Quick comparison
| Question | Heat pump | Oil boiler |
|---|---|---|
| Best fit | Low heat loss with suitable emitters and controls | Can deliver high water temperatures in harder-to-retrofit homes |
| Upfront work | Often system-wide: design, cylinder, emitters and electrical work | Can be simpler when replacing like for like |
| Fuel | Electricity | Delivered heating oil plus electricity for pumps and controls |
| Operation | Lower-temperature, longer running, weather compensated | Higher-temperature, usually shorter cycles |
| Storage | Outdoor unit and usually a hot-water cylinder | Boiler, flue and oil tank |
| Support | Current qualifying SEAI heat-pump support can be substantial | Check current scheme rules; a simple fossil replacement is not the decarbonisation route |
Calculate heat demand before fuel cost
Historic oil purchases provide a rough baseline, but tank levels, boiler efficiency and hot-water use create uncertainty. A room-by-room heat-loss calculation also establishes whether emitters can meet demand at lower flow temperatures. Do not compare a heat pump designed for steady whole-house comfort with an oil boiler used for short heating bursts without adjusting the comfort assumption.
When a heat pump case is stronger
- The home has low heat loss or planned fabric work.
- Radiators or underfloor heating can deliver the design load at suitable temperatures.
- There is space for indoor and outdoor equipment.
- The electrical supply and controls can support the design.
- The owner values removing oil deliveries and accepts a different operating pattern.
When the case needs more work
- Rooms already struggle to heat at high boiler temperatures.
- There is no credible fabric or emitter assessment.
- The quotation assumes unexplained seasonal efficiency.
- Hot-water storage, noise, drainage or electrical work is unresolved.
- The installer cannot show who will commission and service the selected system.
Compare lifecycle scenarios
Build a 10- or 15-year comparison with capital cost after confirmed grants, maintenance, realistic annual fuel or electricity, finance cost and likely major replacements. Test more than one energy-price scenario. A single payback number built from today's tariff is not a forecast.
Check whether the house is ready, review complete project costs, or return to the heat-pump hub.