[the_nite_owl]

I am beginning to replace the 53 year old copper lines in my house with PEX as I am building a bathroom in the basement.
I want to put in a manifold to separate some of the lines and give a central location for shutoff controls.
Running individual lines to every fixture could be a bit expensive so I am trying to determine which lines are best to
Keep separate, which to combine and what the proper sizing should be for the lines before I go buy supplies.

I would like advice on the best configuration based on the fixtures and their locations.
My thought has been to keep the hot/cold lines independent for both bathrooms so they will have no pressure drops, and
Of course to supply the water heater with it's own line. Other items are not as demanding and I thought they might be
Good to combine along the same line to reduce the size of the manifold and tubing that has to be run.
My thoughts are to group items something like this:
Cold Water
1. upstairs toilet, sink, front outdoor faucet.
2. Basement toilet, sink, Workshop sink.
3. Kitchen sink, refrigerator, back outdoor faucet
4. Basement shower
5. upstairs shower
7. hot water heater, furnace (closed loop system)
8. Washing machine

Hot water
1. Upstairs bathroom sink, downstairs bathroom sink, shop sink.
2. Upstairs shower
3. Downstairs shower
4. Kitchen sink, dishwasher

I might consider combining hot/cold for the two showers or from the basment shower to the work shop sink since the
Plumbing would route easily to both and both are not likely to be in use at the same time. The run would be short for
Cold water but longer for hot. If there are extra connects on whatever manifolds I end up with it might be worth the extra line.

The current copper pipe is only 1/2" and I will be replacing with 3/4" where needed. I imagine 1/2" is good for most of
the fixture runs? Any benefit to making the shower runs 3/4"? I am not sure what size line the dishwasher uses but
Suspect the current tubing is more like 3/8".

I would appreciate any tips on grouping, routing and sizing. Once I have a plan in place I will begin putting together a
Parts list and measuring for total length of tubing I will need in each size and what connectors, valves, adaptors will be needed.
The first phase will be to plumb the upstairs bathroom to get the pipes relocated so the framing can go in for the downstairs
Bathroom and the rest of the job will be one section at a time as a new water heater is installed and possibly the furnace
Is replaced, both with wall mount direct vent gas systems.

The upstairs bath will be directly above the basement bath. The washing machine is on one wall of the basement bath and the workshop sink will be on the other wall of the basement bath adjacent the shower wall.
The water line coming into the house is right next to the basement bath and laundry area so things line up well for short shared lines where appropriate.

[the_nite_owl]

Here is a diagram of the layout of the basement and living areas to show fixture locations. It's crude but gives the idea.

[shader]

I replumbed my house (copper, PEX not allowed by local code) though I did use some PEX to run water to the attached garage-so my info is more general and FYI. First, mains are generally 3/4" with branches at 1/2", with no more than three fixtures connected to that branch. However, PEX manifolds have more than three branches & it is recommended that each branch supply only one fixture so as to prevent pressure fluctuation. That should help somewhat on the sizing. Second, the routing is a hard one; a lot depends on what type of access you have. Also, PEX has specifics for mounting/anchoring, bend radius, and allowing for thermal expansion. I bought my tubing at Menards, and they had a good brochure that covered fastening, manifolds, layout, etc. Hopefully, some with more PEX experience will post.

[the_nite_owl]

I figure the cold water line going to the water heater will need to be 3/4" and most others will only need 1/2". But I wonder if I am going to run a line that will eventually split to the bathroom sinks, toilet and outdoor faucet if that line should go out 3/4" and use a mini manifold to output into 1/2" connections where they need to break out so there is one larger supply line until the individuals are needed.
I also wonder if there is any benefit to providing 3/4" pipe to the showers but I guess if they will eventually drop to 1/2" it makes little difference if they are dedicated lines there anyway.

I have read about allowing for the thermal expansion but have yet to find anything on the fastenings or any best practices tips other than using a go-no go tester on crimp connections. There really is very little online info other than to say what a great product it is, nothing about HOW to use it in a large project.

[shader]

I agree, searching the web for PEX install revealed very little info, at least in my search. My suggestion would be to see if any of the home improvement stores in your area have brouchers like I mentioned. The one from Sioux Chief products is fairly comprehesive. For example, you MUST allow for thermal expansion/contraction in long runs; tubing must be anchored every 32" on horizontal runs & every 4' on verticals, etc. Not sure if any plumbing books cover this in detail. My two recent plumbing manuals from Stanley and Black and Decker barely address PEX installs. Sorry, can't be of more help.

[Joser]

You may already be aware of this but I think it says right on PEX and fittings that it should not be used in walls?
I don't think I would want to trust all those compression fittings inside my house. I used it for water out to the shop.

[the_nite_owl]

I have not read anything about PEX not being good for inside walls, everything I have seen talks about how to route it through the walls.

The older type polyethylene fittings had problems where they degraded and leaked causing a lot of people to have to tear up their walls to replace them but everything I have read on PEX sounds good.

I plan on using the crimp connectors rather than compression fittings unless for some reason I have to go to an odd size other than 1/2" or 3/4". And in those few instances the connector is likely to be in an accessible location for smaller tubing connections.

I just found the local Home Depot does not carry PEX but Lowe's does. Unfortunately Lowe's is about an hour drive from my house. *Sigh*

[shader]

Joser, I'm not sure where you got your info about pex not allowed in walls. All the major plumbing organizations have approved PEX pipe for potable hot- and cold-water plumbing systems and hot-water (hydronic) heating systems in all model plumbing and mechanical codes across the U.S. and Canada. Variations of these systems are placed under floors and in walls and ceilings. In a PEX "semi home run" intallation, a secondary branch maniflold(s) are used, and may be placed in the wall, especially on a multi-story house. As for the connectors, there should be a minimal number in the walls as each fixture should be supplied by a dedicated line. THe exception would be additional manifold connections and stub outs, where crimp ring connectors should be used.

[Joser]

OK good. I must be wrong. I was looking at some compression fittings, not PEX itself) I was going to us for PEX a few weeks ago and I thought I recalled they said not to use in walls.
My knowledge is very minimal so ignore what I said.

[Accepting]

Need to be aware of the Class action Lawsuit. Pex Uponor/Wirsbo/RTI

[massplumber2008]

Hi ACCEPTING...this is a post from way back in 2006... ;) Still, glad you posted to it as it gives me a chance to post the following info.:

__________________________________________________ ____________
__________________________________________________ ____________

As correctly pointed out PEX piping/fittings are allowed behind walls and cielings. As Joser suggested, it is compression fittings that are not allowed to be concealed.

Now... PEX SYSTEMS. Well, I happen to know where future readers can find a 128 page PEX BIBLE. Check it out at the following link:

FREE Residential PEX Water Supply Plumbing Systems Design Guide available on a PDF file (Thank you ToolBase!).






Anyone have questions just pop back and let us know.


MARK
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