Heat Pump or Stick With the Boiler? An Honest Look for Irish Homes

Heat Pump or Stick With the Boiler? An Honest Look for Irish Homes

Half the heat pump articles online were written by people selling heat pumps. The other half were written by people who got burned by a botched install and now think the technology doesn't work. Both are wrong. Heat pumps are an excellent solution for the right house and an expensive headache for the wrong one. The trick is knowing which yours is.

The basic difference

A gas or oil boiler burns fuel to make heat. Roughly one unit of energy in, one unit of heat out (modern condensing boilers a touch better). The fuel costs what fuel costs.

A heat pump moves heat from the outside air into your home using electricity. Because it's moving heat rather than making it, you get 3 to 4 units of heat out for every 1 unit of electricity in. That's the magic. It's why heat pumps are talked about — done well, they deliver more heat for less money.

Upfront cost (installed, after SEAI grant)

  • Replacement gas boiler: €2,500 – €4,000
  • Replacement oil boiler: €3,000 – €5,000
  • Air-to-water heat pump: €13,000 – €18,000 installed, minus €6,500 SEAI grant = roughly €6,500 – €11,500 net

Heat pumps are still 2–3x the upfront cost of a like-for-like boiler swap, even after the grant. There's no honest way around that number.

Running cost (typical 3-bed semi using ~15,000 kWh of heat per year)

  • Gas (mains): ~€1,800/year at 2026 unit rates
  • Oil (kerosene): ~€2,100/year
  • LPG: ~€2,800/year — always the most expensive
  • Heat pump (standard electricity tariff): ~€1,400/year
  • Heat pump (smart night-rate tariff like Electric Ireland Home Electric+ or Bord Gáis Home Energy): ~€950–€1,100/year

The smart tariff piece matters hugely. A heat pump on a flat-rate electricity contract is decent. A heat pump on a properly-set-up night tariff with hot-water scheduling is genuinely cheap to run. Most people who say "my bills went through the roof" got installed without anyone advising them on tariffs.

Where heat pumps shine

  • Modern, well-insulated houses (post-2010 builds, or older houses that have had cavity, attic and ideally external insulation done)
  • Homes with underfloor heating or large, modern radiators
  • Homeowners staying long-term (10+ years) — payback is real but slow
  • Properties on oil or LPG (the running-cost saving versus LPG is dramatic)

Where heat pumps struggle

  • Poorly insulated homes (the pump can't keep up on a cold night, runs constantly, costs a fortune)
  • Old houses with small Victorian-era radiators sized for boiler-temperature water
  • Homes on cheap mains gas with no plan to insulate further (the running-cost saving is small)
  • Short-stay owners — you won't break even before you sell

The single most important thing

Get a proper Heat Loss Calculation done by a qualified installer before you commit to a heat pump. SEAI now mandates a "Heat Loss Indicator" of 2.0 or better for grant approval, precisely because so many early heat pump installs were on houses that weren't ready for them. If a contractor will quote you a heat pump without doing this calculation first, walk away.

The honest answer

If your house is already reasonably insulated and you'd otherwise be replacing an oil or LPG boiler, heat pump every time — lower running cost, no fuel deliveries, no annual service contract, government grant covers a meaningful chunk. Payback versus oil is around 7–10 years.

If you're on cheap mains gas and your house is poorly insulated, insulate first, and consider whether a like-for-like efficient gas boiler might be the right interim step while you plan the bigger upgrade. There's no shame in doing things in the right order.

What it costs to get it wrong

A friend-of-a-friend story you'll hear often: "Sure they put in a heat pump and the electricity bill is €400 a month." Almost always one of three things — wrong-sized pump, house not insulated to spec, or no smart tariff. All three are avoidable. None of them mean the technology doesn't work.

CleanEnergy.ie matches you with SEAI-registered heat pump installers in your county who'll do a proper heat loss survey before quoting. Three quotes, no pressure, free for homeowners.