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Author Topic: Pex plumbing lines? Size does matter!  (Read 4004 times)
grantgoold
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« on: August 22, 2008, 04:30:50 PM »

Trying to get some idea of the size of the water lines for my bus. I plan on using PEX.

What size have you used?

Thanks

Grant
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Grant Goold
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FloridaCliff
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« Reply #1 on: August 22, 2008, 06:24:30 PM »

3/4" trunk line

1/2" to fixture

In the short run of a bus, should be just fine, as a matter of FACT, it does work just fine.....

Cliff
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grantgoold
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« Reply #2 on: August 22, 2008, 06:28:57 PM »

Is 3/8 too small? I have folks that have an entire lot of PEX line and connections they want to give away but I do not want to put something into the system that is too small.

Thanks

Grant
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Grant Goold
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FloridaCliff
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« Reply #3 on: August 22, 2008, 06:34:09 PM »

Is 3/8 too small? I have folks that have an entire lot of PEX line and connections they want to give away but I do not want to put something into the system that is too small.

Thanks

Grant

Grant,

I would use the 3/8 as the feed to the fixture without worry, but I would still run a 3/4 trunk for the volume....

Cliff
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1975 GMC  P8M4905A-1160    North Central Florida

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« Reply #4 on: August 22, 2008, 06:34:53 PM »

Grant,
PEX is 1/2"OD ans 3/8" ID. I've been using 1/2" for the last 8 or 9 years with no problems except a FUBAR activating switch.

Shurflo has a download to figure out what you need to set your system up.

http://www.shurflo.com/pdf/rv/911_trouble_shooting/new/911-352-I.pdf
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FloridaCliff
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« Reply #5 on: August 22, 2008, 06:43:31 PM »

Grant,

On using the 3/4.....

Have you ever heard anyone complain about too much volume of water...... Roll Eyes

Next............. Wink

Cliff

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1975 GMC  P8M4905A-1160    North Central Florida

"There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded."
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« Reply #6 on: August 22, 2008, 07:07:14 PM »

Grant,

On using the 3/4.....

Have you ever heard anyone complain about too much volume of water...... Roll Eyes

Cliff


Yeah! When something breaks!

Jay
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kyle4501
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« Reply #7 on: August 22, 2008, 07:51:34 PM »

Since I'm the one dumping the holding tanks  Embarrassed . . . .
Since I don't have any hair to wash  Shocked . . . . .
Since water = weight & weight = more fuel  Cry . . . .
Since the less water you use, the longer a 6 gallon hot shower lasts  Grin . . . .


I'm gonna use 3/8 . . . . unless 1/2 is cheaper   Shocked

My airstream is plummed with 3/8. The shower has lower flow than the house, but still enough for a great shower - long hair takes longer (but I don't have to wash my back every time  Shocked )


Besides, if someone doesn't like the shower in the camper, they can use the campground facilities.  Wink
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luvrbus
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« Reply #8 on: August 22, 2008, 08:45:46 PM »

 Grant,what would be the propose of using a tubing size larger than the pumps inlet and outlet I have the 5.7 smart sensor pumps and they have 1/2in inlet and outlet and work on about 60# of pressure.Mycoach is all 1/2 in  good luck
« Last Edit: August 22, 2008, 08:49:37 PM by luvrbus » Logged
Tony LEE
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« Reply #9 on: August 23, 2008, 06:22:48 AM »

if you do mostly boondocking then the smaller the diameter the less water you waste waiting for the hot water to arrive. Ways around it of course but running small hot and cold pipes from a central manifold to the individual points results in much less pressure fluctuations - especially in the shower - when someone turns a tap on elsewhere
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makemineatwostroke
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« Reply #10 on: August 23, 2008, 06:50:26 AM »

I would follow your pump manufacturers guide lines these pumps are going to pump just so much water period the larger the pipe the less pressure you are going to have after the initial start.I have never owned a RV mostly Blue Birds with larger than 1/2 inch tubing with 2 pumps,besides 1 size tubing is easier to carry parts for than 3 sizes
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Damn Yankee
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« Reply #11 on: August 23, 2008, 06:52:19 AM »

I used 1/2 throughout my system and it works just fine. Also used sharkbite connectors (http://www.sharkbiteplumbing.com/?gclid=COyihLmKpJUCFQkmIgodS2hfbQ) for the t's & 90's. had my fresh water system together and working in less than 2 hours with no leaks!
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Nick Badame Refrig/ACC
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« Reply #12 on: August 23, 2008, 07:48:35 AM »

Hi Guy's,

Cliff has stated the proper way to do so.

Weather or not 1/2", 3/8", or 3/4 pex works for you for a manifold before branch runs, is your personal choice.

I plumbed my system the proper way for 2 reasons, water volumme and resale value!

If thats not important to you, then do it your way. It will still work!

Good Luck
Nick-

 
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luvrbus
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« Reply #13 on: August 23, 2008, 08:38:35 AM »

Grant, fwiw the flow rate on 1/2 in pipe is 5 gpm on 3/4 in it is 12 pm but the flow rate is as good as your 2.8 gpm or 5.7 gpm pump you are not going to get 12 gpm with a RV pump no matter what size pipe you use according to the Boyles and Charles law for water distribution. It looks to me that  the 5.7 smart sensor pump would be ideal for a 1/2 pipe with just a small amount left over
« Last Edit: August 23, 2008, 09:09:36 AM by luvrbus » Logged
belfert
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« Reply #14 on: August 23, 2008, 08:45:28 AM »

I have a manifold with 3/4" inlets and 1/2" PEX outlets.  The 3/4" inlets don't help much as my tank outlets are only 1/2".
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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