Scenario: Heat bank with oil fired boiler, option of additional gravity connections. Multi-fuel stove to be installed separately. Thoughts: Get a stove with a boiler and install a gravity circuit to the heat bank as well. Might serve as a back up in the event of boiler maintenance, could even be the main heat source if it's in regular use. Question(s): What is the optimum fall for the 28mm feed and return pipework? The heat bank will be on the floor above the stove. Will there be wasted circulation if the stove is not in use? Any other observations welcome.