Air-source heat pumps
The common outdoor-unit route for wet central-heating systems.
LOW CARBON HEAT
Compare heat pumps for your UK home
A heat pump is a building-and-heating-system decision, not a box purchase. Start with heat loss, emitter temperatures and the quality of the proposed design.
Decision routes
Start with the outcome, not the advert
Air-to-air systems
Room units can heat and cool but normally do not provide hot water.
Ground-source systems
Potentially efficient, with greater groundworks and capital cost.
The CoolCompare check
Four things to compare before committing
Understand heat-pump types, home suitability, running-cost assumptions and installer quotations before choosing a system.
Home heat lossInsulation, glazing and draughts shape the required output.
System temperatureRadiators or underfloor heating must deliver comfort efficiently.
Seasonal performanceCompare stated SCOP with the design conditions behind it.
Installed scopeEquipment, electrics, hot water and commissioning must be explicit.
Source-checked heat-pump models
Compare the equipment—then compare the design
Published figures are useful for shortlisting, but the heat-loss calculation, design flow temperature and installer proposal decide whether a model fits the home.
A strong paper specification at 35°C flow; only meaningful where emitters and heat loss support the design.
A 9–16kW family for larger design loads, with exact capacity selected by a competent heat-loss calculation.
A high-temperature-oriented route worth comparing where an existing radiator system is being assessed.
aroTHERM plus 7kW
- Published output
- 7kW class
- SCOP at 35°C
- 4.36
- SCOP at 55°C
- 3.39
- Refrigerant
- R290 family
Shortlist for a well-designed low-temperature system; compare the exact duty-point output, sound layout and cylinder package.
+ Pros
- Strong published low-temperature SCOP
- R290 refrigerant platform
- Wide output family for designed systems
− Cons
- Efficiency falls as flow temperature rises
- Cylinder, controls and hydraulics add complexity
- Outdoor-unit siting needs acoustic care
! Complaints & watch-outs
- Comfort or high-bill complaints can follow poor sizing, control setup or commissioning rather than an appliance defect.
- Confirm whether the installer or manufacturer owns each type of call-out.
Altherma 3 High Capacity Monobloc
- Nominal classes
- 9 / 11 / 14 / 16kW
- SCOP at 35°C
- 4.69–4.82
- SCOP at 55°C
- 3.37–3.44
- Sound power
- 62dBA published
Makes sense when the calculated load needs a larger unit; do not choose a higher class as a substitute for proper sizing.
+ Pros
- Four high-capacity classes
- A+++ at 35°C published
- Reversible heating/cooling platform
− Cons
- Large outdoor unit
- 62dBA published sound-power figure
- Oversizing can reduce system quality
! Complaints & watch-outs
- Noise concerns need checking against the proposed location and planning calculation.
- Ask for the exact model code: performance varies across the 9–16kW family.
EHS Mono HT Quiet 8kW
- Model class
- 8.0kW
- System type
- Air-to-water monobloc
- Positioning
- High-temperature / quiet
- UK documents
- Installer and service support
Worth a design comparison for retrofit properties, while radiator output, weather compensation and peak heat loss remain decisive.
+ Pros
- Retrofit-oriented high-temperature positioning
- Monobloc architecture
- UK manuals and support route
− Cons
- Higher water temperatures generally reduce efficiency
- Exact control package matters
- Installer experience can vary locally
! Complaints & watch-outs
- Controls, weather compensation and hot-water schedules are common handover friction points across heat-pump systems.
- Get the commissioning settings and design flow temperature in writing.
READ BEFORE SHORTLISTING
Outputs are model-family examples, not a sizing recommendation. SCOP figures depend on test conditions and flow temperature. Ask for the exact model code and design data in every quote.
Side-by-side
Compare the main routes
A quick orientation before you request prices or commit to a contract.
| Decision | Air source | Air-to-air | Ground source |
|---|---|---|---|
| Main job | Wet heating and hot water | Room heating and cooling | Wet heating and hot water |
| Building work | Outdoor unit and heating-system changes | Indoor and outdoor units | Ground array plus plant |
| Best starting evidence | Room-by-room heat loss | Room loads and unit positions | Land survey and heat loss |
| Quote focus | Design temperature and emitters | Air distribution and seasonal data | Groundworks and system design |
Before you buy
Your quote and contract checklist
Save this list and use the same questions with every provider. Comparable inputs produce a more useful comparison.
- 01
Heat-loss calculationAsk for room-by-room outputs and the outdoor design temperature.
- 02
Emitter scheduleRecord proposed radiator or underfloor outputs at the chosen flow temperature.
- 03
Electrical scopeConfirm supply capacity, controls, metering and any upgrade work.
- 04
Commissioning packRequire settings, handover, warranties and maintenance instructions.
Start here
Essential heat pumps guides
Three practical reads that frame the decision without sales pressure.
READINESS01
Is my home heat-pump ready?
Fabric, emitters and electrical checks before requesting quotes.
Read the key answers ↓COSTS02
Heat-pump running costs explained
Why heat demand, efficiency and tariff must be modelled together.
Read the key answers ↓SYSTEMS03
Air source vs air-to-air
Compare wet central heating with room-based heating and cooling.
Read the key answers ↓Plain-English answers
Frequently asked questions
General UK guidance. Product, property, tariff and policy details still need individual verification.
Does a heat pump work in an older home?+
It can, but suitability depends on measured heat loss, emitter sizing, flow temperature and the quality of the design rather than property age alone.
Will I need new radiators?+
Not always. The installer should calculate the output of each existing emitter at the proposed flow temperature and identify only the rooms that need changes.
Can a heat pump cool the house?+
Air-to-air systems commonly heat and cool. Reversible cooling from wet systems depends on equipment, emitters, condensation control and system design.
How should quotes be compared?+
Put heat-loss assumptions, exact equipment, emitter work, electrical work, controls, warranties and commissioning side by side.
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