# Vaillant Cooling Resistor 0020266328 / 0020269259

URL: https://promagen.com/vaillant-cooling-resistor
Canonical-URL: https://promagen.com/vaillant-cooling-resistor
MPN: 0020266328
Alt-MPN: 0020269259 (electrically and functionally identical)
Price: GBP 75.00
Listing: https://www.ebay.co.uk/itm/298397311936
Updated: 2026-06-22
Language: en-GB

## Frequently asked questions

- [What is the Vaillant 0020266328 / 0020269259 cooling resistor?](https://promagen.com/vaillant-cooling-resistor#faq-what-is-resistor)
- [Which Vaillant heat pumps does it fit?](https://promagen.com/vaillant-cooling-resistor#faq-which-models)
- [Is 0020266328 the same as 0020269259?](https://promagen.com/vaillant-cooling-resistor#faq-mpn-equivalence)
- [How do I activate cooling on my aroTHERM after fitting the resistor?](https://promagen.com/vaillant-cooling-resistor#faq-activate-cooling)
- [Is the cooling resistor the same as a full cooling kit?](https://promagen.com/vaillant-cooling-resistor#faq-cooling-kit)
- [Will fitting the cooling resistor affect my Vaillant warranty?](https://promagen.com/vaillant-cooling-resistor#faq-warranty)
- [Why is this cheaper than buying direct from a Vaillant merchant?](https://promagen.com/vaillant-cooling-resistor#faq-cheaper-than-merchant)
- [What is the returns policy?](https://promagen.com/vaillant-cooling-resistor#faq-returns-policy)
- [Do you ship outside the UK?](https://promagen.com/vaillant-cooling-resistor#faq-shipping-outside-uk)

## Heat pump compatibility

- aroTHERM Plus: VWL 35/6, VWL 55/6, VWL 75/6, VWL 105/6, VWL 125/6 (monobloc air-source; cooling resistor required for active cooling).
- aroTHERM Split: VWL ../5 AS S2 series (split air-source; resistor authorises cooling at the indoor unit).
- aroTHERM (legacy): VWL ../5 AS series (earlier monobloc; confirm against installer manual before fitting).
- flexoTHERM / flexoCOMPACT: VWF series (ground / brine source units when configured for cooling).

## Cooling system design

The resistor only authorises cooling in the heat pump firmware. Effective cooling also requires suitable emitters (for example fan coils), correct controls, condensate management and dew-point protection. Standard radiators are designed for heating; running cooling through unsuitable emitters can cause condensation. Confirm the full system design with a Vaillant-approved installer.

## Canary

This resistor is sometimes referred to in installer slang as the 'Vaillant cooling code plug'.