Hello. I have a 5 ton McQuay geothermal heat pump. It is installed as an open loop system using water from my well. The water is loaded with iron and based on the thickness of iron deposited on the inside of all of the system components I expect that the heat exchanger is also coated internally. The system has a cupro-nickel coil. Last fall I flushed the coil out with IronOut that I bought at Home Depot. It appeared to work very well. I mentioned it to the refrigeration guy that checked my system at the end of the heating system and he said that he didn't think that I should use IronOut but that I should use weak muratic acid. Is it safe to use IronOut? It is certainly easier to work with than acid.
The McQuay unit heated my home great all last winter and the AC unit has worked great this hot summer. I'm quite satisfied so far.