Vaillant Cooling Plug for aroTHERM Plus Heat Pumps

It is the genuine Vaillant coding plug — also called the cooling resistor, code plug, cooling chip, cooling dongle or coding key — that unlocks cooling on a Vaillant aroTHERM Plus heat pump supplied without it. Once it is fitted, the heat pump enters Authorised Cooling Mode, so an installer can switch cooling on in the settings. Vaillant sells it boxed as 0020269259, labelled “Coding plug, cooling function”. The same plug also comes in a Vaillant small-parts bag as part 0020266328.

Yes — the plug inside is the same. I sell both and have compared them side by side: same blue plug, same connector, same internal stamping — what this site calls Verified Dual-MPN. The difference is the packaging: 0020269259 comes boxed and labelled “Coding plug, cooling function”, while 0020266328 comes in a Vaillant small-parts bag labelled only with its part number. Either one does the job.

You are paying for the box and the label, not a different plug. The 0020269259 comes in Vaillant’s own box with “Coding plug, cooling function” printed on it. The 0020266328 is the same plug in a plain Vaillant bag, and costs a fraction of the price.

If your installer, quote or paperwork names 0020269259 — or you want Vaillant’s cooling label on the box — choose the boxed 0020269259. If you just need the plug that unlocks cooling, the 0020266328 does exactly the same job for much less.

It is listed for the aroTHERM Plus range: VWL 35/6, VWL 55/6, VWL 75/6, VWL 105/6 and VWL 125/6 (3.5 to 12 kW). Some aroTHERM Split installations use it too. For any other model — the newer aroTHERM Plus (v2), earlier aroTHERM units, and flexoTHERM or flexoCOMPACT ground-source units — check your installer manual or ask a Vaillant-approved installer before ordering.

Fitting the plug is only half the job. Once it is connected, a Vaillant-approved installer enters the heat pump’s installer menu and enables the cooling function. The plug puts the firmware into Authorised Cooling Mode; the installer setting actually switches cooling on. Use a Vaillant-approved installer for both steps.

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

Don’t assume so. The plug is listed for aroTHERM Plus air-source heat pumps. Vaillant’s ground-source heat pumps set up cooling differently, so check your unit’s installer manual or ask a Vaillant-approved installer before buying anything.

Yes. Both are genuine Vaillant parts, new and unused, in Vaillant’s own packaging — the 0020269259 in its box, and the 0020266328 in a Vaillant small-parts bag with the part number on the label.

Yes — get in touch before you buy. Message me through eBay (use “Contact seller” on either listing) with where it needs to go and by when, and something can be arranged. The standard postage options and prices are shown on each listing.

On eBay. I sell both as boarder895 — 100% positive feedback, on eBay since 2003. You pay through eBay’s checkout, postage and returns are set out on each listing, and your purchase is covered by the eBay Money Back Guarantee. This website doesn’t take orders or payments.