Floorplans. Air duct diagrams. Heat pump specifications. Most people in the market for a new heating system probably don't want to think about this level of detail.
But, perhaps surprisingly, some do want to think about those things. In extreme depth.
Every day, roughly 150 new users sign up to an app called Cool Calc, which works out the heat requirements of properties in the US.
Just over one third of those new users are not tradespeople but private homeowners, says founder and chief executive Bill Fiore.
When choosing a heating system, people can find themselves bombarded with information â how powerful a heat pump do they need, for example? It isn't always easy to take a tradesperson at their word.