Compatibility
Which Vaillant heat pumps need a cooling resistor?
Listed for aroTHERM Plus — and what to check for every other model
The Vaillant cooling plug (cooling resistor) unlocks cooling on cooling-capable Vaillant heat pumps that are supplied without it. It is listed for the aroTHERM Plus range, VWL 35/6 to VWL 125/6, and some aroTHERM Split installations use it too. For any other model, the only reliable check is your model code and a Vaillant-approved installer.
Updated
Buy the Vaillant cooling plug on eBay
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”
Buy on eBaySold by eBay seller boarder895 · 100% positive feedback · 600+ feedback · on eBay since 2003 · 20+ plugs sold
aroTHERM Plus — the models it is listed for
The cooling plug is listed for all five aroTHERM Plus sizes: VWL 35/6 (3.5 kW), VWL 55/6 (5 kW), VWL 75/6 (7 kW), VWL 105/6 (10 kW) and VWL 125/6 (12 kW). These are monobloc air-source heat pumps that Vaillant presents as a heating, hot-water and cooling platform — the cooling hardware is built in, and is unlocked rather than added.
Vaillant’s aroTHERM Plus product information says that S2 units can have cooling activated later with an optional accessory. Separately, Vaillant’s UK trade suppliers list part 0020269259 as the “Coding plug, cooling-function”. The same plug is also sold as 0020266328.
aroTHERM Split
The aroTHERM Split pairs an outdoor unit (VWL ../5 AS) with an indoor unit, and it is reversible. Some aroTHERM Split installations use the cooling plug, so a Split owner should confirm the requirement for their exact model with a Vaillant-approved installer before ordering.
Earlier aroTHERM and ground-source models
For aroTHERM monobloc models from before aroTHERM Plus, the cooling plug is not confirmed. Check the installer manual for your exact model and serial number before ordering any part.
flexoTHERM and flexoCOMPACT ground-source heat pumps, sold under VWF codes, set up cooling differently — Vaillant’s documentation describes active and passive cooling arrangements that depend on the heat source. Do not assume a ground-source unit needs the cooling plug; check your installer manual or ask a Vaillant-approved installer first.
- Air-source heat pumps use VWL model codes.
- Ground-source heat pumps use VWF model codes.
- The model code and serial number are on the unit’s data plate.
A family-level overview. Confirm your exact model with a Vaillant-approved installer before ordering if it is not on the aroTHERM Plus list.
| Family | Models | Cooling plug |
|---|---|---|
| aroTHERM Plus | VWL 35/6, 55/6, 75/6, 105/6, 125/6 | Listed for all five sizes |
| aroTHERM Split | VWL ../5 AS with an indoor unit | Some installations — confirm for your model |
| Earlier aroTHERM | Monobloc models before aroTHERM Plus | Not confirmed — check the installer manual |
| flexoTHERM / flexoCOMPACT | VWF ground-source | Cooling set up differently — check first |
Frequently asked questions
How do I know if my model needs the cooling plug?
Find your model code on the unit’s data plate. If it is an aroTHERM Plus — VWL 35/6, 55/6, 75/6, 105/6 or 125/6 — the plug is listed for it. For anything else, ask a Vaillant-approved installer to confirm before ordering.
Do both aroTHERM Plus and aroTHERM Split use it?
The plug is listed for the aroTHERM Plus range. Some aroTHERM Split installations use it too, so confirm the requirement for a Split with an installer.
What about an older aroTHERM?
For aroTHERM models from before aroTHERM Plus, the cooling plug is not confirmed. Check the installer manual for your exact model and serial number before ordering any part.
Do flexoTHERM ground-source units need it?
Don’t assume so. Vaillant’s ground-source heat pumps set up cooling differently, depending on the heat source. Check your installer manual and confirm with a Vaillant-approved installer before buying anything.
Is the part the same for every aroTHERM Plus size?
Yes — the same plug is listed for all five sizes. It is sold as 0020269259 (boxed, labelled for cooling) and as the identical 0020266328 (Vaillant small-parts bag).
What about the newer aroTHERM Plus (v2)?
The eBay listings name the VWL 35/6 to 125/6 models. One UK trade supplier, Midsummer Wholesale, lists 0020269259 as compatible with both older and newer (v2) aroTHERM Plus models, but that is their statement, not something verified here. If you have a newer unit, check its installer manual or ask a Vaillant-approved installer before ordering.
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: sha256:8736206b8e6fb570… · machine-readable: claims.json · llms.txt