How-to guide
How a Vaillant cooling resistor is fitted
An owner’s overview of where the plug goes and what happens next
If you have ordered a Vaillant cooling plug, it helps to understand how it is fitted — even though the fitting itself is an installer task. In short, the plug goes into a defined coding position in the heat pump wiring, and the controller then recognises that cooling is permitted. This guide is an owner’s overview, not an installation manual: the work itself should be done by a competent, 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”
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What the plug is
The cooling plug — also called the cooling resistor or code plug — is a small blue plug on a white two-pin connector, with a resistor inside. Vaillant sells it boxed as 0020269259, “Coding plug, cooling function”; the same plug also comes in a Vaillant small-parts bag as 0020266328.
It is a passive component. There is nothing to program and no battery or software — its job is simply to present a fixed resistance value to the heat pump controller.
Where it plugs in
The plug fits a defined coding position in the heat pump wiring. The controller has an input that expects a coding plug; when the plug is fitted there, the controller reads its value.
The installer works to your model’s installer manual to find and reach that position safely, with the power isolated.
What happens when it is fitted
Once the plug is in place, the controller reads its value and recognises that cooling is permitted on the appliance. This is what makes the cooling option available in the installer menu.
Fitting the plug does not switch cooling on by itself. It authorises cooling — the controller now knows cooling is allowed — but the function still has to be enabled and commissioned.
Why this is an installer job — and what comes next
Fitting the plug means working safely inside the heat pump. Have a Vaillant-approved installer carry out the work: they can confirm it sits within your guarantee terms and leave the appliance safe.
Fitting must then be followed by enabling cooling in the installer menu, and commissioning. The installer enables the cooling function, configures dew-point and minimum flow settings, and tests the system. Only after that does your heat pump actually cool.
Fitting the plug — and what it still leaves to do
Fitting the plug does
Place the coding plug in the heat pump wiring so the controller recognises cooling is permitted and the cooling option becomes available in the installer menu.
Fitting the plug does not
Switch cooling on. An installer must still enable the cooling function in the menu and commission the system before the heat pump will cool.
Frequently asked questions
Can I fit the cooling plug myself?
Have a Vaillant-approved installer fit it. It means working inside the heat pump, the installer can confirm the work sits within your guarantee terms, and the installer also has to enable cooling at installer level.
Where exactly does the plug go?
It plugs into a defined coding position in the heat pump wiring. The installer works to your model’s installer manual to find it.
Will cooling work as soon as the plug is fitted?
No. Fitting the plug authorises cooling. An installer must still enable the cooling function in the installer menu and commission the system before it will cool.
Does it matter whether I get 0020266328 or 0020269259?
No. They are the same plug in different packaging — 0020269259 boxed and labelled for cooling, 0020266328 in a Vaillant small-parts bag — and either one is fitted in exactly the same way.
Can the plug be removed again?
As a plug-style connector it is physically removable, but removing it withdraws the cooling authorisation. Any change to cooling configuration should be done by a Vaillant-approved installer.
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
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