30 Unitary Air Conditioning
There are times when split systems aren’t the best choice for projects, and where packaged condenserless, twin-duct heat pump units will more readily meet the end customer’s needs. Paul Greenough, air conditioning product manager with Powrmatic, explains.
HERE IS NO doubt there are many occasions where a unitary air conditioner is the ideal way to control comfort conditions within a small space, such as an office or hotel room. Usually the first option that is considered is a traditional split system but this isn’t always the most appropriate choice – often because the outdoor units are considered unsightly or do not comply with planning regulations.
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In the past an alternative has been a packaged through-the-wall unit. However these old-style designs no longer satisfy prevailing energy regulations such as the Energy-related Products (ErP) Directive. A more recent entry to the market is the condenserless twin-duct heat pump air conditioner with a packaged monobloc design and considerably better energy performance and lower noise levels compared to the traditional through-the- wall unit.
ACR News May 2015
These packaged units certainly provide specifiers and installers with a viable alternative to split systems but it is important to be aware of the differences between units and select the one that best meets the needs of each project. Clearly all of these units also share key characteristics. For example, they all have a monobloc design that avoids the need for an external condenser unit mounted outside the building. This is achieved by using a twin duct connection to the outside through an external wall so that the only elements visible from the outside are two small grilles. Ideally, these external grilles should only be open when the unit is operating and closed when it is turned off to help conserve energy and prevent ingress of dust, noise and insects. Another benefit of these newer condenserless units is that they are much quieter than traditional through-the-wall units. With new designs that incorporate
high levels of acoustic insulation, as well as quieter compressors and fans, it is now possible to achieve noise levels as low as 32dB at one metre on low speed (41dB on high-speed). These are ideal for use in applications where noise levels are critical, such as in hotel rooms or libraries. Energy performance is another important criterion and although condenserless units will not typically offer the same efficiency of the split system, the newest designs certainly come close. They are certainly able to provide Class A efficiency in line with new energy labelling regulations. Use of the latest generation of DC fans will also make a significant contribution to energy efficiency. When considering the energy
performance of a condenserless heat pump unit it is clearly important to consider the heating function as well as cooling. Indeed, in many of the applications of this condenserless technology, such as in hotel
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