aroTHERM Plus vs aroTHERM Split for coolingMonobloc vs split — how the two aroTHERM families compare for cooling
The Vaillant aroTHERM range comes in two main forms: aroTHERM plus, a monobloc unit, and aroTHERM split, which uses refrigerant pipework between outdoor and indoor parts. Both are reversible and can cool. This page compares them so you can see how the choice affects a cooling setup.
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aroTHERM plus — the monobloc
aroTHERM plus is a monobloc heat pump: the refrigerant circuit stays sealed inside the outdoor unit, and the connection into the home is hydronic — water pipes carrying heating or chilled water to an indoor module and emitters.
Because the refrigerant never leaves the outdoor unit, the indoor side is plumbing rather than refrigerant work. Vaillant presents aroTHERM plus as a heating, hot-water and cooling platform; check the installer manual for the cooling-capable variants and what each needs.
aroTHERM split — refrigerant indoors and out
aroTHERM split divides the system between an outdoor unit and an indoor hydraulic station, with refrigerant pipework running between the two. The cooling function is achieved by reversing the refrigerant cycle, and the indoor station can display cooling energy and efficiency figures.
Because refrigerant pipework is part of the installation, a split system involves additional commissioning steps and UK F-gas obligations. It can suit sites where refrigerant piping is already the preferred architecture.
What this means for cooling
Both families are reversible and can run active cooling. In both cases the cooling resistor authorises cooling, and an installer must enable and commission it. The practical differences are about installation type — hydronic versus refrigerant pipework — rather than whether cooling is possible.
Whichever you have, confirm the exact cooling requirements for your model with a Vaillant-approved installer, as variants within each family differ.
A side-by-side comparison. Both can cool; the differences are in how the system is built and commissioned.
| Aspect | aroTHERM plus | aroTHERM split |
|---|---|---|
| Type | Monobloc | Split |
| Refrigerant location | Sealed in the outdoor unit | Outdoor unit and indoor station |
| Indoor connection | Hydronic (water pipes) | Refrigerant pipework |
| Can cool | Yes — reversible | Yes — reversible |
| Cooling authorisation | Cooling resistor + installer activation | Cooling resistor + installer activation |
| Installation note | No site refrigerant work | F-gas work; more commissioning |
Frequently asked questions
Can both aroTHERM plus and aroTHERM split cool?
Yes. Both families are reversible and support active cooling. In both cases cooling must be authorised with the cooling resistor and enabled by an installer.
Is one better for cooling than the other?
Neither is inherently better at cooling. The difference is the installation type — monobloc hydronic versus split refrigerant pipework — not cooling capability. The right choice depends on your site and existing system.
Do both use the same cooling resistor?
The cooling coding resistor sold here authorises cooling on compatible aroTHERM and VWL units. Always confirm the exact requirement for your specific model with a Vaillant-approved installer.
How do I tell which one I have?
Check the model name on the heat pump data plate. A split system also has an indoor hydraulic station and refrigerant pipework; a monobloc has water pipes into the home. If unsure, an installer can identify it.