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The question most Scottish homeowners arrive at is simple: should I stick with my gas boiler, or switch to a heat pump?
Sean Hogan · Heat Geek engineer · Updated April 2026 · 10 min read
The question every Scottish homeowner asks before installing a heat pump: what will it actually cost me each month?
Online calculators give national averages. Manufacturer brochures quote ideal-condition figures. Neither tells you what your bill will look like.
This guide walks through real running costs for air source heat pumps using Ofgem’s April–June 2026 price cap, broken down by home size, tariff type, and system setup. It also explains the levers that move your monthly bill, because two identical homes on the same street can have completely different heat pump running costs based on decisions made before and after installation.
A heat pump does not generate heat. It moves it. Outside air contains thermal energy even at low temperatures, and the heat pump uses electricity to extract that energy and transfer it into your home.
The measure that determines your bill is the Coefficient of Performance (COP). A COP of 3.5 means the heat pump produces 3.5 units of heat for every 1 unit of electricity consumed. That is 350% efficiency. A gas boiler operates at around 90%, so for every unit of fuel input, you get 0.9 units of heat back. A heat pump gives you 3.5.
COP changes with conditions. It rises on mild days, falls on cold ones. The figure that matters for your annual bill is the Seasonal Performance Factor (SPF), which averages COP across the heating season. A well-designed system in Scotland typically achieves an SPF of 3.0–3.5. A poorly installed one drops to 2.5 or lower.
Your annual electricity consumption is your home’s heat demand divided by the SPF. That is the number that drives your bill. Everything else in this guide is built on that calculation.
Under the Ofgem April–June 2026 price cap, Scottish electricity sits at approximately 24.71p per kWh. That figure varies slightly between north and south of Scotland, but 24.71p is a reliable working number.
A typical Scottish home needs around 12,000 kWh of heat per year for space heating and hot water. With an SPF of 3.2, the heat pump consumes 3,750 kWh of electricity to produce that heat.
On a standard tariff: 3,750 × £0.2471 = approximately £927 per year, or roughly £77/month averaged across the year.
But the heating load is not flat. You’ll spend roughly £130–£170/month from November to February, and £20–£40/month from June to September. The annual figure smooths out the peaks.
On a smart tariff: With a blended rate of 17p/kWh on a tariff like Octopus Cosy: 3,750 × £0.17 = approximately £638 per year, or £53/month averaged.
With solar PV: For homes with solar and battery storage, a significant portion of the heat pump’s electricity is self-generated. Annual running costs can drop to £200–£400, depending on system size and consumption patterns.
These numbers are for a typical home. Your home is not typical. The next sections show how the figures shift based on what you actually live in.
“What really stood out was the additional guidance Sean provided about how we could improve our home’s insulation and reduce drafts. He explained how making these simple DIY improvements would help lower the heat loss in our home,…
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This is one of the most-searched questions about heat pumps, and the answer depends on the time frame.
Per hour (when running): A typical 7–10 kW heat pump consumes 1–3 kWh per hour of operation, depending on outdoor temperature and how hard the system is working. On a mild day at low flow temperature, that drops to 0.4–0.8 kWh per hour. On the coldest January nights, it can climb to 2.5–3 kWh per hour.
Per day:
Per month:
Per year: A typical 3-bed Scottish home uses 3,500–4,500 kWh of electricity for heating and hot water via a heat pump. Larger homes use 5,000–7,000 kWh. Smaller flats use 2,500–3,500 kWh.
For comparison, the same homes would consume 13,000–20,000 kWh of gas to produce the same heat output. The heat pump uses roughly a third of the energy because it’s moving heat rather than creating it.
The single biggest factor in your monthly bill is your home’s heat demand. Larger and less insulated homes lose more heat and need more energy to stay warm. Here are typical annual running costs at current Scottish prices, assuming a properly installed system with an SPF of 3.2.
1–2 bed flat (heat demand ~7,500 kWh/year):
4 bed detached (heat demand ~16,000 kWh/year):
5+ bed property (heat demand ~20,000 kWh/year):
These figures assume reasonable insulation. A poorly insulated home of the same size will spend 20–40% more. A well-insulated modern build can spend 15–25% less.
The running cost of a 5kW air source heat pump in a smaller property tends to land at the lower end of these ranges. A larger 12 kW unit serving a 5+ bed property pushes toward the upper end. The system size should match the heat demand, not exceed it. Correct sizing is one of the strongest predictors of efficient running.
If you take one thing from this guide, take this. Your tariff choice has a bigger impact on your monthly heat pump bill than almost any other decision you’ll make.
A standard variable tariff charges roughly 24.71p per kWh at all hours. Smart tariffs charge much less during off-peak periods, often 7–15p per kWh, with higher rates during peak hours. Heat pumps work well with these tariffs because they can pre-heat your home and your hot water cylinder during cheap windows, then coast through expensive ones.
