Abstract: A boiler assembly comprising a removable boiler unit (2) detachably connectable to a manifold unit (3), the arrangement being such that the manifold unit provides the boiler unit, in use, with a connection interface (7) to a pipework system, wherein boiler unit comprises a rear boiler unit section and a base boiler unit section (6), and there is provided a support structure (40) which extends from said base section to said rear section.