Next time you hear "heat pumps don't work in old buildings" remember this:
Ireland’s oldest surviving purpose-built residential building has a heat pump providing all of its heating.
Built between 1699 and 1702 the Rubrics Building is the oldest building within Trinity College Dublin. It's a Protected Structure and Recorded Monument.
https://www.irishbuildinganddesignawards.com/building-project-of-the-year/the-rubrics-building