As temperatures soared through the summer of 2026, intense heat waves turned upstairs bedrooms into stifling, sleep-depriving zones. For many modern properties lacking proper ventilation and suffering from airtight construction, sleepless nights became the norm.

The situation was unbearable for Lee Mitchell – homeowner, heating professional and owner of Green Dragon Heating near Neath, South Wales. Upstairs in his family’s modern three-bedroom detached house in a quiet cul-de-sac, thermal imaging recorded indoor temperatures hitting 31°C. Lee was forced to sleep in the downstairs conservatory, the coolest spot in the house, and even spent one night outside on a sun lounger!

Opening windows risked noise and indoor air pollution, and standard room fans were insufficient for the upper level. Lee needed a high-performance indoor climate control solution that could integrate seamlessly without disrupting his existing Vaillant ecoTec 28 condensing combi boiler set up for radiator heating and hot water. While traditional wall-mounted air conditioning cassettes were considered for the bedrooms, the family rejected them due to their visual intrusion.

Having recently completed fully certified training to become a Unico System Specialist Installer Partner (USP), Lee saw a prime opportunity to test the company’s Small Duct High Velocity (SDHV) HVAC system in his own home. If successful, it would serve as a strong proof-of-concept for Green Dragon Heating’s diverse client base, which includes housing associations. “I went into the project with an open mind and we have been delighted with the results,” says Lee.

The property features a traditional brick-and-block cavity wall construction. Because the downstairs boiler and radiators handled heating reliably, Lee wanted to leave the ground floor untouched. “The beauty of the Unico System installation upstairs is that it is independent of the downstairs heating,” says Lee. “There has been zero disruption to the efficient existing heating system and we haven’t had to consider a massive, whole-house HVAC renovation to incorporate air conditioning.”

In August 2026, Lee personally installed the system, pairing it with an externally wall-mounted Daikin Perfera 6kW split-system air conditioner and heat pump, positioned above the garage. The Unico System’s modular, small-duct design allowed for a retrofit into the upper floor with zero structural changes.

The core Unico 1218 Series Air Handling Unit, featuring a blower, heating/cooling modules and refrigerant coil, was tucked away in the loft. A compact main plenum feeds 12 small-diameter, sound-attenuating flexible supply ducts routed across joists and ceiling voids. Discreet ceiling outlets distribute conditioned air into the rooms: two round white outlets in each children’s bedroom, three in the main bedroom and five across the large landing area, while the air intake is hidden in a landing airing cupboard. “Installation was very straightforward and I received good backup from Unico,” Lee comments. Beyond solving the heat issue, the low operational noise of the Unico System has protected the family’s sleep. “Even when the fan was working at 100%, you could scarcely hear anything,” says Lee.

The Unico System is capable of delivering both renewable cooling and heating, allowing Lee to switch mode for the approaching colder season while keeping existing upstairs radiators turned off. System control is managed via Bluetooth through a mobile app interfaced with a Daikin indoor room controller linked to the heat pump.

The set-up also offers future flexibility, as Lee can easily drop additional flexible ducting through an existing cupboard to extend the Unico installation to the ground floor. “Over the summer, the existing landing outlets provided some cooling downstairs anyway,” he notes. “At some stage we can dispense with the combi boiler, use the heat pump, and go completely green step-by-step.” The intrinsic value of the installation is this ability to extend it the future by upgrade it by adding an air purification module if needed. It is a system for today and the future.

This project highlights how homeowners can avoid all-or-nothing upgrades. By pairing a traditional downstairs combi boiler and radiator set-up with an upstairs Unico SDHV system and heat pump, properties preserve robust reliability downstairs and whisper-quiet climate comfort upstairs.

Green Dragon Heating specialises in designing and installing full ranges of air conditioning, heating, and plumbing systems across South Wales. “Professional AC installations providing high efficiency, improved air quality, and year-round comfort are in higher demand than ever,” says Lee. “As a Unico Specialist Partner (USP), we have the expertise in SDHV systems to offer sustainable cooling without expected disruptions. My home is a showcase for the technology. Over the coming months, we will record indoor temperatures and run cycles to calculate costs per kWh, highlighting comparative running costs and potential savings to our prospective Green Dragon customers.”

By deploying a high-velocity, small-duct setup alongside a heat pump, homeowners can achieve zoned, whisper-quiet climate control without disrupting existing infrastructure or aesthetics.