The cost of adding cooling to a heat pumpThe realistic cost layers — from the resistor to a full cooling circuit
Adding active cooling to a Vaillant heat pump has several cost layers. The coding resistor is the smallest of them at £47.50. The larger costs are the cooling-capable emitters, controls, drainage and installation. This page sets out the realistic layers so you can plan. All figures here are indicative typical ranges, not quotes — your actual cost depends on how many rooms you want cooled and your site.
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The resistor is the small part of the bill
The coding resistor itself costs £47.50 for a genuine Vaillant part. It is what authorises cooling, and it is a fixed, known cost.
Everything else is the system that actually delivers cooling. Those costs are larger and more variable, because they depend on your home rather than on a single component. It helps to think of the project in layers.
The cost layers explained
A cooling upgrade is usually made up of five layers: the coding resistor, the cooling-capable emitters, the controls, the drainage and pipework, and the installation labour. The table below sets out indicative ranges for each.
The emitter layer is normally the biggest. Hydronic fan coil units are typically in the region of £700–£1,500 or more per room unit before installation, according to the research behind this site. Multiply that by the number of rooms you want cooled and the emitter layer alone can be substantial.
Why the total varies so much
There is no single price for "adding cooling" because two homes are rarely alike. The main variables are the number of rooms to be cooled, how easy it is to route the extra pipework and condensate drains, whether new controls or zoning modules are needed, and how much making-good and boxing-in the job involves.
A single-room cooling upgrade is a much smaller project than cooling a whole house. The only reliable figure is a written quote from a Vaillant-approved installer who has surveyed your property.
Treat figures as indicative, not quotes
The cost bands on this page are indicative ranges drawn from publicly visible component pricing and the research behind this site. They are there to help you set expectations, not to price your job.
Component prices also move over time and vary by supplier and specification. Use the ranges to understand the shape of the cost — small fixed cost for the resistor, larger variable cost for the system — and get a proper quote for the actual numbers.
Indicative cost layers for an active-cooling upgrade. These are typical ranges to aid planning — not quotes. Whole-project cost depends on room count and site.
| Cost layer | What it covers | Indicative cost |
|---|---|---|
| Coding resistor | Genuine Vaillant cooling resistor (0020266328 / 0020269259) | £47.50 — fixed |
| Cooling emitters | Hydronic fan coil units, one or more per room cooled | Around £700–£1,500+ per room unit (indicative) |
| Controls | Vaillant system control such as sensoCOMFORT, plus zoning modules where needed | Varies with system — quote required |
| Drainage and pipework | Condensate trays and trapped drains, extra pipe runs, insulation | Site-dependent — quote required |
| Installation | Survey, fitting, commissioning and making-good | Site-dependent — quote required |
Frequently asked questions
How much does it cost to add cooling overall?
There is no single figure. The resistor is £47.50; the wider upgrade depends on how many rooms you cool and your site. Indicative emitter costs alone are around £700–£1,500+ per room unit before installation. Get a written quote for your home.
Are the figures on this page quotes?
No. They are indicative typical ranges to help you plan. Actual prices vary by supplier, specification, room count and the difficulty of the installation. Only a surveyed quote is reliable.
What is the cheapest way to add cooling?
Cooling fewer rooms costs less, because the emitter layer scales with the number of room units. Even so, the resistor plus a single cooling-capable fan coil with drainage and controls is a real installation project, not a token cost.
Can I budget for just the resistor?
Only if your heat pump already has cooling-capable emitters, drainage and controls in place. For most homes the resistor is one line on a larger bill, because the system also has to be able to deliver cooling.
What about running costs?
This page covers the cost of installing cooling, not running it. Active cooling uses the compressor, so it draws electricity when in use, though a heat pump remains an efficient way to move heat.