Heat-pump or fixed-AC brand
Vaillant
Vaillant supplies air-source and multi-source heat pumps in the UK, with matched indoor hydraulic units, cylinders and controls.
Vaillant’s current UK heat-pump catalogue covers air-source equipment and the indoor multi-source flexoTHERM platform. A Vaillant system can also include a hydraulic module, integrated uniTOWER, separate uniSTOR cylinder, sensoCOMFORT control and myVAILLANT connect gateway.
These components have separate product codes and functions. Recording each one avoids treating a cylinder, controller or source module as though it established the heat pump’s output or certification.
aroTHERM air-source ranges
aroTHERM plus is a monobloc air-to-water range using R290 in the outdoor unit. The established UK page lists 3.5, 5, 7, 10 and 12 kW capacity classes, up to 75°C flow temperature and operation down to -25°C. A separate new-generation aroTHERM plus page is also live, so the full VWL code and technical sheet are needed to distinguish the supplied generation.
aroTHERM split is a refrigerant-split system with separate outdoor and wall-mounted indoor units. Its current page lists 3.5, 5, 7, 10 and 12 kW classes. The established schedule uses R410A, so monobloc R290 siting or service instructions do not apply to it.
flexoTHERM source modules
flexoTHERM is an indoor brine-to-water heat pump. It operates as a ground-source system with a ground loop, as a water-source system with a fluoCOLLECT heat exchanger or as an air-source system with an aroCOLLECT air-to-brine module.
Current UK pages cover 230 V models in 5, 8 and 11 kW classes and 400 V models in 5, 8, 11, 15 and 19 kW classes, although the homeowner page highlights the five 400 V sizes. The heat-source module and complete code are part of the system definition.
Indoor equipment, certification and guarantees
uniTOWER integrates a cylinder and hydraulic components for aroTHERM plus. Its current technical page gives 188 litres of actual storage and refers to it as the 190 litre product. uniSTOR is the separate-cylinder route, with current heat-pump models from 150 to 800 litres and pre-plumbed forms from 150 to 300 litres.
The MCS (Microgeneration Certification Scheme) Product Directory held current aroTHERM plus, aroTHERM split and flexoTHERM records on 23 July 2026. Some dated certification periods were due to end later in 2026 or 2027, so the live exact record remains necessary.
Vaillant’s current product pages state a two-year standard guarantee for aroTHERM plus, aroTHERM split and flexoTHERM, with routes up to seven years subject to installer, registration and Vaillant-cylinder conditions. Those conditions should be checked against the product and certificate rather than treating seven years as automatic.
Related entries
Current manufacturer and register links
Reference type
Heat-pump or fixed-AC brand
UK status
Active in current research
Last reviewed
23 Jul 2026
Product range
The live UK heat-pump list includes two aroTHERM plus generations, aroTHERM split, flexoTHERM and aroSTOR, alongside uniTOWER and uniSTOR system equipment.
Linked model pages
Vaillant ranges in the catalogue
Model pages list product families and register-listed model codes for this brand. They do not replace manufacturer datasheets or installer design documents.