IBC Technologies Inc. Our wall-mounted condensing boilers convert Natural Gas or Propane into heat with unprecedented efficiency, helping to stretch our precious supply of fossil fuels well into the future. We are dedicated to finding new and better ways to utilize the world’s dwindling energy resources while providing superior comfort, reliability and fuel savings to our customers.DC Series · HC Series · Technical Information Portal · IBC Indirect Water Heaters · Contact Us IBC DC 20-125 Piping Diagram — Heating Help: The Wall The IBC DC is a great little boiler. Yes by going w the combi version you are oversized on the heating side by just about any combi that is worth anything will do that. Would using the HC version of that boiler w/ a 40 gallon indirect work better? Sure. Here is a link to the piping diagrams. The install manuals are available at the website.