Gas boilers dominate domestic heating in the UK, and significant efficiency improvements have been associated with condensing boilers. However, the potential remains for further efficiency improvement by refining the control, system specification and installation in real dwellings. Dynamic building simulation modelling, including detailed heating system componentry, enables a deeper analysis of boiler underperformance. This paper explores the link between the space heat oversizing of boilers and on/off cycling using dynamic simulation, and their subsequent effect on boiler efficiency and internal temperatures. At plant size ratio (PSR) 8.5 daily cycles numbered over 50, similar to median levels seen in real homes. Simulations show that typical oversizing (PSR >3) significantly increases cycling behaviour and brings an efficiency penalty of 6–9%. There is a clear link between raising PSR, increased cycling and an associated decreased efficiency; however, in the UK, boilers are regularly oversized with respect to space heating, especially combination boilers to cover peak hot water demand. Current legislation and labelling (ErP and SAP) overlook PSR as a determinant of system efficiency, failing to incentivise appropriate sizing. Reducing boiler oversizing through addressing installation practices and certification has the potential to significantly improve efficiency at low cost, decreasing associated carbon emissions.

Practical application: This research provides the basis for a practical and cost effective means of assessing the potential for underperformance of boiler heating systems at the point of installation or refurbishment. By assessing the oversizing of the boiler with respect to space heating, unnecessary cycling and the associated efficiency penalty can be avoided. Plant size ratio, as an indicator of cycling potential, can be implemented in energy performance certificates (EPCs), through the standard assessment procedure (SAP), using existing data. The potential for real carbon savings in the existing boiler stock is considerable, and the findings have wider implications for next generation heating systems.

燃气锅炉在英国的家庭供暖中占主导地位，冷凝锅炉大大提高了效率。但是，通过改进控制，系统规格和在实际住宅中的安装，仍有潜力进一步提高效率。动态建筑仿真建模（包括详细的供热系统组件）可以对锅炉性能不佳进行更深入的分析。本文利用动态模拟探索了锅炉空间热量过大与开关循环之间的联系，以及它们随后对锅炉效率和内部温度的影响。在工厂规模比率（PSR）下，每天有8.5个周期超过50个周期，这与实际房屋中的水平相似。仿真表明，典型的过大尺寸（PSR> 3）会大大增加循环性能，并带来6–9％的效率损失。提高PSR，增加循环次数和相关的降低效率之间有明确的联系；然而，在英国，锅炉通常在空间供暖方面尺寸过大，尤其是组合式锅炉，以满足高峰热水需求。当前的法规和标签（ErP和SAP）忽略了PSR作为系统效率的决定因素，但却未能激励适当的规模。通过解决安装规范和认证来减少锅炉尺寸过大的潜力，可以以低成本显着提高效率，并减少相关的碳排放。当前的法规和标签（ErP和SAP）忽略了PSR作为系统效率的决定因素，但却未能激励适当的规模。通过解决安装规范和认证来减少锅炉尺寸过大的潜力，可以以低成本显着提高效率，并减少相关的碳排放。当前的法规和标签（ErP和SAP）忽略了PSR作为系统效率的决定因素，但却未能激励适当的规模。通过解决安装规范和认证来减少锅炉尺寸过大的潜力，可以以低成本显着提高效率，并减少相关的碳排放。

实际应用：这项研究为评估安装或翻新时锅炉加热系统性能不佳的潜力提供了一种实用且经济高效的方法的基础。通过评估锅炉相对于空间加热的尺寸过大，可以避免不必要的循环以及相关的效率损失。可以使用现有数据通过标准评估程序（SAP）在能源绩效证书（EPC）中实施工厂规模比率，作为循环潜力的指标。现有锅炉存货中真正的碳节省潜力非常可观，其发现对下一代加热系统具有更广泛的意义。