Octopus Cosy offers three cheap windows per day: 4–7am, 1–4pm, and 10pm–midnight. Off-peak rate is roughly 13p/kWh, peak rate around 39p/kWh. For a heat pump that does most of its work overnight and at midday, the blended rate often lands at 16–18p/kWh.
Intelligent Octopus Go offers a six-hour cheap overnight window at around 7p/kWh, with a flat rate at other times. Better suited if you also have an EV or run the heat pump heavily overnight.
Octopus Agile changes price every 30 minutes based on the wholesale market. More volatile, but skilled users can drop their blended rate below 14p with active management.
Worked example for a 3-bed semi using 3,750 kWh/year:
That’s a £400/year difference between the worst and best case, on the same heat pump in the same house. It’s also why any installer who hands you a system without discussing tariff strategy is leaving money on your table.
A few practical points. Smart tariffs require a smart meter capable of half-hourly readings. Most modern meters work fine. Some older first-generation smart meters need replacing.
And the heat pump needs to be set up to take advantage of the cheap windows, which usually means scheduling the hot water cylinder boost and adjusting heating schedules. This is part of proper commissioning, not an optional extra.
“We are also grateful for his knowledge and input into adjusting our heat pump and currently our bills are massively reduced.”
Christine C, ★★★★★ Google Review
A heat pump’s only fuel is electricity. If you generate your own electricity, you reduce or eliminate the main running cost.
A typical 4 kW solar PV system in Scotland generates around 3,200–3,800 kWh per year, with most production between March and October. Pair that with a battery and a heat pump, and the maths shifts significantly:
Christine, a customer in Gartcosh, had an existing heat pump that wasn’t optimised and electricity bills hitting £600 in some months. We installed a 10.5 kWp solar array with 20.8 kWh of battery storage and re-optimised the heat pump. Her current monthly electricity bill is £24.79.
For a more typical homeowner adding solar to an existing or planned heat pump, the running cost reduction usually lands at 50–70% in summer months and 20–35% in winter, depending on system size and consumption habits.
The economics of solar in Scotland are no longer subsidised by the Home Energy Scotland loan (that scheme ended in 2023), but a properly sized solar+battery system paired with a heat pump still typically pays back within 8–12 years and continues delivering for 20+ years after that.
If your heat pump is running more expensively than the figures above, the cause is almost always one of the following. None of them are problems with the technology.
Flow temperature set too high. A heat pump running at 35°C flow temperature can achieve a COP above 4. The same system at 55°C drops to a COP of 2.5 or lower. The difference between those two figures is hundreds of pounds per year on the same heating load. Many installations run hot because the radiators were never sized for low-temperature operation, so the installer cranked the flow temperature to compensate. This is the single most common cause of poor heat pump performance in Scotland.
Undersized radiators forcing high flow temperatures. This is the underlying cause of the flow temperature problem. If radiators don’t have enough surface area to deliver heat at low water temperatures, the system can’t run efficiently. A proper radiator sizing assessment identifies which rooms need upgrades and which don’t. Blanket radiator replacement is wasteful. Targeted upgrades transform performance.
Weather compensation disabled or misconfigured. Weather compensation automatically adjusts flow temperature based on outdoor conditions. Mild day, low flow temperature, high efficiency. Cold day, higher flow temperature, lower efficiency but adequate output. Without weather compensation, the system runs at a fixed flow temperature year-round, wasting energy. Many installers skip this step at commissioning. It should always be enabled.
Insulation gaps. Major draughts, missing loft insulation, single-glazed windows in bedrooms: these increase heat demand directly. The heat pump has to work harder, runs longer, and uses more electricity. Targeted insulation improvements (loft, draught-proofing, key windows) pay back faster than expensive whole-house wall insulation.
Wrong tariff. Already covered, but worth restating. A heat pump on a standard tariff is missing 30% of its potential running cost saving. If you have a heat pump and you’re on a standard variable tariff, switching is the single highest-ROI action you can take.
Oversized or undersized system. An oversized heat pump short-cycles, switching on and off rapidly, wasting energy. An undersized one runs flat-out and still can’t keep up, again pushing up the flow temperature. Both result in higher running costs than necessary. A proper heat loss calculation prevents both.
“Sean’s professionalism, technical expertise, and willingness to go the extra mile truly set him apart. He is an absolute superstar, and I can’t recommend Aventus Eco Ltd highly enough for anyone facing similar challenges.”
Sreeram VS, ★★★★★ Google Review
If you already have a heat pump, here are the actions that move the bill, ranked by impact.
1. Switch to a smart tariff. Easiest, fastest, biggest immediate win. Octopus Cosy or Intelligent Go for most households. Expect a 25–35% reduction in running costs.
2. Lower your flow temperature (where the system supports it). If your radiators were sized for low-flow operation, dropping flow temperature from 50°C to 40°C can lift COP by 0.5–1.0, reducing electricity consumption by 15–25%.
3. Enable weather compensation. If it isn’t on, turn it on. If it is on but the curve is poorly set, recalibrate it. A free or low-cost service visit from a competent installer should sort this in under an hour.
