Vaillant Cooling Plug for Installers: Which Pack to Carry

Two part numbers, one plug

Both numbers are the same blue coding plug on a white two-pin connector. They have been compared side by side — same plug, same connector, same internal stamping. What differs is the pack: 0020269259 comes in Vaillant’s box with “Coding plug, cooling function” on the label, and 0020266328 comes in a Vaillant small-parts bag labelled with the part number only.

UK trade suppliers list 0020269259 as the “Coding plug, cooling-function”. On eBay the bagged 0020266328 costs a fraction of the boxed part.

Which pack for which job

Carry the bagged 0020266328 as van stock: it does the same job for far less, so it is the sensible one to have on hand for the next cooling enquiry.

Buy the boxed 0020269259 when the number matters on paper — the customer’s quote, a warranty record or a specification names 0020269259, or the customer expects to see Vaillant’s cooling label on the box. Many installers will find one of each covers both cases.

What it is listed for

The plug is listed for the aroTHERM Plus range: VWL 35/6, VWL 55/6, VWL 75/6, VWL 105/6 and VWL 125/6. Some aroTHERM Split installations use it too. For earlier aroTHERM units, the newer aroTHERM Plus (v2) and flexoTHERM or flexoCOMPACT ground-source units, check the installer manual for the specific appliance first.

After fitting: what owners end up asking about

Fitting the plug authorises cooling; it does not switch it on. Cooling still has to be enabled at installer level and commissioned, with the minimum cooling flow temperature and dew-point settings configured for the emitters on the job.

Owners on the OpenEnergyMonitor community forum report two settings that caught them out after the plug was fitted: a “cooling technology” setting on the heat pump’s own controller that had to be changed from “no cooling” to “active cooling”, and an energy-supply-company (ESCO) setting left at “Cooling off” that blocked every cooling request. They also report the myVaillant app only showing cooling after being closed and reopened.

• Enable cooling at installer level and set the cooling technology.
• Check the ESCO setting is not blocking cooling.
• Set the minimum cooling flow temperature and dew-point offset for the emitters.
• Confirm the emitters can cool: fan coils, or underfloor with dew-point control — not radiators.
• Show the customer how to switch between heating and cooling on their control.

Ordering

Both part numbers are sold new on eBay by seller boarder895 — 100% positive feedback, on eBay since 2003 — and posted from Birmingham. Set the quantity on the listing if you need more than one. If a job needs the plug quickly, or sent outside the UK, message through eBay before buying and something can be arranged.

Frequently asked questions