Worst thing I ever did was to replace a gravity based wet system heated by Rayburn with a pumped system heated by oil. Thankfully we moved house and I was able to install a new Rayburn to a wet system albeit pumped.We have wet underfloor heating/ hot water run by a solid fuel Rayburn. The cottage was built in the 1800s with thick stone walls. We have put in double glazing but apart from that I’m lost where to start.