Vaillant Cooling Resistor for aroTHERM & VWL Heat Pumps

It is the Vaillant coding resistor (often called a "code plug") that puts a Vaillant aroTHERM or VWL heat pump into Authorised Cooling Mode — the firmware state in which cooling becomes selectable in the installer menu. Without the resistor fitted, the heat pump operates in heating and hot-water mode only. Vaillant supplies it under part number 0020266328, and under the functionally identical and interchangeable part 0020269259.

It is used across the aroTHERM Plus VWL ../5 and ../6 series, the aroTHERM Split VWL series, and the flexoTHERM / flexoCOMPACT range when configured for active cooling. Always check your unit’s model-specific Vaillant installer manual to confirm the correct resistor part number before ordering.

Yes — we call this Verified Dual-MPN. Vaillant has shipped the cooling resistor under both part numbers (0020266328 and 0020269259), and we hold physical evidence the two numbers identify the same component. They are functionally and electrically identical and interchangeable. The part supplied here works in any installation that calls for either number.

Fitting the resistor is only half the job. Once it is connected, a Vaillant-approved installer must enter the heat pump’s installer menu and enable the cooling function in the settings. The resistor puts the firmware into Authorised Cooling Mode; the installer-side setting actually switches it on. We strongly recommend involving a Vaillant-approved installer for both steps.

No. Radiators are heating-only emitters — too little surface area to absorb useful heat, and any cold radiator would just collect condensation. To actually deliver cooling, the building side needs a Fan-Coil Cooling Loop: a closed chilled-water circuit feeding fan-coil units that catch condensate in a built-in tray. The work to add that, alongside the existing heating system, is what we call a Cooling-Ready Retrofit. Ask a Vaillant-approved installer to quote one before assuming cooling will work.

Yes — it is the same genuine OEM Vaillant component, supplied new in sealed factory packaging. This is surplus stock sold direct, so there is no difference in the part itself.

Yes. This is a genuine OEM Vaillant component, supplied new in sealed Vaillant factory packaging with the part number printed on the bag.

The resistor is dispatched from the UK on a tracked Royal Mail service, worldwide. Postage prices and estimated delivery times for your country are shown on the eBay listing and confirmed at eBay checkout. Orders are dispatched within 1–2 working days of payment clearing, and the tracking number is uploaded to your eBay order. Need it faster? Next-day UK delivery can usually be arranged on request — message us before ordering and we’ll sort it.

We accept returns worldwide. Let us know within 30 days of delivery; the resistor must be unused and in its original Vaillant packaging. The buyer is responsible for return postage. This is in addition to your statutory 14-day right to cancel under the UK Consumer Contracts Regulations 2013 for online purchases. See the Returns page for the full policy.

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