Based on what you have said, I assume the material of construction of the heat exchangers is an austenitic stainless steel like 304 or 316. I am not a fan of putting anything that contains HCl into austenitic stainless steel systems even if it contains corrosion inhibitors. HCl is very corrosive to austenitic stainless steels and should not be in contact with these materials at any concentration. If you continue descaling with this chemical, the risk of corrosion can be minimized by neutralizing any residual HCl. I would suggest rinsing with a dilute base like sodium bicarbonate and then thoroughly flushing the system with water.