OK we all know that refrigerant prices are going thru the roof,shortcuts are going to be made point one is the profit margin refrigerant cannot be marked up ie the client is going to scream!but alas he can scream?but to no avail I had a cold store some months ago two systems both on 404a one system sprung a leak all refrigerant lost emergency situation no 404a so I charged it with 407c with the intention of returning with 404a but the cold store is actually performing well,guess I know adjustments had to be made which I did!,the reason for this post is the end result worked out OK it's clearly marked up but most of the systems I work on/installed on a dual system ie completely separate can cope when one system fails not 100% but close belt and braces approach what's the thinking criticism of course I can take constructive criticism.