There are not too many options on manufacturers of low pressure machines these days. Reftec is only one that comes to mind but it’ll cost you. You can have a reclaimer like Hudson come in and recover it for you if you don’t want the investment. You can do it with an Appion if you use fitting adapters to larger hoses but it will take twice as long and it may shorten the life of the Appion for sure.

we use an element and heat the water up to a get positive pressure in the system. valve off the heat exchangers and then circulate with a small pump and an element though any points of connection between the two sides. generally aiming for about 100kpag