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HVAC in schools
Fending off the weather beast
Steven Evans, Potterton Commercial sales director outlines the key considerations for consultants and contractors working on school heating projects
W
ith the big freeze now a distant memory, schools managers will be thinking about scheduling in
heating system upgrades over the summer holidays. Following numerous stories of older systems breaking down when the ‘Beast from the East’ wreaked havoc recently, schools need to ensure they’re always prepared for the extremities of UK weather.
One of the few upsides of the Beast from the East was that in many parts of the country, schools were closed, giving pupils and teachers alike a day to play in the snow. However, for heating engineer and school managers there was no such respite as many spent the time rushing around trying to fix heating failures. With schools under more pressure than ever to stay open during spells of bad weather, a modern, highly efficient heating system should be a must-have. So, what does this look like? First and foremost, schools will be looking for a heating system which will be cost effective to run, not only saving them money on their monthly bills, but also fulfilling their obligations to minimise carbon emissions.
Choosing the most energy efficient
products is straightforward these days, as commercial boilers and water heaters fall under the Energy Labelling Directive (ELD). As part of the Directive, space heaters and combi space heaters of up to 70kW need to have an energy label with a rating ranging from A to G. When used alongside energy efficiency data, these labels can help installers choose between products which have the same energy rating. For primary schools, where hot water will be for hand washing and catering only, a light commercial boiler, such as Potterton Commercial’s Sirius two WH 50kW, and a separate hot water cylinder or direct gas fired water heater, should be adequate to meet the needs of the building users. In a secondary school or college, where hot water demand may also include showers for changing areas, a larger
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output Sirius boiler may be required in addition to a cylinder or water heater. For schools with a larger demand for
heat, it will be worth considering installing more than one boiler, so that they can run in sequence. By setting up a cascade system, the boilers will share the load when they are all operational and should one unit need to be taken offline for repair or maintenance; the remaining units can take the load so there’s no break in heat delivery. Of course, any heating system must be
sized correctly according to the predicted demand of the building to ensure efficiency operation. It has long been recognised that there has been a tendency to oversize boilers, which often comes about due to a natural desire to err on the side of caution to avoid complaints from users about under-performing systems. Thankfully, the flexible and modular nature of a cascade system helps to negate this issue. When replacing an older boiler, it should never be assumed that like-for-like replacement in terms of boiler capacity offers the best solution. Boilers have often
Installing more than one boiler so that they can run in sequence means they will share the load when they are all operational and if one is offline the others can take the load
been specified without considering the building’s heat gains from people, lighting and equipment. Even if such heat gains were taken into account when the original system was sized, changes in use, occupancy, and amount and type of heat-emitting equipment may have occurred over time. Therefore, it is important to size a replacement installation based on the current building requirements, rather than rely on the size of the boiler originally specified. Regular maintenance is key, and this should involve analysing the flue gas to determine the right mixture of gas and air, performing a deep clean of the heat exchanger and testing a water sample to determine pH levels, cleanliness, and detect the presence of contaminants and limescale in the system. Testing and treatment of system water is important as part of the annual service to help maintain boiler efficiency and extend the life of the system. Potterton Commercial’s Sirius wall hung (WH) boilers were recently installed in a new school in Plymouth, specialising in sport, leisure & tourism, hospitality and event management for Years 10 and 12. The contractor specified two 90kW boilers for Plymouth Studio School, and these were fitted in parallel to take 66 per cent of the heat load each.
With a high demand for hot water, the
Schools are under more and more pressure to stay open during poor weather conditions
school’s requirement is served by a separate high efficiency storage water heater. The separation of the heat and hot water plant in this instance helps to save fuel, as during the warmer months when space heating is not required, the Sirius boilers can be taken off line for servicing or turned off completely. While the big freeze may have been hugely disruptive to contractors and school managers, hopefully it has raised the importance of having a reliable, efficient heating system that can stand the test of time. By combining high efficiency with regular servicing, schools can rest assured they’ll be in the best position to fend off any future weather beasts.
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