PEX in the attic or under floor?

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R

remout

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I live in the tropics of South Louisiana, however we do freeze up on occasion. I've got a raised foundation home with easy access to the crawl space. Also have easy to access attic spaces. I'm adding plumbing for the first time to this 121 y/o Cottage.

From a freeze up POV. I could run it all, home run style with no fittings in the attic, through the attic and that would probably be enough to not worry about freezing up. The drawback to this might be my cold water would be hot 9 months out of the year.

Perhaps I should run the cold side under the floor and insulate it. This way the cold stays cooler. Then run the hot through the attic and take advantage of attic heat 9 months of the year.

Any advice?
 
You can run it ether place. I wouldn’t go two different ways though. I think below is the way to go. I did the homerun on almost all of my runs except the second floor bath and I ran that up interior walls. I did all my homeruns with half inch and when I went upstairs knowing I was going to branch out for toilet shower and sink I ran 3/4. I wish now I would have ran the half inch up now. It just takes longer for the shower to get hot and almost never are more than one of the thing running at a time. If you do homeruns and you get out of the shower that is full of hot water and use the sink you will be waiting for hot again. Unless the run is very long or you are feeding several things that will be used together I wouldn’t go larger than half inch and on a long run don’t do the home run.
If you want to take advantage of the heat in the attic maybe put a whole roll of ¾ or 1” pex up there and really warm it feed it with half inch. I don’t know if that would work or not but it’s an idea.
 
I ran all home runs in my attic using 1/2". Gets hot here in south Florida and I have mixed feelings on in the attic. It was easier and I was concerned about having any connections in the attic. Attic runs do give you hot water in the cold lines but I just look at it as free solar heated water for hand washing and small use needs till it runs cold.
I'm on a slab but given the option, I might consider a crawl space under if I was sure I wouldn't get any critters gnawing on the plastic lines.
Your idea of splitting them is interesting but the logistics of top feed for hot and bottom feed for cold when feeding a shower or sink might be more work than it's worth.
The other consideration is the lengths of the runs from your manifold to appliances. 20 feet of 1/2 pex doesn't hold much water and just flushing out the hot water from the cold, or the cold from the hot line, would be pretty minor.
 
PEX is flexible. Even if it froze I don't think you would need to be concerned. It stretches instead of splitting like other pipes.
 
They've been installing pex and cpvc in the attics down here for years. Hasn't been an issue at all. Not much of an option when the original copper in the slabs starts leaking.
I suppose they said the same thing about copper when they built my house.....we've been installing it in slabs for years...!
 
There is a huge difference in regions. We get negative 30 F temps and pipes that venture outside the core of the house don’t last long PEX or not. On the other hand southern plumbing has all kinds of different approaches. It’s like night and day.

When I was in SC I watched two guys “Dig a Ditch” for some landscaping water lines. I expected a ditch and these two guys took all day digging by hand a thing I wouldn’t call a ditch it was about 4” deep. I told someone I could have made that “ditch” with my boot. That’s all the deeper they go. Last winter we had pipes freeze that were down 4’.
 
bud16415 said:
There is a huge difference in regions. We get negative 30 F temps and pipes that venture outside the core of the house don’t last long PEX or not. On the other hand southern plumbing has all kinds of different approaches. It’s like night and day.

When I was in SC I watched two guys “Dig a Ditch” for some landscaping water lines. I expected a ditch and these two guys took all day digging by hand a thing I wouldn’t call a ditch it was about 4” deep. I told someone I could have made that “ditch” with my boot. That’s all the deeper they go. Last winter we had pipes freeze that were down 4’.
Click to expand...

Quit digging, just drain or blow out watering pipes.
 
nealtw said:
Quit digging, just drain or blow out watering pipes.
Click to expand...

We do but when you have 50 miles of them under a golf course its not easy. Or when the cows need water in February.
 
bud16415 said:
We do but when you have 50 miles of them under a golf course its not easy. Or when the cows need water in February.
Click to expand...

That is not what I was talking about, Our landscape systems are just below ground level. If you forget to drain them, it is still a fairly easy fix next year.
 
Last house we replumbed was PEX in the attic. An important note .... we added thick insulation to both the hot and cold. In Summer, attics here get 110 degrees or more. The cold water from the attic was HOT. In the winter, that house will experience near freezing, so the hot water lines needed good insulation.

Since the house was on a slab, we had no choice. Previous owners had plumbed copper along the lower perimeter of the outside of the house. NOT a good idea.
 
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