Cooling upgrade
Planning cooling: controls, condensation & cost
Adding cooling well is mostly about getting three things right: managing condensation, setting up the controls, and budgeting realistically. Here is what to plan for.
Condensation and dew point
Cooling chills water, and chilled surfaces can fall below the dew point — the temperature at which moisture in the air condenses. Get this wrong and you get damp pipework, wet floors and, over time, mould.
A properly designed system avoids it in two ways: it never lets the cooling flow temperature drop too low for the room conditions, and it collects any condensation that does form at the fan coils, in trays plumbed to a drain. Condensation management is an engineering task, not an afterthought.
Controls and zoning
Vaillant’s system controls (such as sensoCOMFORT) include dew-point monitoring — they compare the target cooling flow temperature against the current dew point and hold it safely above. They also schedule cooling and can take an external cooling-demand signal.
On larger or mixed systems, Vaillant zoning modules let cooling be directed to some rooms and kept out of others. The right control setup is part of the design — confirm it with your installer rather than assuming default settings will suit your home.
The realistic cost
The cooling plug itself is inexpensive. The cost of a cooling upgrade is in the system around it. The layers to budget for:
- Cooling plug
- The Vaillant coding plug that authorises cooling — tens of pounds on eBay as 0020266328; the boxed 0020269259 costs more for the same plug.
- Fan coil units
- Typically several hundred pounds to £1,500 or more per room unit, depending on size and type (indicative).
- Pipework, valves & drains
- New cooling-branch pipe runs, isolation valves and condensate drainage.
- Controls
- Vaillant system control and zoning modules where the system needs them.
- Installation & commissioning
- Design, fitting, balancing and commissioning by a competent installer.
These are indicative pointers, not a quote. The whole-project cost depends on the number of rooms, pipe routes, drainage and controls — a Vaillant-approved installer can price it for your home.
Use a Vaillant-approved installer
Cooling touches the electrics, the controls and the water side of the system, and the condensation risk is real. Having the plug fitted and cooling designed and commissioned by a Vaillant-approved installer lets them confirm the work sits within your guarantee terms, and makes sure the system is safe and comfortable.
Start with the cooling plug
The smallest line on the budget. Same blue plug, two packs — the boxed 0020269259, or 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