New system tripping on low pressure??

[NoNickName]

I'm still waiting to hear how SHR is relevant to service.

Very relevant, and the fact that overcharging or undercharging effects subcooling, it also effects the performance of the evaporator, which in turn effects the evaporating temperature, and in turn increases or reduces the latent heat removal.
But as DTLarca says:

It's like an engineer I recently spoke to regarding a walk-in he looked at for us. I asked him what the subcool and superheat was. He said he did all that superheat and subcool stuff at college 20 years back but he no longer remembers what that all is. He said he has had success repairing systems now for 20 years so none of that can be very important.

Very few refrigeration engineers know their stuff. It's like working in a tyre service center and not knowing what camber or caster is just because he only happens to repair punctures.
DTLarca made a very good point there.

Sensible Heat Ratio is preset at design given specific design parameters.

But when working conditions change, SHR changes.
Failing to recognise that, makes a epic failure of your job.
SHR is not a constant figure along the operational envelope.

There are many peeps who sit at their drwng brds believing that the world is perfectly round

In need of some examples of refrigeration engineers or installers failures?