year, divide by the fuel price to get kWh of fuel, then multiply by your boiler's efficiency. SEAI puts older, non-condensing boilers at 55% to 75% and condensing boilers at 85% to 97%; we use 70% and 88%.
2. How much electricity a heat pump needs for that heat. Divide by the seasonal performance factor (SPF). An SEAI-funded trial in Irish homes measured an average of 3.08, ranging from 2.84 to 3.36; we use 2.8 to 3.5 and show the result as a range.
3. Price that electricity at your tariff.

How much electricity does a heat pump use?

Roughly a third of the heat it delivers. A house that spends €1,800 a year on oil with an older boiler is using about 10,300 kWh of heat; a heat pump would need about 2,950 to 3,700 kWh of electricity a year to deliver it, on top of whatever the house already uses. Expect your electricity use to rise by about that much while the oil or gas bill disappears. A bigger or leakier house uses more heat, and so more electricity, in proportion.

Worked examples: a €1,800 a year fuel bill

All for the same €1,800 annual spend. The gas rows assume you stop paying for gas altogether; if you keep gas for cooking, take about €145 a year off the saving for the standing charge.

Two things stand out. First, the boiler you are replacing matters more than the fuel: an older boiler wastes about a third of its fuel, and a heat pump recovers that. Second, the tariff is worth €100 to €150 a year on its own. Anyone installing a heat pump should be on a day/night or smart tariff, and ideally scheduling hot water for the night rate.

If you have a condensing boiler and a standard tariff, the honest answer is that the fuel saving alone is not the reason to switch. Comfort, getting off oil deliveries, a boiler that is due for replacement anyway, and the grant covering most of the price are the reasons; our check lets you enter the cost of the boiler you would otherwise need, which changes the payback a lot.

Payback

Take SEAI's median installed cost for a semi-detached house, €16,741, less the full €14,500 grant: €2,241 out of pocket. Against an older oil boiler on a standard tariff that pays back in roughly 4 to 11 years; against an older gas boiler, 3 to 5 years; against a condensing gas boiler on a standard tariff, anywhere from 5 to over 30 years. The ranges are wide because the measured efficiency range is wide, and because a few hundred euro of saving a year is very sensitive to prices. Nobody can honestly give you one number.

Why some heat pump bills are high

The trial average of 3.08 is what well-installed systems achieve. Bills go wrong when the system is run like a boiler: flow temperature set high, radiators too small for the lower temperature so the heat pump works harder, the system switched off and on instead of running steadily, or a house that was never insulated. None of that is visible in a quote, which is why a heat loss survey and sized radiators matter more than the brand of heat pump. The quote checklist covers what to look for.