Help with connections for PEX: underground and indoors

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Aaron J

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Jul 25, 2022
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Hi,

I am replacing a PVC line with a PEX-A line. This line is used for our irrigation system. 1" PVC line ran from the main water line in our basement, out of the house (it will run inside 1.25" conduit pipe where it would briefly be exposed to sunlight), and into the ground where it connects with a 1" irrigation line (either HDPE or poly-b?). I cut the PVC line out, and have a single piece of PEX-A that runs the entire length from start to finish (about 25 ft). Where I really need help is with the connections.

We live in Montana where the climate is very cold (6 months of snow). My knowledge of plumbing is limited. I appreciate your help on this.

QUESTION 1: Can you help me identify the green irrigation pipe? HDPE or poly-b? I tried to search the text on the green irrigation pipe in google. I thought it was HDPE. But I am not sure now.

I had originally planned to use SharkBite push-to-connect couplings. However, the end of this pipe is too large to fit into a 1" tan color SharkBite fitting, which is supposed to fit HDPE. Maybe it is misshapen from its last fitting (I didn't cut off the end)? It does not look larger at the end than the rest. The green irrigation pipe's inside diameter is 1". The outside diameter is about 1 3/8". This made me think maybe it could be polybutylene. Do they make green poly-b? SharkBite does not make a 1 " push to connect coupling for polybutylene, so if it is poly-b, that option is out.

I am planning the following. Please help me know if this looks good.

CONNECTION 1 - 1" PEX-A TO UNDERGROUND IRRIGATION PIPE

If the irrigation pipe is poly-b, I will use one of the following on the irrigation pipe side:

If the irrigation pipe is HDPE, I will use

On the PEX side I will either of the following (crimp or expansion)

I was then going to wrap the threads with 3 wraps of Teflon tape and tighten (and pipe dope?). This connection will be buried.

QUESTION 2: Will this create a secure permanent connection? Is there a better way to do this? Are brass connections ok underground? Especially in freezing conditions?
QUESTION 3: Do I need to wrap the finished connections with silicon tape? I know SharkBite has you wrap their brass couplings in silicon tape when buried. Does that apply to all brass connections underground?
QUESTION 4: If this is poly-b and I use clamps, are the pinch better than the screw clamps? Or does it matter?



CONNECTION 2 - PEX-A TO METAL OR PVC / MAIN WATER LINE

There is a copper main line that was connected to the PVC. Our sprinkler blow-out guy added the drain last year (which I think was a good idea), and did some other work on this PVC line. Unfortunately, some of his work resulted in a basement flood and the need to replace the whole PVC line. Because of that, I don't really trust any of the work he did. I like that there is a drain to empty the line. But it is aimed against the insulation and very hard to use. I would like to replace it with another drain.

QUESTION 4: Can I easily remove this PVC pipe entirely here? Can I just unscrew the piece of brass it is attached to? Or would it be better to leave the PVC there and work with it?

Here is what I am planning

Unscrew the brass piece connected to PVC to from the backflow preventer (is there any problem with that), and remove the PVC section entirely.

These are the parts I am looking at:
With one of these to the PEX (depending on crimp or expansion)

And one of these on the copper side

I would wrap each of these fittings with 3 wraps Teflon tape and tighten as well as possible (and pipe dope?).


QUESTION 5: Would you recommend keeping the existing drain? (I would rather not).
QUESTION 6: Does this seem like a good idea for long term connections? Is there a better way?
QUESTION 7: The PEX is type A, so I have the option of expansion or crimp. I don't really want to want to buy both an expansion tool (it would be manual) and a crimp tool. Does it really matter which I use?



Thanks so much for your help on this!
 

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