cold make up supply

[Deleted User]

when would it be correct to pipe the cold make up supply water directly into the boiler return?; type of boiler? make of boiler? special piping? etc

Unknown

We pipe it into the return

almost exclusively . All types of boilers . While purging , the makeup water is forced to the bottom of the boiler and any air carried with it is slowed down to be vented out . And you get the side benefit of purging the system with hot water .

[Deleted User]

hmm, i sorta followed that

but can you say it in another way. because all of the piping diagrams that i find show the cold supply tied into the air separator or somewhere there abouts. and my thoughts were that it's done that way so that you'd never be able to dump cold water into a hot boiler; ie, so that the boiler, in the case of a cast iron, wouldn't be shocked/cracked. and, in the event of a failure of the prv, the boiler/return would get flooded with cold water and very shocked/cracked. ?