Water-Cooled Air Conditioning Sussex
Fully internal AC systems — no outdoor condenser unit required. Perfect for flats, listed buildings and conservation areas.
Air Conditioning Without an Outdoor Condenser
Many properties across Sussex cannot have a standard split air conditioning system because they can't fit an outdoor condenser unit. Lease restrictions, listed building rules, conservation area planning, or simply no available exterior wall space — these are problems we solve every day.
The solution is a water-cooled internal condenser — a compact unit that sits inside your property, plumbed into the mains cold water supply just like a dishwasher or washing machine. It replaces the outdoor unit entirely, so there's nothing on the outside of your building. No louvres, no grilles, no planning permission needed.
At Ernest Air Cooling, we survey, design and install water-cooled AC systems across Sussex. Wall-mounted or hidden ducted indoor units, single rooms or multi-split systems cooling up to three rooms — all from one condenser hidden in a cupboard.
Key Benefits:
- No outdoor unit or external changes
Nothing on the building exterior — no condenser, no louvres, no grilles
- No planning permission required
Fully internal system — ideal for conservation areas and listed buildings
- Fits in a cupboard or ceiling void
Condenser hides in a hall cupboard, under a counter, or in the ceiling space
- Rooms from 20m² to 50m²
Systems from 2.0kW for bedrooms up to 5.0kW for large open-plan spaces
- Wall-mounted or hidden ducted options
Sleek wall units for retrofit, or fully concealed ducted systems for refurbishments
- Multi-split: cool up to 3 rooms
One condenser, multiple indoor units with independent temperature control
Water-Cooled AC Explained
A standard split system uses an outdoor unit to reject heat into the air. A water-cooled system does the same job using mains water instead — so everything stays inside.
1. Water In
Mains cold water connects to the internal condenser — the same type of connection as a washing machine or dishwasher. A pressostatic valve controls the flow automatically.
2. Heat Exchange
The refrigerant transfers its heat to the water instead of outdoor air. The water exits 20–30°C warmer than it went in and drains away safely. No outdoor unit needed.
3. Cool Air Out
A standard wall-mounted or ducted indoor unit delivers cooled air to your room — identical to what you'd get from a conventional split system. Same comfort, no outdoor unit.
Smart Water Management
Pressostatic water valve — opens only when the system is actively cooling and shuts off completely when it's not
Most water-efficient on the market — the valve regulates flow to the minimum needed for effective heat exchange
Check valve included — prevents backflow into your mains supply, fully compliant with water regulations
Simple plumbing — water in, water out, plus a drain. Same connections as a washing machine
Which Water-Cooled System Is Right for You?
From a single bedroom to three-room whole-flat cooling — there's a water-cooled system to match your property.
| Feature | Wall-Mounted Single Room | Ducted Hidden in Ceiling | Multi-Split (2 rooms) Bi-Split Condenser | Multi-Split (3 rooms) Tri-Split Condenser |
|---|---|---|---|---|
| Best For | Bedrooms, studies, flats | Refurbishments, high-end finish | 2-bed flats, living + bedroom | Whole-flat cooling, 3-bed properties |
| Room Coverage | 20–50m² per unit | 20–50m² per unit | 2 × 25–50m² | 3 × 25–50m² |
| Capacity Range | 2.0–5.0kW | 2.0–5.0kW | 2 × 2.5–8.8kW | 3 × 2.5–8.8kW |
| Indoor Unit Style | Sleek wall unit — visible | Hidden behind ceiling grille | Wall or ducted per room | Wall or ducted per room |
| Condenser Location | Cupboard, utility room, ceiling void | Cupboard, utility room, ceiling void | Cupboard, utility room, ceiling void | Cupboard, utility room, ceiling void |
| Installation Time | 1 day | Multiple visits | 1–2 days | 1–2 days |
| Heat Pump Option | Available | Available | Available | Cooling only |
| Price Fully installed | Free Survey | Free Survey | Free Survey | Free Survey |
Wall-Mounted
Single room · 2.0–5.0kW
Ducted (Hidden)
Single room · 2.0–5.0kW
Multi-Split (2 Rooms)
Bi-split · 2 × 2.5–8.8kW
Multi-Split (3 Rooms)
Tri-split · 3 × 2.5–8.8kW
Why a Free Site Survey?
Every water-cooled installation is unique — we need to assess your water supply pressure, drainage options, condenser placement, and pipework routes before quoting. Our site surveys are completely free and no-obligation.
What's Included in the Price?
Our fully installed price covers the water-cooled condenser, indoor unit(s), all refrigeration pipework, water supply and drain connections, commissioning, and a full handover. F-Gas certified installation throughout.
Properties That Can't Have an Outdoor Unit
If any of these describe your situation, water-cooled AC is your solution
Leasehold Flats & Apartments
Lease prohibits fixing anything to the building exterior? A water-cooled system is entirely internal — nothing for the freeholder or management company to object to.
Listed Buildings (Grade I & II)
External alterations aren't permitted on listed buildings. Everything stays inside — the building's character and appearance are completely preserved.
Conservation Areas
Planning restrictions prevent external changes in conservation areas. With no visible outdoor unit, you get full AC comfort without any planning hurdles.
High-Rise Apartments
No balcony, no ground-level access, no suitable exterior wall. Water-cooled AC works on any floor — all you need is a water supply and a drain.
Converted Properties
Warehouse conversions, barn conversions, loft apartments — often the building structure or shared walls make external units impractical. Water-cooled is the answer.
