Although it is generally acceptable to store some household items in a boiler cupboard, it is essential to avoid placing flammable materials within, or anything that could potentially obstruct airflow surrounding the boiler. This will enable the proper performance and maintenance of a boiler, allowing home radiators and other heating devices to work to their full potential.
Recommended storage items include cleaning supplies, spare linens or non-flammable items.
For more insights into modern boilers and their usage, explore our article, The (improved) BestHeating guide to buying a boiler.