The Listed Places of Worship Grant Scheme is a VAT reclaim scheme, not a capital grant. It lets you claim back the VAT on eligible repairs and alterations to listed places of worship in the UK. If your heating installation counts as an alteration to a listed building (and most do), you can reclaim the 20% VAT, which on a £15,000 installation means £3,000 back.
The scheme covers labour and materials for work that would normally need listed building consent or, for Church of England churches, faculty approval. Routine maintenance and like-for-like replacements are excluded, but upgrading from gas to electric or installing a new radiant system typically qualifies.
Claims are made after the work is complete. Keep all invoices, make sure your contractor breaks out the VAT clearly, and submit the claim through the scheme's online portal. Processing usually takes a few weeks. It is free money that many churches miss simply because nobody told them about it.