2" pex in attic, upsize then downsize

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Pghsebring

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If the incoming waterline to the house is 3/4", and then it ran through 100ft of 2" pex in the attic, and then was converted back down to 3/4" before branches off to faucets, etc, would there be any noticable water pressure issues? Is there a plumbing code it violates to upsize then downsize again?
 

Reach4

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If the incoming waterline to the house is 3/4", and then it ran through 100ft of 2" pex in the attic, and then was converted back down to 3/4" before branches off to faucets, etc, would there be any noticable water pressure issues?
The 100 ft of 2 inch would not introduce water pressure issues. That would be a very unusual thing to do. You can pre-heat the water in the summer that way.
Is there a plumbing code it violates to upsize then downsize again?
Permitted.
 

Pghsebring

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I live in miami, what do you mean "in the summer"?

2" is the largest pex i could find online.

Got the idea from my friend who just spent 2 years in bahrain, she said the faucets have two temperatures, hot and hotter.
 

Jadnashua

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I lived in Kuwait for awhile, and during about 9-months of the year...the 'cold' water was too hot to use without tempering. We used the WH, which was turned off, as our cold water supply, and it was a major problem when the water in it was replaced with the hot from the roof until it had a chance to cool off again. We only used the WH for hot a couple of months a year. I think your solution is more bother and would suggest you just keep the line the same size and forget about trying to use it for heating. If I did my math right, 100' of 2" pex would hold about 16g verses about 2g in 3/4" pex. Personally, I'd prefer cool water at least out of the cold faucet, not hot.
 

Pghsebring

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I lived in Kuwait for awhile, and during about 9-months of the year...the 'cold' water was too hot to use without tempering. We used the WH, which was turned off, as our cold water supply, and it was a major problem when the water in it was replaced with the hot from the roof until it had a chance to cool off again. We only used the WH for hot a couple of months a year. I think your solution is more bother and would suggest you just keep the line the same size and forget about trying to use it for heating. If I did my math right, 100' of 2" pex would hold about 16g verses about 2g in 3/4" pex. Personally, I'd prefer cool water at least out of the cold faucet, not hot.

I was thinking of only doing the hot before the water heater.

15 gal over and over again....
 

Jadnashua

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As a solar preheater for the WH, it may work. ON those rare days when it gets quite cold, since you wouldn't want to insulate it so it COULD get hot, on those days, it could get quite cold...worst case, and I know they're rare, it could freeze. There's a reason why running pipes in the attic is usually done beneath the insulation, right near the ceiling...the temperature is moderated and protected from the uninsulated attic above.
 
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