DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Plumbing Forum > Size of pipe (3/4" or 1/2")?




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Old 12-28-2013, 11:56 AM  
frankflynn
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Default Size of pipe (3/4" or 1/2")?

Hi,

I have a 1930's home and have over the years been replacing the original galvanized pipes with copper. The original galvanized was 3/4" everywhere.

For each bathroom I used 1/2" pipe because I wanted hot water sooner and with today's low flow faucets and shower heads 1/2" provides plenty of water pressure. This has worked well.

But now it's time to do the Kitchen, straight line from the Hot Water Heater which also has a branch to the dish washer and laundry. So the math is straight forward (I'm using the OD which is not technically correct but it's close).

5.3035714285714235 cubic inches per foot in 3/4" pipe
2.357142857142855 cubic inches per foot in 1/2" pipe

Or over the 40' almost 1 gallon (0.91836734693877) for 3/4"
and over 40' less than 1/2 gallon (0.40816326530612) for 1/2"

Seems like 1/2" is the way to go - but is this enough? My washer is a HE low water user, also the dish washer. Filling a bucket from the kitchen sink might take longer (it's not clear to be that the current hot water line is not filled with rust like the others were).

Any thoughts?
Frank



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Old 12-28-2013, 01:33 PM  
CallMeVilla
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Your conclusion is right ... The maximum number of fixtures for a 1/2" supply line up to 60 feet is seven ... Your usage is nowhere close to that.

BTW, if you want more performance in those "low flow" shower heads, you can remove or drill out the flow limiters ... I enjoy giving the finger to the water nazis.



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Old 12-28-2013, 02:17 PM  
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Quote:
Originally Posted by CallMeVilla View Post
BTW, if you want more performance in those "low flow" shower heads, you can remove or drill out the flow limiters ... I enjoy giving the finger to the water nazis.
I feel better now. I thought I was the only one to do this!
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Old 12-29-2013, 11:35 AM  
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Post #2 & #3,
" the depletion of a shared resource by individuals, acting independently and rationally according to each one's self-interest, act contrary to the group's long-term best interests by depleting the common resource."

I won't tell but No Such Agency (AKA Never Say Anything) might. . .

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Old 12-29-2013, 12:27 PM  
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Thanks, I go under the house and the 1/2" goes in today. (we need an emoticon on it's back with water dripping into it's face, no?)

As for the low flow fixtures - I've found that the quality of the low flow fixtures is hugely important. Some are just a weak imitation of a high flow (unrestricted flow?, high flow?, old style flow?) fixture - drilling these out returns them to their original specs. Others, were designed and built from the beginning with the idea of the full water experience for the user and to use less water to achieve it. Typically these have no restrictor.

You can't grab the first or the cheapest shower head you find and get the excellent shower experience that we're all looking for. But there are shower heads that will give you that and use much less water.

Many places have shower head ratings - Consumer Reports is my favorite but it does require a subscription. Amazon is another with several 1.5 GMP heads getting 4.5 stars (these ratings are from end users who we presume have used them not government officials or guys in a lab coat looking from the outside)

I too have mixed feelings about these "water nazis" but the alternative is a free market where you can use as much water as you want but the price will go up until the demand decreases to a level that can be supplied. On my utility bill water is one of the cheaper items and I suspect it would need to get a lot more expensive before the price alone would curb demand.

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Old 12-29-2013, 03:42 PM  
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"The cost of stars"
For choosing hotels I plot the number of stars given vs. the price and plot them. Visually you can see choices that are way off the trendline and then you can ask why. You can also get some idea of the scatter.

The same technique should work for these shower heads.

I do this for almost anything to get the practice in dealing with various datasets that I will come across in everyday life and to some extent I may be able to cancel out the countermeasures used by the sellers.

BTW, one advantage of forums is that I get to try to solve more and varied problems that I would ever encounter in one lifetime.



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