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Air conditioning
Coventry University Technology Park with no alternative but a total system replacement. After a 12-week project, the Enterprise
Centre building’s entire air conditioning installation was replaced with a VRV IV heat recovery system from Daikin UK. And it has sparked a rolling project to replace R22 systems in a technology makeover elsewhere in the park. The three-storey Enterprise Centre is one
of several buildings in the park, accommodating start-up and small technology businesses. Overall, the park enables tenants to work among like-minded people and gives them access to meeting rooms, high-speed communications and the wider academic community. When problems hit the Enterprise Centre’s system, consultants Pick Everard and Daikin installer Envirotech Climate Control were called in. Richard Cobb, an associate at Pick Everard, says: “We were commissioned to plan and design the replacement of a Daikin R22 refrigerant ducted air conditioning system at the Enterprise Centre within Coventry University’s city centre campus. We facilitated the installation to accommodate new LV switchgear for external condenser compounds. “The original systems were defunct and no longer maintained, meaning they need to be replaced. We phased works to limit disruption to the occupants within a live environment; all work within the building was conducted out of hours, either at night or weekends. “This is a rolling programme for the rest of the site to replace the R22
refrigerants completely. Once finished the result will be buildings that are significantly more energy efficient and fully compliant with building regulations.” Envirotech Climate Control director Brett McKay says the centre now has nine
VRV IV heat recovery condensers in a compound at the rear of the building. He says: “There are three systems – one for each floor – giving the building a total of 136hp. Indoors, there are medium static pressure ducted fan coil units throughout. We also installed Daikin heat reclaim VAM units to provide energy efficient ventilation.” To give tenants some flexibility with the temperature of their offices, the fan coil units and the ventilation units are individually controlled via Daikin wired remote controllers. Overall, the systems are controlled with a Daikin i-Touch Manager with a Bacnet gateway interface to link with a building management system. The installation, in a fully operational building, posed some problems for
Envirotech. Brett McKay says: “We worked on one floor at a time, entirely out of office hours so as not to disturb the tenants. With a team of 10 on the project, we were able to complete the project on schedule.” Technology Park manager Jane Rawlings-Purcell held several meetings with
the Envirotech project team at the start of the project so that issues could be identified. She says: “My expectations were exceeded and the result was a well- designed system that was seamlessly installed without any hitches. It made a pleasant change to work with a very professional team that actually listened to our needs and managed the job faultlessly.” Daikin VRV IV systems use R410a
refrigerant that, although it is the subject of a long-term phase-down in the move towards lower GWP alternatives, is expected to be still in widespread use well after 2035.
www.heatingandventilating.net
Tech makeover for Techno Park A
fter nearly two decades’ excellent service, failure of an air conditioning system based on R22 refrigerant left
ViewPoint When does a boiler condense? I
n order to deliver optimum benefits, condensing boilers need to be seen as part of a system, rather than a standalone item of plant. Ross
Anderson of ICOM explains. In April 2007, the UK became the first country in the EU to mandate the sale and fitting of condensing boilers in domestic installations (new build or refurbishment of old heating systems). In September 2015 the Energy-Related Products and Energy Labelling Directives resulted in a requirement that commercial boilers (70-400kW input) also had to be condensing. However, there’s more to harnessing the benefits of condensing than
simply installing a condensing boiler. For maximum efficiency, every aspect of the system has to be designed for condensing. For example, to make a boiler operate in condensing mode the heating system must be designed to allow sufficient heat dissipation, thus lowering the return temperature to below the condensing (dew) point. For natural gas this is circa 55°C. Unfortunately, old heating systems in the UK were designed around high flow/return temperatures (e.g. 82/71°C) and high flow rates. A condensing boiler installed onto this sort of system, therefore, is unlikely to condense. Most boilers today are installed in systems with circulating pumps which deliver a 20°C temperature rise across the boiler. The benefit of this is that with a 50°C (or lower) return temperature, the boiler can condense and give a sufficient flow temperature of 70°C (or lower) for heating radiators. However, unless the installed heat emitters have been replaced and sized based on the new operating conditions (70/50°C), then the room comfort condition will not be achieved, the lower return temperature will not be produced and condensing will not occur. Nevertheless, even in this non-condensing mode the condensing boiler system efficiency will be higher than that of a traditional boiler, due to the significantly lower flue gas temperatures achieved, compared to a traditional boiler (120°C ~ 180°C). So in this mode of operation, there will be a system efficiency gain, with condensing boilers delivering circa ~3%+ increased efficiency when in non-condensing mode. This increases to ~15%+ when in condensing mode and, as explained above, is influenced by the return temperature. So it’s not just a case of replacing the boiler; the whole system needs to be considered in order to optimise the system performance. Pumps, controls, pipework and heat emitters play their part in building an efficient system and should all be considered in the design. In redesigning the system, careful consideration needs to be given to
the location of the boiler and flue runs, to ensure that the flue system works at lower flue temperatures with less buoyancy. Installations using a vertical flue system require re-calculation and for horizontal flues, consideration should be given to minimising the impact of the resultant flue gas plume generated by a condensing boiler at the flue terminal. Details of flue systems and terminal locations can be found in manufacturers’ instructions, BS6644 or IGE/UP/10 4th edition. Summary
Condensing boilers have the potential to significantly reduce energy consumption and emissions in a wide range of applications. The key to gaining maximum advantage is to consider the whole system, not just the boiler.
ICOM Energy Association ICOM September 2018 25
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