Comparison
aroTHERM Plus vs aroTHERM Split for cooling
Monobloc 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.
Updated
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Same blue plug, two packs. Choose the boxed 0020269259, or get the identical 0020266328 for a fraction of the price.
Original Vaillant box, labelled “Coding plug, cooling function”
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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 unit 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. The cooling plug is listed for all five sizes, VWL 35/6 to VWL 125/6.
aroTHERM Split — refrigerant indoors and out
aroTHERM Split divides the system between an outdoor unit (VWL ../5 AS) and an indoor unit, with refrigerant pipework running between the two. Cooling is achieved by reversing the refrigerant cycle.
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, and in both cases an installer must enable and commission it. The cooling plug is listed for aroTHERM Plus; some aroTHERM Split installations use it too, so a Split owner should confirm the requirement for their exact model before ordering.
The practical differences are about installation type — hydronic versus refrigerant pipework — rather than whether cooling is possible.
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 unit |
| Indoor connection | Hydronic (water pipes) | Refrigerant pipework |
| Can cool | Yes — reversible | Yes — reversible |
| Cooling plug | Listed for VWL 35/6 to 125/6 | Some installations — confirm for your model |
| 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, and in both cases cooling must be 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 plug?
The cooling plug (0020266328 / 0020269259) is listed for the aroTHERM Plus range, and some aroTHERM Split installations use it too. Confirm the exact requirement for a Split with a Vaillant-approved installer before ordering.
How do I tell which one I have?
Check the model code on the heat pump data plate: aroTHERM Plus outdoor units carry codes such as VWL 75/6, aroTHERM Split outdoor units codes such as VWL 55/5 AS. A split system also has refrigerant pipework running indoors; a monobloc has water pipes into the home.
Related guides
Ready to buy? Both plugs are on eBay
The plug inside is the same — choose the pack. 0020266328 is the best value; 0020269259 comes boxed and labelled “Coding plug, cooling function”.
Original Vaillant box, labelled “Coding plug, cooling function”
Buy on eBaySold by eBay seller boarder895 · 100% positive feedback · 600+ feedback · on eBay since 2003 · 20+ plugs sold
provenance: sha256:4788e07d0f8fb173… · machine-readable: claims.json · llms.txt