SPONSORS INSTALLATION NEWS Electric Water Heating – Boiler Versus Immersion F


or commercial-scale DHW applications, direct immersion heaters are excellent for short-term use, particularly supplying backup for system resiliency. However, if used as the primary heat source in areas with hard water they are highly susceptible to failure due to rapid limescale formation.


Physical, electromagnetic water conditioners do not provide sufficient protection. We’ve seen the evidence of this with organisations which have cut gas from their systems, transitioning to all-electric hot water with DHW buffers heated by immersions. Despite market-leading physical conditioners installed on both the cold inlet and secondary return, every site in hard water reported failures of immersions within four months to a year. Only a salt-based water softener will offer adequate protection, but there is a better, and more cost-effective way of addressing limescale, and that is to use an electric boiler instead. By employing an indirect method of water heating and controlling temperatures the all too common problem of destructive limescale build-up can be effectively eliminated. Working in conjunction with an indirect cylinder to provide DHW in an effectively sealed ‘primary loop’, the expectation is for little to no scale build as the boiler recirculates the same finite amount of water through the heat exchanger. Key to this is maintaining a relatively low (80°C) temperature reducing heating intensity on surfaces that would otherwise accelerate scale formation. The use of an electric boiler supersedes an immersion because it comes complete with a range of controls which would otherwise need to be addressed via the building management system (BMS), which would require costly switchgear and an expert electrical contractor or BMS specialist. Controls offer a variety of options, including


soft start, soft stop; load sharing among internal heating elements, stepped modulation down to 33% of load; control of maximum flow temperature; control of kW output (downrating); overcurrent and overheat protection; weather compensation; plus, fault relay for alarm output to BMS. All of this helps to monitor and maintain the necessary consistency of water temperature and avoid points of high-intensity temperature. Although an electric boiler will use a few


extra Watts for a small pump, it will offer a heating efficiency identical to immersion heaters. However, as scale formation increases immersions will take longer to heat water meaning the boiler will offer greater efficiency over time. Also, as the electric boiler efficiency


is not dependent on flow temperature, it can still provide high primary temperatures that give short cylinder reheat times and easily achieve the required temperatures for regular legionella purging. It is worth noting that the presence of limescale also provides a surface that can help promote legionella growth within the calorifier. You could argue that immersions are easier, cheaper options, that is certainly true if you are installing a 12 kW immersion into a large tank, which will cost you £300 to £700 and, if well maintained, should last. However, if you are trying to add, for example, a 24 kW immersion to a smaller tank, then the complexity of that unit will see the pricing rise quickly to as much as £1500, plus the cylinder will require larger access which also comes at an additional cost. That is also what you would also expect to pay for a 24 kW electric boiler, with all the advantages it brings. With little to no scale build-up, an electric boiler system will exhibit increased reliability and improved response time, whereas immersions will take longer to heat water as scale formation increases around the element hampering its efficiency. The use of multiple heating elements within the boiler also avoids the single point of failure issue seen with immersions, providing built-in redundancy, and when balanced by controls for most efficient use will see system lifespan improve. With less need for descaling maintenance costs


are reduced. Servicing is also easier as the boiler can be wall or cylinder-mounted on either side allowing for flexible installation clearance without the need to withdraw a long immersion heater. There is also no need to drain down the cylinder, which would otherwise interrupt water provision during maintenance or repair. Compared to direct electric immersions, electric boilers offer an EcoDesign-compliant, cost equivalent, simpler to control, ultimately more efficient to run, and easier to maintain system that has a greater lifespan. It should be the technology of choice for any organisation seeking to secure low- carbon DHW in hard water areas.


www.adveco.co RINNAI DECARBONISES PREVALENT NORTH SURREY COMMUNITY HUB R


innai has designed and supplied 5 x 16kW Low-GWP heat pumps plus hybrid cylinders for space heating and hot water delivery to a busy and bustling North Surrey community centre. The centre is used by the local college and houses six large suites, rooms and studios for hire which can be


used for a variety of leisure, educational or local community purposes. For this location Rinnai’s design service employed 5 x HPI Monobloc air source LOW-


GWP heat pumps and electric cylinders as being sufficient to provide all space heating and hot water delivery for the entire building. To take advantage of the free Rinnai design support service today visit https://www. rinnai-uk.co.uk/contact-us/help-me-choose-product Rinnai’s HPI range can allow for up to 7 units to be cascaded together. This LOW-


GWP heat pump technology is designed to satisfy the space heating and hot water demand of a wide range of applications, from domestic to light commercial. The innovative ability of the system to switch between heating, hot water and cooling mode ensures that the HPI has flexibility and durability as standard. A key reason for the selection of Rinnai LOW-GWP heat pumps and hybrid cylinders


is because the models have ultra-low sound capability making them suitable for areas with prohibitive sound legislation. The HPI SL range creates the ideal blend of efficiency and low sound levels ensuring compliance with the most stringent sound standards. Rinnai’s low-gwp heat pumps use R290 refrigerant which has a low global warming potential and maintains an ERP rating of A+++ making this range of commercial heat pumps an economical and environmentally sound choice for future and refurbishment projects. Rinnai’s electric cylinders - The Infinit-E range is an optional three-phase all-electric water heater for predominantly commercial hot water applications. The electric storage water heaters are designed with flexibility in mind as they are fitted with between one and six titanium elements. The KW rating within the Infinit-e range is scalable from 12kw to 72kw ensuring that


our appliances are suitable for a wide variety of applications. The cylinder is manufactured with stainless steel, adding durability and enabling extensive warranties. The use of stainless steel also makes the Infinit-E range lightweight and easily maneuverable when compared to glass-lined variants. The empty weight of the Infinit-e is 54kg maximum. Another added feature is that


all electrical elements can be fitted to a single-phase supply, should site limitations dictate. Each element within the appliance range has its own controllable thermostat with a temperature range of between 49 and 90 degrees Celsius, all elements are fuse protected and there is no need for expensive sacrificial anodes thanks to the tough stainless-steel build. The company’s website, www.rinnai-uk.co.uk, offers customers an interactive and informative platform to view Rinnai’s low carbon domestic and commercial range of technologies which are proven to reduce cost and carbon emissions.


www.rinnaiuk.com 30 BUILDING SERVICES & ENVIRONMENTAL ENGINEER AUGUST 2024 Read the latest at: www.bsee.co.uk If additional information on clean energy technology and appliances is required a FREE brochure can


be requested. Customers can also request a call back at any time to suit their schedules. They will also gain access to a Site Consultation Form and a Carbon Cost Comparison form. All customer services are FREE and found on the “Contact Us” webpage.


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