PEX Manifold a good idea???


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Old 12-07-06, 02:26 PM
Z
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PEX Manifold a good idea???

Hello,

I'm buiding a small siingle room house/cabin. It will have a shower, toilet, bath sink and kitchen sink. I'm going to have a propane on demand water heater in it as well.

The cabin's exterior walls will be strawbale. My current thinking (not even enough to be a plan yet) is to use two pex manifolds and pex tubing to distribute the hot and cold water. I was thinking I would put them in the attic space as there will be plenty of room up there, and then where I need hot/cold water, I will run the pex tubing through a PVC pipe inside the strawbale wall. The PVC pipe is just so that if the pex tubing was to break, it would not soak the strawbales, but would flow into the house wherever the pex pipe fiting was for that fixture.

First, does this seem like a reasonable solution? Any downsides you can think of?

Second, I choose pex because I've never done copper, and I don't really want to do copper and then have it leak on my bales. But I have absolutely no knowledge of how to do pex either, so.... am I crazy? Is it hard to learn? Seems like there are a couple different kind of connectors, which one would you recommend for my small installation (by a newbie)?

Third, are there any limitations to having the pex pipe coming directly out of the water heater? I.e. do I have to run copper for the first x feet or something like that?

Forth and finally, what size pex tubes to each fixture, 1/2" I assume?

Thanks in Advance.

-- bz
 
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Old 12-07-06, 03:39 PM
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OK, I'm going to bite on this one. I love intriguing questions. First off, we will need to know where you live for climate potential problems. Putting piping in attics in colder climates is a disaster waiting to happen. If there will actually be an "attic", what will be holding it up. All my hay bales barely hold my weight when I climb on them, so supporting a structure above them seems unwieldy.
Also it will help to know what codes you will be up against.
You can use pex to deliver hot and cold water, just make sure it is installed properly, and you can sleeve it through the walls with pvc if you like.
 
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Old 12-07-06, 03:55 PM
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Might try this www on PEX

http://www.plumbwithease.com/Installing-Pex-Pipe.html


ED
 
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Old 12-07-06, 04:59 PM
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I live in Silver City, NM. We have a fairly mild climate. A few days above 100 in the summer time, most highs in the high 80s or low 90s. In the winter we have many nights in the 20s and a few in the high teens. Winter highs range from 40s up to 70, rare that the winter high is lower then that.

My strawbale house (as many designs as there are builders) will have a pole building structure. The trusses will sit on a 2x that is attached to poles every 6 ft which are integrated into the strawbale walls, all of that is stuccoed on the outside and plastered on the inside.

I will have R30 in the ceiling, so the attic won't be getting much of the heat from my house into the attic, maybe I'll have to run the pex in the interior walls and inbetween the bales instead. That way it wouldn't be exposed to any of the heat/cool issues.

Thanks...

-- bz
 

Last edited by stickshift; 12-08-06 at 09:48 AM. Reason: Removed quoting of entire post
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Old 12-08-06, 05:15 AM
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I think Chandler was picturing a "Three Little Pigs" straw house.
 
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Old 12-08-06, 09:14 AM
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PEX is great..

My last house was plumbed with PEX and, when I remodeled my basement, adding a full bath and wet bar, it was the easiest plumbing I've ever had to do (big remodeler type here). Buy the proper crimping tool (actually an expander tool) from a online distributor ($160ish) to do it right. You can sell the tool on E-bay when you're done for about the same price, if not more (I actually made $$ doing so). The manifold will have to be copper from the hot water heater to the manifold /copper from your cold water main to the manifold - and PEX from there to your fixtures. 1/2 is fine as you're doing "home runs" to each fixture. As each line is a "home run" the chances of leakage are minimal - no joints in the hay bales. The only chances for leaks are at the connectors at the manifold and into each fixture. PEX is just a tiny bit more expensive than copper - but a whole lot easier to install. It's more resistant to freezing than copper - and certainly easier to run. You have a better chance of having PVC crack/break than you will the PEX.
 
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Old 12-08-06, 12:28 PM
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Not to get off topic, but I think Chandler and I were in the same boat... "strawbale cabin?"

http://www.strawbale-building.co.uk/index.php?page=pictures

http://www.neoanderthal.com/strawbale.html

I guess it's basically a pole barn type construction with bales of straw used for walls/insulation. Quite interesting. I wonder what the lifespan of the walls are.

Sorry for the tangent - I just found it interesting.
 
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Old 12-08-06, 02:32 PM
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Originally Posted by Zorfdt
Not to get off topic, but I think Chandler and I were in the same boat... "strawbale cabin?"

http://www.strawbale-building.co.uk/index.php?page=pictures

http://www.neoanderthal.com/strawbale.html

I guess it's basically a pole barn type construction with bales of straw used for walls/insulation. Quite interesting. I wonder what the lifespan of the walls are.

Sorry for the tangent - I just found it interesting.
My design is similar to what you describe, there are almost as many strawbale designs as there are builders. There are strawbale buildings that have been around since the 1800s, mostly in Nebraska where the practice was somewhat common during the settling days and the winters are brutal (so I hear, my Mother was born and raised there, not in a strawbale home though).

Back on the main topic , my next question is if you were to run the pex lines in pvc down the wall, what size pvc and both in one pvc pipe, or each in a seperate pvc pipe?

Also, will I have a problem with the 90 degree bends at the bottom of the pvc pipe (where it turns to come out of the wall next to the fixture)? I'm a bit concerned about the pex pipe being able to make the bend.

-- bz
 
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Old 12-08-06, 02:59 PM
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Also, will I have a problem with the 90 degree bends at the bottom of the pvc pipe (where it turns to come out of the wall next to the fixture)? I'm a bit concerned about the pex pipe being able to make the bend.


They have a small metal arm like that you slip over the pex and it makes the 90o like for you and holds it there
 
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Old 12-08-06, 06:10 PM
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That 90 degree bend is more like a sweep elbow bend.... slow and gradual to avoid kinking the plastic pipe.
 
 

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