The Hydronics Design Tool Kit is a DOS-based software program that automates the design calculations in John Siegenthaler's Modern Hydronic Heating. The software actually consists of 19 modules that do different but very specific tasks. These tasks include expansion tank sizing, room heat-load calculation, pipe sizing calculation and fuel cost estimation. The modules let you use "if-then" simulations to try out different designs. This approach lets you customize the design and use whatever priorities you choose, whether it's efficiency or working with a specific manufacturer's equipment.

Note: This software has now been replaced by a new program called Hydronics Design Studio that operates under the Windows operating system.