District Design: 3 Ways to Reduce Heat Loss in a District Heating Scheme
Keeping heat losses down in a district heating scheme is essential to a scheme’s success. In general, heat loss in a heat network should be kept below 15%, or even better, below 10%. Here are just three ways to reduce heat loss in a district heating scheme.
1. Keep reviewing the design
Continuously reviewing the system’s design criteria and working with manufacturers to get project-specific data for use in calculations rather than general data from data sheets will help avoid over-specification, particularly when it comes to pipe work.
Pipe work runs should be carefully considered to reduce heat loss in a district heating system. Where appropriate, smaller pipe sizes, with their reduced surface area, will reduce heat losses to improve overall efficiency.
Putting into play a strategy for differential pressure control will also make sure a system can adapt according to demand.
2. Go lower with return temperatures
Experience in Denmark has shown us that stored water adds to overall heat losses in district heating schemes. Domestic hot water (DHW) is often stored at 60°C as a matter of course based on outdated and ineffective stored water systems. However, this isn’t always appropriate for district heating systems using Heat Interface Units (HIUs) where DHW is produced via plate heat exchangers.
The Approved Code of Practice L8 suggests that in this scenario, temperatures as low as 50°C can be safely adopted and will help ensure the minimum return temperature requirements of Part L for community heating (Domestic Building Services Compliance Guide, section 6) of less than 40°C for DHW and 50°C for radiator heating are met. Also, opting for HIUs with active return temperature control can help even further.
Effective pipe insulation can have a great impact on energy costs for end users. There is a lack of guidance on this area specifically for district heating systems but my recommendation would be to model the effects of insulation thickness against a whole life cost.
Reducing heat loss is one way to help ensure a district heating system delivers its expected levels of output and performance. There are several ways to do this but reviewing design criteria, lowering return temperatures and improving insulation are definitely some key points to consider.
For more information on our district heating solutions, call us on 0330 123 3004 or visit our local contacts page
Included in its district heating offering, Bosch Commercial and Industrial also provide Heat Interface Units (HIUs) which allow end users simple control over their heating and hot water.
Pete Mills, Commercial Technical Operations Manager at Bosch Commercial and Industrial