Residential · Air-to-Air
Air-to-Air heat pumps — frequently asked questions
Straight answers to the questions we hear most from homeowners considering Air-to-Air. For anything specific to your home, ask Current — our AI adviser can talk through the right setup for your rooms and how you actually use them.
System types & design
- What's the difference between single split, multi-split, and Multi+?
- Single split is one outdoor unit serving one indoor unit — the simplest setup, suited to a single room or open-plan space. Multi-split is one outdoor unit serving several indoor units (typically 2–6), each controlled independently — the usual choice for several rooms without hot water from the same outdoor unit. Daikin Multi+ is a multi-zone Air-to-Air system that also produces domestic hot water from one outdoor unit, connecting up to four indoor units plus a 120 L or 230 L tank. For most UK homes that only need heating and cooling, multi-split is enough; choose Multi+ when you specifically want rooms and hot water from one outdoor unit.
- What are my options for the indoor unit?
- Wall-mounted is the standard online range and is mounted high on a wall. A ceiling cassette needs suitable ceiling-void depth. A concealed ducted unit supplies air through grilles and usually needs more building work. Floor-standing can suit rooms where wall or ceiling mounting is impractical. They are different product and installation categories: capacity, airflow distribution, noise, access and available models must be checked for the room. We do not assume they perform identically.
- What should I know about the outdoor unit?
- It houses the compressor and does the actual work of extracting or rejecting heat. A single-split has one outdoor unit per indoor unit; multi-split and Multi+ size one outdoor unit for the combined — though rarely simultaneous peak — demand of the connected rooms (and, for Multi+, the hot water tank). Placement matters: it needs unobstructed airflow clearance to run efficiently, and noise, boundary distance, and proximity to bedroom windows should all be considered at the design stage, not worked around afterward.
Refrigerant
- R32 or R290 — does it actually matter which one I get?
- It can matter for the model you are offered, but the refrigerant on its own does not tell you how a system heats in cold weather, how efficient it is, or what it costs to run. R32 has a global warming potential (GWP) of 675. R290 (propane) has a GWP of 3 and is more flammable, so the installation has extra safety requirements. Capacity, efficiency, noise, controls and warranty still depend on the exact model. We tell you which refrigerant the system you are choosing uses.
- Do refrigerant rules mean I should avoid R32?
- No. Rules about placing new equipment on the market are not a ban on using or servicing a system that is already installed, and they are not one UK and EU deadline. In Great Britain, current guidance includes a 2025 restriction on certain new single-split systems below 3 kg with a GWP above 750, with listed exceptions. In the EU, the GWP 150 restriction for small air-to-air split systems is January 2029. January 2027 applies to other specified categories, including small split air-to-water, not to these air-to-air systems as a single rule. Northern Ireland can follow different arrangements from Great Britain. We check the system we offer against the rule that applies to that installation.
Hot water
- Does an Air-to-Air system give me hot water as well as heating and cooling?
- As a rule, no — a pure Air-to-Air system heats and cools air only, and for most manufacturers this is a structural limitation, not something some installers include and others skip. If you want Air-to-Air plus hot water, the usual routes are: a separate Air-to-Water or hot-water-only heat pump running alongside it, retaining or installing a standard immersion or existing water heating solution, or choosing Air-to-Water as your primary system instead if combined hot water and space heating matters more than Air-to-Air's zoned control and cooling. There is one notable exception worth knowing about: Daikin's Multi+ range combines multi-zone Air-to-Air space heating and cooling with domestic hot water from a single outdoor unit — genuinely one system rather than two run alongside each other. It's not yet how the market works as a whole, so ask specifically if this is the configuration you want, rather than assuming any multi-split system offers it.
Brands & reliability
- Is it worth paying more for Daikin or Mitsubishi?
