One of the first questions homeowners ask us is whether they need a monobloc or a split system. Both pull heat from the outside air, both work well below freezing, and both qualify for the £7,500 Boiler Upgrade Scheme grant. The difference sits in where the refrigerant circuit lives and what that means for your property.
How a Monobloc Heat Pump Works
A monobloc unit holds the entire refrigerant circuit, including the compressor and heat exchanger, inside one outdoor casing. Water, rather than refrigerant, travels into your home to feed radiators, underfloor heating and your hot water cylinder.
Because the refrigerant is sealed at the factory, installation is quicker and takes up almost no space indoors. There is no requirement for F Gas refrigerant work on site, which keeps the job straightforward.
How a Split System Heat Pump Works
A split system divides the components between an outdoor unit and an indoor unit, with refrigerant pipework running between the two. The heat exchanger sits inside the property instead of outside.
This layout calls for an F Gas registered engineer to connect and charge the refrigerant lines, along with indoor space for the internal unit. Splits are sometimes chosen for exposed locations, as there is no water pipework running outdoors that could freeze in a hard winter.
Comparing the Two Options
- Indoor space: monobloc needs the least, while a split requires room for an internal unit
- Installation: monobloc is generally faster and involves fewer trades on site
- Servicing: monobloc units are simpler to isolate and service outdoors
- Frost protection: monobloc systems depend on correct glycol levels and pipe insulation
- Grant eligibility: both qualify when fitted by an MCS certified installer
Which Systems Do We Install?
We design and install monobloc heat pumps from Grant and Vaillant, the two manufacturers we work with for domestic and light commercial projects. Between the Grant Aerona³, the Grant Aerona 290 and the Vaillant aroTHERM plus, outputs run from 3.5kW up to 17kW, which covers everything from a small flat to a large detached house.
The R290 models use a natural refrigerant with a global warming potential of 3, deliver flow temperatures of up to 75°C and carry Quiet Mark accreditation for low noise.
Talk to Us Before You Decide
The right system depends on your heat loss figures, your outdoor space and the condition of your existing pipework. We assess all of this during a site survey, so the recommendation you receive suits your property rather than a general rule.
Book a free consultation or call us on 0208 936 7639 to talk through your options.