Home Offices & Studios
Need a temperature-controlled workspace but can't alter the building exterior? Water-cooled AC keeps you productive without any external changes.
How We Install Water-Cooled AC
From survey to cool air — here's exactly what to expect
Free Site Survey
We visit your property to assess the water supply pressure, drainage options, condenser placement, pipework routes, and the best indoor unit position for your room.
System Design
We recommend the right capacity, indoor unit type (wall-mounted or ducted), and condenser model. You'll receive a fixed-price quote with no hidden costs.
Installation
Our F-Gas certified engineers install the condenser, connect the water supply and drain, run refrigeration pipework, and mount the indoor unit. Wall-mount installs: typically 1 day.
Commissioning
We pressure-test the system, charge the refrigerant, test cooling performance, check water flow, and walk you through the controls before we leave.
What Our Clients Say
"Our lease strictly prohibited outdoor units, so we thought air conditioning wasn't an option. Ernest recommended a water-cooled system — the condenser sits in our hall cupboard and the whole flat is cool. Wish we'd done it years ago."
Sarah & Mark Reynolds
Flat owners, Hove
"We run a business from a listed building in Brighton and were told we couldn't have AC. Ernest installed a water-cooled system with zero exterior changes. Our staff and clients have been so much more comfortable through the summer."
Richard Holloway
Business owner, Brighton
Frequently Asked Questions
Common questions about water-cooled air conditioning with no outdoor unit
How does water-cooled AC work without an outdoor unit?
A water-cooled system works like a standard split AC, except the outdoor condenser is replaced by a compact internal unit plumbed into your mains cold water supply. Instead of using outdoor air to remove heat from the refrigerant, cold water flows through the condenser, absorbs the heat, and drains away — similar to how a dishwasher or washing machine connects. A pressostatic water valve opens only when cooling is needed and shuts off automatically, keeping water use to a minimum.
Can I install AC in my flat if the lease prohibits outdoor units?
Yes — this is exactly what water-cooled AC is designed for. Because the entire system is contained inside the property with no external condenser, no louvres, and no changes to the building exterior, it satisfies virtually all lease restrictions. There is nothing visible from outside the building, so freeholders and building management typically have no objection.
How much water does a water-cooled system use?
Water-cooled condensers use a pressostatic water valve that only opens when the system is actively cooling and regulates flow to the minimum needed for effective heat exchange. The valve shuts off completely when the system is not calling for cooling. Modern units are designed to be the most water-efficient on the market. Actual consumption depends on cooling load and ambient conditions, but it is significantly less than many people expect.
Is a water-cooled system as efficient as a normal split AC?
Water-cooled systems deliver comparable cooling performance to standard split systems. The indoor units are identical — the only difference is how the condenser rejects heat (water instead of air). Because water is a more effective heat transfer medium than air, the condenser can actually be very compact and efficient. The trade-off is ongoing water usage, but for properties where an outdoor unit simply isn't possible, a water-cooled system provides genuine, effective air conditioning rather than a compromise.
Where does the internal condenser go?
The water-cooled condenser is compact — a fraction of the size of a standard outdoor unit — and can be installed in a hall cupboard, utility room, under a kitchen counter, inside a built-in wardrobe, or within a ceiling void. It needs a cold water supply connection and a wastewater drain, similar to a washing machine. Refrigeration copper pipework runs from the condenser to the indoor unit, typically through the ceiling void so nothing is visible.
Can one condenser cool multiple rooms?
Yes. Multi-split water-cooled condensers are available that can serve two or three indoor units from a single condenser, with independent temperature control in each room. A bi-split system handles two rooms and a tri-split handles three. This means you can cool a bedroom, living room, and home office from one compact condenser unit hidden in a cupboard.
Do I need planning permission for water-cooled AC?
No. Because the entire system is contained within the property and nothing is fixed to, or visible on, the building exterior, no planning permission is required. This is one of the main advantages for properties in conservation areas or listed buildings where external alterations are restricted.
How long does installation take?
A standard wall-mounted water-cooled installation is typically completed in one day. This includes positioning the condenser, connecting it to the water supply and drain, running the refrigeration pipework, mounting the indoor unit, and commissioning the system. Ducted installations in properties undergoing refurbishment may require multiple visits for first fix, second fix, and commissioning.
What warranty do you offer on water-cooled AC systems?
We offer a 5-year workmanship guarantee on all water-cooled AC installations, covering the indoor unit, internal condenser, and all refrigeration pipework. Manufacturer warranties apply to the equipment itself. We also offer ongoing maintenance plans to keep your system running at peak efficiency — regular servicing helps maximise the lifespan of both the condenser and indoor unit.
Is water-cooled AC suitable for listed buildings and conservation areas?
Absolutely. Water-cooled air conditioning is the ideal solution for listed buildings (Grade I and Grade II) and properties in conservation areas. Everything is contained within the property — no external condenser, no louvres, no grilles, and no penetrations through the building facade. The building's character and appearance are completely preserved while you enjoy full air conditioning comfort inside. Read our guide to AC in listed buildings for more detail.
Related Guides & Advice
AC for Listed Buildings
How to install air conditioning in listed buildings and conservation areas without affecting the exterior.
Why Choose an Authorised Dealer?
What our official partnerships mean for product quality, warranty support, and installation standards.
Single Room Ventilation
Ventilation options for individual rooms — great for pairing with water-cooled AC in sealed apartments.
Ready to Cool Your Property Without an Outdoor Unit?
Whether it's a leasehold flat, a listed building, or a conservation area property, our team will design and install a water-cooled AC system tailored to your space. Book a free site survey today.