- Pretium currently offers the Daikin and Mitsubishi Electric ranges shown in the catalogue. The right choice depends on the exact capacity, airflow, controls, filtration, finish, matched outdoor unit, warranty and installed scope — not on a generic brand ranking. A higher price does not automatically mean lower noise, better efficiency or more features. Compare the selected models and the quotation rather than treating either manufacturer as one uniform specification.
Control & everyday use
- Does the app actually matter, or is it a gimmick?
- An app can be useful for remote temperature control and scheduling, but functions depend on the exact model, Wi-Fi hardware and manufacturer platform. Wi-Fi is built into the ranges marked that way in our guide; Classic and Ururu Sarara need the stated optional interface or adapter. Energy-use reporting is not assumed for every model. On a multi-split, rooms have their own controls but connected units still share one overall heating or cooling mode.
Health & air quality
- Does Air-to-Air affect indoor air quality, not just temperature?
- Indoor units filter the room air they recirculate. Every range in our guide has a dust filter; extra filtration or active air treatment belongs only to the models identified in the feature guide. Ordinary recirculating units do not bring in outdoor air and do not replace ventilation. Cooling or dry operation can remove excess moisture in suitable conditions. Heating alone does not remove water vapour or solve an underlying condensation or mould problem. Filters need cleaning in accordance with the manufacturer’s instructions.
Maintenance & lifespan
- How long does an Air-to-Air system last, and what maintenance does it need?
- Service life depends on the exact equipment, use, environment, installation and maintenance, so we do not promise one lifespan for every range. Clean the filters at the interval in the manufacturer’s instructions and keep the indoor and outdoor airflow paths clear. The selected product warranty and any servicing conditions are shown with the offer. A professional check follows the manufacturer’s requirements and the condition of the installed system; refrigerant is not routinely topped up in a sealed system without investigating a fault.
- What's actually covered by the warranty?
- The manufacturer’s product warranty and Pretium’s installation or workmanship warranty are separate. Their periods, registration requirements, servicing conditions, exclusions and claim routes are shown in the selected offer and terms. We do not assume a separate longer compressor warranty or apply one model’s warranty to another. Product cover does not replace responsibility for installation workmanship, and workmanship cover does not turn every product fault into an installation claim.
Is it right for my home?
- Why are people increasingly choosing Air-to-Air even when their existing heating works fine?
- Air-to-Water tends to get chosen out of necessity, when a boiler needs replacing. Air-to-Air is increasingly chosen for what it adds that an existing system can't: cooling during hotter summers, independent room-by-room control, or heating for a space — an extension, loft, or garden room — the existing system doesn't reach well. Common cases include home offices needing independent control during work hours, conservatories and garden rooms that are hard to keep comfortable year-round with radiators, loft conversions and extensions poorly served by extending a wet system, and increasingly, bedrooms, for summer sleep comfort.
- Can Air-to-Air work alongside solar panels or an existing heating system?
- It can. Solar generation may contribute while the system is running, but the amount used directly depends on generation, other household demand and when heating or cooling is needed. Air-to-Air can also supplement another heating system or provide selected-room heating and cooling. Controls, tariffs and the intended role of each system should be agreed rather than assuming one generic running-cost result.
- Is Air-to-Air zero-rated for VAT, and can I receive a grant?
- Qualifying fixed reversible air-source heat-pump installations in residential accommodation can receive 0% VAT under the current energy-saving-material rules through 31 March 2027. The catalogue and quotation show the VAT treatment that applies to the offered installation. England and Wales also have a £2,500 Boiler Upgrade Scheme category for eligible residential air-to-air installations under rules effective from 21 July 2026. That is not an automatic discount on a single-room comfort system: the property, full heating-system purpose, eligible technology, MCS installer route and application must all qualify. Pretium must confirm that it can deliver the eligible route before a grant is advertised or deducted. Ask the team for an eligibility assessment and check the current GOV.UK and Ofgem guidance.
Still have a question specific to your home? Ask Current — it can walk through the right system, zone by zone, based on how you actually use your rooms.