PEX replacement

[not-a-plumber]

My son just purchased a single story ranch on an accessible crawlspace. The house was built in 1963 with copper supply lines. At some point the copper was abandoned in place and PEX B was installed. The brass fittings are white with corrosion and at least two fittings have failed in the past few months. The fittings don't appear to be the ones that were involved in a class action suit, and that time has run out anyway. But I'm pretty sure that the problem is dezincification. The house is on a well, I don't yet know the water PH. No chlorine, no water softener.
I have watched a bunch of youtube videos that seem to contradict each other regarding PEX A vs PEX B and expansion vs crimp fittings. I know that normally PEX A uses expansion fittings, but there is at least one expert who says that he uses expansion fittings on PEX B.
My guess is that I will just use PEX B with the solid copper crimp rings and probably upsize to compensate for the smaller internal diameter of the crimp fittings.

Specific questions:

Are the Apollo brand PEX tubing and fittings that are sold in big box stores acceptable, or should I go to a supply house for Zurn tubing and fittings? Or?

Brass, plastic or ??? type fittings?

Is there a good resource (video or written) with all the rules for running PEX such as when and where to use the 90 deg. radius fittings, required supports, minimum radius bends, distance from water heaters,...

Thanks for any help. I'd like to do this once and avoid any common mistakes if possible.

 

[breplum]

We plumbers who have been certified with the Uponor expansion type system typically attended a few hour "training" to get certified. I am a fan of PEX -a . The Uponor brass fittings are marked and comply with the dezincifation resistance , but your water chemistry may be beyond the performance criteria. At the trainings they hand out a manual Order a design assistance manual | Uponor

Pretty much I would think that if you watch you tube videos you will learn a lot.
Ideally, one would choose a single system to benefit from the advantage of mfr's warranty. I know Viega and Uponor offer those warranties IF you only use their proprietary products combined (tubing and fittings) and likely are certified.
My friend Peter Hemp has written "Plumbing a House" and he has updated it with a PEX section that is very good.
Around here, we use both plastic (mostly) and brass fittings w/o issues.
I would recommend the Uponor system and it sounds like plastic fittings where possible. But don't even try it with a manual tool, buy the Milwaukee 12v system or just hire a plumbing contractor for a day's work.

 

[Twowaxhack]

I’m not connected in anyway to this.....

But check it out. Stainless pex fittings. It’s 304.....

https://boshart.com/landing-page-pex-fittings/

 

[not-a-plumber]

Thanks for the replies.

I did get some water test results:
Iron ppm 0
Copper ppm 0.6
Total hardness ppm <50
Chlorine ppm 0
Alkalinity ppm 40
pH 7
nitrite ppm 0
nitrate ppm 0

Nothing seems out of whack to me. I don't know why the brass fittings are degrading.

 

[Twowaxhack]

Thanks for the replies.

I did get some water test results:
Iron ppm 0
Copper ppm 0.6
Total hardness ppm <50
Chlorine ppm 0
Alkalinity ppm 40
pH 7
nitrite ppm 0
nitrate ppm 0

Nothing seems out of whack to me. I don't know why the brass fittings are degrading.

Well water can change......
The brass may have been poor quality.