Shower-only plumbing - shower body valve replacement

[Not a plumber]

Hi Everyone. Was hoping to get some advice on how to best replace plumbing in my upstairs standup shower only stall. It's 30 years old and almost no pressure so I took it apart to investigate and eventually got to the valve body output being clogged with white calcium type buildup. Rather than try to clean it out and risk reclog sooner than later, I'd like to just replace it. It doesn't look that bad in the pic below but it was almost completely filled up before I scraped and vacuumed it out partially.

My question lies in plumbing a new shower valve body. The attached picture represents the way the shower body valve instructions shows it should be plumbed on the left, and how my current shower body valve is plumbed on the right. The extra vertical pipe doesn't appear to be hammer arrestors, just capped off plumbing that extends 18" or so up past the valve body.

Should I re-create this plumbing scheme that is currently there? Is there any benefit or drawback? I was actually wondering if having that extra water above the valve kept it full and led to quick build up of calcium or whatever it is. Or maybe having that extra water helps to keep the valve seals fresh?

Any advice would be appreciated. Thanks for your time.

 

[TomFOhio]

I would pipe it like your drawing on the left hand side. If those pipes just go up and are capped they aren't doing anything anymore.
If your not getting any slamming of the pipes you don't need any arrestors.

 

[Not a plumber]

Thanks for the input Tom. I am curious why it was plumbed this way in the first place. I will take your advice and just elbow from the new valve into the lines below.

 

[Twowaxhack]

Thanks for the input Tom. I am curious why it was plumbed this way in the first place. I will take your advice and just elbow from the new valve into the lines below.

They’re called air chambers. It is meant to capture air and act as a water hammer arrestor.

It works until the air dissolves into the water, so that means it doesn’t work.........

Remove them and don’t look back.