4. Pair with solar PV and battery storage. Higher upfront cost, but the long-term running cost reduction is substantial. Particularly worthwhile if you also have an EV or use significant electricity for cooking.
5. Targeted insulation upgrades. Loft top-up, draught-proofing, secondary glazing where needed. Small changes that compound over time.
6. Use the cylinder boost during cheap windows. Schedule the hot water cylinder to reheat during off-peak periods. This alone can save £50–£100/year on a smart tariff.
7. Monitor and adjust. Heat pumps with app monitoring (Vaillant aroTHERM, Panasonic Aquarea) show real-time performance data. Track your COP and electricity consumption. Anomalies usually point to settings drift or a fault that’s worth catching early.
The detailed comparison lives in our heat pump vs gas boiler guide, but here’s the short version.
On a standard electricity tariff, a gas boiler currently runs about £175/year cheaper than a heat pump for a typical 3-bed home. Gas is around 5.64p/kWh, electricity is 24.71p/kWh, and the heat pump’s efficiency advantage doesn’t fully overcome the price ratio.
Switch to a smart tariff and the heat pump moves £75–150/year ahead.
Add solar and the heat pump wins clearly, often by £400+ per year.
For oil boilers, the picture is similar at today’s relatively stable oil prices around 5.8p/kWh. But oil is volatile. In 2022, oil hit 8–10p/kWh and many off-grid Scottish households were paying £1,500–£2,000/year. A heat pump removes that volatility entirely.
For electric boilers, the comparison is one-sided. A heat pump uses roughly a third of the electricity for the same heat output, saving £2,000+/year on a typical home.
Online calculators average across thousands of homes. Your home is one home.
Aventus Eco carries out full heat loss calculations, radiator assessments, and tariff guidance for Scottish homes. We can show you what a heat pump would actually cost to run in your property, what tariff makes the most sense for your usage patterns, and whether solar changes the equation.
If you want real numbers before making a decision, start with the right data.
For a typical 3-bed Scottish home, expect around £77/month on a standard tariff or £53/month on a smart tariff like Octopus Cosy, averaged across the year. Winter months run higher (£130–£170), summer months lower (£20–£40).
In December, January, and February, a typical 3-bed Scottish home using a heat pump spends £130–£170/month on electricity for heating and hot water on a standard tariff. On a smart tariff, that drops to £90–£120/month. Larger homes spend more, well-insulated homes less.
No, when properly installed and on the right tariff. A heat pump on a smart tariff costs roughly the same or less per year than a gas boiler. On a standard tariff, gas is currently slightly cheaper. The difference between an efficient and inefficient heat pump installation can be £300–£500/year.
For a typical Scottish 3-bed home, around £930/year on a standard tariff or £640/year on a smart tariff. Smaller flats run £400–£700/year. Larger 5+ bed homes run £1,000–£1,800/year.
Between 8 and 35 kWh per day depending on the season and outdoor temperature. Mid-winter peaks at 20–35 kWh/day. Shoulder seasons run 8–15 kWh/day. Summer hot water only is 2–5 kWh/day.
A heat pump uses 0.4–3 kWh per hour while running, depending on outdoor temperature and flow temperature. Most heat pumps don’t run continuously, so the average across 24 hours is much lower than the peak.
A 5 kW air source heat pump in a smaller Scottish home (1–2 bed) typically uses 2,000–3,000 kWh of electricity per year. At current prices, that’s £490–£740/year on a standard tariff or £340–£510 on a smart tariff.
A heat pump uses roughly a third of the energy a gas boiler uses for the same heat output. A home that consumes 13,000 kWh of gas per year would consume around 3,750 kWh of electricity with a heat pump. The cost comparison depends on the electricity-to-gas price ratio and your tariff.
Octopus Cosy works for most heat pump households, with cheap windows at 4–7am, 1–4pm, and 10pm–midnight. Intelligent Octopus Go is better if you have an EV or want overnight-heavy operation. Octopus Agile suits households willing to actively manage consumption around half-hourly pricing. The right answer depends on your home and habits.
Yes, significantly. A heat pump scheduled to run during Cosy’s cheap windows typically achieves a blended rate of 16–18p/kWh, compared to 24.71p on a standard tariff. For a typical 3-bed Scottish home, that saves around £290/year.
Yes, substantially. A 4 kW solar PV system paired with battery storage typically reduces heat pump running costs by 50–70% in summer and 20–35% in winter. Larger solar systems with bigger batteries can effectively eliminate running costs for most of the year.
The most common causes are flow temperature set too high, undersized radiators forcing high flow temperatures, weather compensation disabled, insulation gaps, or being on a standard tariff instead of a smart one. Most of these are fixable without replacing equipment.
Switch to a smart tariff (biggest single win), lower your flow temperature where the system supports it, enable weather compensation, schedule hot water reheats during cheap windows, and consider pairing with solar PV. Targeted insulation upgrades also help.
We’ll assess your home, explain your options, and leave you to decide.
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