Something like that should have had proper listed building consent. It's a free application to make but will cover your a** in the future.I could understand the need for planning if you need to build the structure to house the system but if installed in an existing building? We had to install a new Flue pipe for our domestic system that was installed inside a listed building. I think we had the listed buildings officer come take a look prior to install and was happy for us to proceed without a planning application, but I don't recall us having any paperwork to that effect.