SPONSOR CPD PROGRAMME Continuing professional development (CPD) is the regular maintenance, improvement and broadening of your knowledge and skills, to maintain professional competence. It is a requirement of CIBSE and other professional bodies. This Journal CPD programme can be used to meet your CPD requirements. Study the module and answer the questions on the nal page. Each successfully completed module is equivalent to 1.5 hours of CPD. Modules are also available at www.cibsejournal.com/cpd Effective control for condensing gas boiler systems This module looks at key drivers for deploying condensing gas boilers and the control requirements to optimise their performance The boiler is at the heart of most institutional and commercial buildings, to provide the heat for hot water and space heating. This article will consider the key drivers for deploying condensing gas boilers, and explore some of the principal control requirements to ensure effective operation and to minimise environmental impact. Condensing gas boilers, whether fuelled by natural gas, or potentially by hydrogen, are forecast to be the predominant heat source for European buildings for many years to come, as indicated in the data produced for the latest EU Ecodesign review, shown in Figure 1. The minimum performance for a boiler is typically set by codes and standards. Across the EU (including the UK), the Energy-related Products Directive (ErP) leads the regulations of individual member states that, in the Ecodesign regulation EU 813/2013,2 sets efficiency standards for boilers that have an output power of 160,000 Solar combi 140,000 Micro CHP 120,000 Heat pump (electric or gas) 100,000 80,000 60,000 40,000 20,000 Hybrid gas/electric Electric (joule) Oil/gas jet burner condensing Gas condensing Oil/gas jet burner non-condensing Gas non-condensing 0 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 Figure 1: Installed number of heating appliances (in 000s of units) across the 28 states of the EU.1 To provide some context, data from 2016 indicate 95% of appliances have output 70kW less than 400kW. The Medium Combustion Plant Directive (EU 2015/2193) sets limits for appliances over 1MW thermal input up to 50MW. The various UK Building Regulations determine the requirements for 400kW to 1MW (such as the Non-Domestic Building Services Compliance Guide3). Manufacturers indicate this performance based on calculation methods that apply factors providing standardised interpretations of how the boiler will perform seasonally, such as those explained in EU communication 2014/C 207/024 and BS EN 15502-1:2012+ A1:2015.5 Aside from specific installations (in applications with shared chimneys), the requirements of the ErP effectively restrict the majority of non-renewable heating installations to condensing gas boilers. However, the ErP performance metric is based on an idealised set of parameters that are unlikely to wholly reflect the vagaries of real applications. Ensuring that an installation provides expected performance requires appropriate design, which crucially includes a properly considered control strategy and suitably informed end-user operation and maintenance. www.cibsejournal.com July 2019 51 CIBSE July19 pp51-54 CPD v4indd.indd 51 21/06/2019 14:52