Pipes, valves & fittings
inappropriate diversity factors for DHW demand, and over conservative delivery temperatures. Whereas in the past, the use of inappropriate standards has led to significant oversizing, CP1 has cleared up any doubt about diversity standards with guidance to use the Danish DS439. For delivery temperatures, the guidance contained within HSE ACOP L8 for instantaneously heated hot water, should allow designers to work with delivery temperatures as low as 50°C. These two factors have a significant impact on the overall design which would otherwise distort the network size, efficiency, and cost.
Pipe down
With the goal of reducing network heat loss, pipe work runs need to be carefully considered. Poor installation and insulation issues tend to occur on lateral runs, so CP1 suggests breaking up the network into more vertical runs, which are often better insulated and installed. Where appropriate, smaller pipe sizes, with their reduced surface area, give lower heat losses, and whilst there is a knock- on effect to pump energy use, it can still give the best efficiency overall. The target should be to reduce network heat losses to below 15%, with 10% being best practice.
Learn, don’t copy
European and Scandinavian countries lead the way when it comes to well-performing, efficient district
heating schemes, with Denmark using this method to heat the majority of its residential housing. However, when designing heat networks in the UK, we need to consider typical UK operating conditions rather than directly replicating larger projects in other countries. There are many good UK examples of how well designed and operated schemes have significantly reduced users’ bills and the industry must use these as templates to inform future designs. Heat networks should offer the potential for
energy cost reductions over many years, which means a long-term view is necessary. The end user
must be properly considered from the outset, including how they will be metered, billed and pay. Ultimately, the efficiency of a heat network is dependent upon correct design procedures from the outset. The UK has the potential to benefit greatly from district heating schemes, particularly local authorities and housing associations which are often faced with tight budgets and high efficiency targets. Correctly sizing a plant and network according to heat demand, and using smaller pipes and less pipework to keep heat loss in a network to a minimum are two key factors to consider.
Delta Basic - Pressure Boosting Unit
Incorporating
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