Case Study

Off-Grid Oil to Heat Pump Conversion - West Dorset

How a rural cottage replaced expensive oil heating with a heat pump, saving £1,240 annually and eliminating fossil fuel dependence.

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Property Type
4-Bed Detached Cottage
Built 1920s, 145m²
Previous Heating
Oil Boiler
15 years old, 2,500L/year
Total Cost
£13,800
After up to £9,000 BUS grant
Annual Savings
£1,240/year
55% reduction

The Problem: Oil Heating Costs & Uncertainty

Why the Homeowners Wanted Change

  • 💷
    Volatile Oil Prices:

    Annual oil costs ranged from £1,800 (2020) to £3,200 (2022 peak), making budgeting impossible. Average 2023/24: £2,250 for 2,500 litres @ 90p/litre.

  • 🚚
    Large Upfront Payments:

    Minimum 500-litre deliveries (£450-£550) required twice yearly, creating cash flow challenges. Tank monitoring anxiety about running out before next delivery.

  • 🌍
    Environmental Concerns:

    7.5 tonnes CO₂ emissions annually from oil heating. Homeowners wanted to reduce carbon footprint and align with net zero goals.

  • ⚠️
    Aging System Reliability:

    15-year-old boiler requiring increasing repairs (£320 in 2023, £180 in 2024). Oil tank showing minor corrosion, replacement estimated £1,500-£2,000 within 5 years.

  • 🏡
    No Alternative Available:

    Rural West Dorset location, 4 miles from nearest mains gas. Connection cost quoted at £18,000-£25,000 - economically unviable.

Previous Heating Costs (2023/24)

Oil consumption2,500 litres/year
Average oil price90p/litre
Annual oil cost£2,250
Boiler servicing£120
Total annual cost£2,370

The Solution: 12kW Heat Pump System

1

Detailed Heat Loss Assessment

Rural cottage with cavity wall construction, loft insulation (200mm), double glazing throughout. Exposed location on hill required wind exposure adjustment. Total heat demand: 11.5kW @ -3°C design temperature.

Specification: 12kW LG Therma V R32 Monobloc selected for capacity match, excellent cold-weather performance (100% output @ -7°C), and 7-year warranty.
2

Oil Tank Decommissioning

Drained 400 litres remaining oil (sold back to supplier @ 70p/litre, £280 credit). Removed 1,200-litre steel tank, cut and disposed of responsibly. Cleared concrete base, restored garden area with topsoil and turf.

Cost: £450 for tank removal (included in project). Reclaimed 6m² of garden space. Eliminated ongoing tank maintenance/replacement costs.
3

Heating System Conversion

Existing radiator system was well-sized (installed 2015 during renovation). Flushed system thoroughly to remove sludge/deposits. Installed 300L unvented hot water cylinder replacing old vented tank. Added weather compensation controls and smart thermostat.

Advantage: No radiator replacements needed - saved £3,500. Existing system designed for condensing boiler (flow temps 55-60°C) worked perfectly with heat pump at 45-50°C.
4

Outdoor Unit Installation

Positioned on north side of property (previously oil tank location), 25m from nearest neighbour. Concrete base 1.2m × 0.8m with anti-vibration pads. Refrigerant pipes run through external wall into utility room.

Rural advantage: No noise concerns due to distance from neighbors. Unit fully exposed to airflow with excellent performance. Dark green casing selected to blend with rural surroundings.
5

Electrical Upgrade

Existing consumer unit had capacity for heat pump circuit. Installed dedicated 32A MCB and 6mm² supply cable. Upgraded to smart meter (included free by energy supplier) for accurate monitoring.

Future-ready: Switched to Octopus Energy Cosy tariff (12p/kWh off-peak) for 40% cheaper overnight heating. Annual electricity cost reduced further vs standard tariff.

Complete Installation Costs

12kW LG Therma V heat pump£7,200
300L unvented hot water cylinder£1,400
Installation labour (5 days)£5,500
Pipework, fittings, refrigerant£1,800
Smart controls & weather compensation£950
System flush & commissioning£650
Oil tank removal & disposal£450
Electrical work & materials£550
MCS certification & warranties£800
Subtotal£21,300
Less BUS Grant-£9,000
Final Cost to Customer£13,800

12-Month Performance Results

3.9
Actual SCOP
(Seasonal Performance)
£1,010
Annual Energy Cost
(vs £2,250 oil)
11 years
Payback Period
(vs oil replacement)

Annual Running Cost Comparison

Oil heating (2023/24)
2,500L @ 90p/L + £120 servicing
£2,370/year
Heat pump (2025/26)
4,200 kWh @ 24p/kWh average
£1,010/year
Annual Savings
With Octopus Cosy tariff optimization
£1,360/year

Note: Savings increased to £1,360/year after switching to Octopus Cosy tariff (12p/kWh off-peak, 27p peak). Heat pump scheduled to run primarily during off-peak periods.

Environmental Impact

7.5 tonnes
CO₂ emissions (oil heating)
1.2 tonnes
CO₂ emissions (heat pump)
84% reduction
Equivalent to planting 285 trees annually

Homeowner Testimonial - 12 Months Later

"Switching from oil to a heat pump was the best decision we've made for our home. We're saving over £1,200 per year - money we're now investing in other home improvements.

No more anxiety about oil deliveries, price fluctuations, or running out mid-winter. The heat pump just works quietly and efficiently. Our house is warmer and more comfortable than it ever was with oil, and we love knowing our heating is now powered by renewable electricity.

The installation was professional and completed in 5 days as promised. The team explained everything clearly and patiently answered all our questions. One year on, the system has performed flawlessly through summer and winter.

For anyone in rural Dorset still burning oil - make the switch. You'll never look back!"

— David & Emma T., Homeowners, West Dorset

Key Learnings for Off-Grid Properties

✓ Success Factors

  • Oil properties see largest savings (£1,000-£1,500/year typical)
  • Time-of-use tariffs (Octopus Cosy) increase savings by 30-40%
  • Existing well-sized radiators eliminated upgrade costs
  • Rural locations ideal - no neighbor noise concerns
  • LG Therma V excellent cold-weather performance in exposed location

💡 Recommendations

  • Plan installation for spring/summer to use remaining oil through winter
  • Switch to time-of-use electricity tariff immediately after installation
  • Consider solar panels for further running cost reductions
  • Tank removal creates valuable garden space for other uses
  • Payback period improves if oil tank also needs replacement soon

Ready to Replace Your Oil Heating?

We specialize in oil-to-heat pump conversions for rural Dorset properties. Get a free assessment and discover your potential savings.

Call 01202 985350