Small duct solution

Widely used in the United States, small duct heating, ventilation and cooling is now available in the UK thanks to a partnership between US manufacturer Unico Systems and UK distributor and training provider Bell Plumbing Supplies. Richard Soper from Unico Systems highlights the key benefits. 

Air conditioning and ventilation has always been seen as a ‘nice to have’ in the UK, thanks to our temperate climate, but with a series of record summers and increasingly unpredictable weather patterns many people now view climate control as an essential requirement. Air conditioning is more widespread in our cars and public spaces, so people are now seeking that same level of comfort in their homes. 

The problem to date is that the air conditioning systems available in the UK have traditionally been developed for commercial applications with little or no regard for homes. Often those refurbing or developing properties have had to rely on large, unsightly outlets that are entirely unrelated to heating systems. The US is used to much larger variances in temperature, meaning that domestic ventilation and air conditioning is often installed as standard. One of the main solutions to this is small duct heating, ventilation and air conditioning. Small duct systems provide both heating and cooling through small, discreet outlets, similar to recessed spotlights.

How it works
To enable air conditioning as well as heating, the best option is to connect the system to a reversible heat pump, which will absorb geothermal energy or warm and cool air from the outside which is passed through the specially designed heating and cooling coil. In an air source heat pump, low-level heat within the external air is transferred to the refrigerant through evaporation. This is then passed through to the indoor evaporator which releases the absorbed heat over the heating coil. The cooling cycle is the reverse of this cycle, where the indoor heat is absorbed by the refrigerant and transferred to the outdoor heat exchanger, the cooling of the air condenses the refrigerant which is then passed over the cooling coil.

The system will then redistribute throughout the home to create the required temperature. The design of small duct systems means that they remove up to 30% more humidity than conventional air conditioning, creating a more comfortable environment and contributing to the prevention of damp and mould. 

While traditional systems distribute air unevenly, small duct heating and cooling delivers even, draft-free cooling and heating. The temperature differential is no greater than 1°C. 

Another benefit is near silent operation. The supply tubing is designed to be as quiet and efficient as possible, with a nylon inner core and insulation that absorbs sound. The air handlers isolate noise and vibration, with closed cell, sound-deadening insulation. As a result, the system is near silent, operating at under 30 decibels.

Easy installation
As you would expect with a small duct system, there isn’t the requirement for large recesses and cavities. The system’s modular air handlers can be easily installed in lofts, utility rooms and cellars. It is important however to carefully consider the location of the central duct and the sound attenuated flexible supply tubes that run through and around the construction of new or existing buildings. Non-invasive installation methods also mean that it’s as applicable to the refurbishment market as well as self-build and new-build projects.

Cooling is now a must-have in UK homes, but for best results systems have to be designed for the specific requirements of domestic properties. Fortunately, the more mature US market can point the way and small duct heating, cooling and ventilation offers an energy-saving solution to meet a variety of requirements, whether for a new build property or a home refurbishment. 

Installer comments

David Jackson, owner of Response Mechanical Services, has more than 40 years-experience installing and maintaining air conditioning systems. He is one of only a very few UK engineers that have installed Unico’s small duct systems. Here he discusses some of the key benefits, applications and installation considerations that installers should be aware of:

“As with most air conditioning systems, we’ve tended to see higher demand from commercial and retail facilities than domestic. However, with hotter summers, we’re increasingly finding that people are a lot less willing to suffer in silence at home.

“Some of the features that make a small duct system like Unico so suitable for offices, restaurants and retail spaces are also the ones that homeowners are searching for. How noisy the system will be is often one of the first considerations for developers and specifiers, followed closely behind by whether or not it causes any drafts. Having installed Unico Systems and returned years later to check on them I can say that the sound deadening insulation and aspiration method of heating and cooling really do make a big difference in both of these areas.

“Health is another driver. For one of my customers Unico was specified to achieve lower temperatures and reduced humidity levels to relieve her multiple sclerosis symptoms, while another wanted to reduce allergens to help his son breathe more easily. Given the current situation, demand for improved air quality is only going to increase.

“As an installer one of the main benefits is how flexible the system is. Connected to a heat pump and boiler, all of the heating, ventilation and cooling can be operated by the one system, with the ducting fitting between wall cavities and floors. The ceiling space needs to be planned out in detail to accommodate the central air handling unit and ducting, which is one of the areas covered in Unico’s training course.”

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