A quinquennial inspection is a survey of a Church of England church building carried out every five years by a qualified architect or surveyor. It covers the condition of the building fabric, structure and services, and it typically includes a comment on the heating system.
The inspection report is not a heating survey. It will note whether the system is working, whether it shows signs of age or deterioration, and whether it poses any risk to the building. It will not tell you which replacement system to choose or what it will cost.
If your quinquennial report flags the heating as a concern, that is a useful starting point for making the case to your PCC and diocese that work is needed. Some grant applications ask for evidence of need, and a quinquennial recommendation carries weight.