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Author Topic: Plumbing pipe sizes?  (Read 3256 times)
grantgoold
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« on: February 05, 2011, 09:47:45 PM »

Folks I am looking for some information on the size of your plumbing pipes. I am particularly interested in the kitchen, shower, bathroom sink, and toilet. I already have the sizes for waste/gray returns.

I have 3/8 pex tubing and 1/2 inch cooper pipe already on hand.

Sure would like to have good pressure when connected to public supply. Wife likes showers that dont require shut off during the experience.

Any help would be greatly appreciated.

Thanks

Grant
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Grant Goold
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« Reply #1 on: February 05, 2011, 10:17:56 PM »

bring the water in in1/2 then reduce to 3/8 going to shower and faucets . run 1/2 to water heater and back to 3/8
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JohnEd
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« Reply #2 on: February 06, 2011, 12:48:25 AM »

Grant,

I would make all runs in 1/2 pex, as in a house that has 90PSI.  Use your 3/8 inch stuff for the hot water return that goes back to the fresh tank from each HW valve.  Use this, with a button valve, to circulate the hot water back to the tank and get the hot water right up to the valve so you don't waste water letting it run to get hot before showering or anything else.  You can also use this to "heat" the fresh tank in winter using the HW heater and with design and insulation that could be your wet bay freeze proofing.

HTH,

John
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« Reply #3 on: February 06, 2011, 05:32:11 AM »

I used 1/2" PEX for everything.  Didn't bother with the HW return trick.

Brian
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« Reply #4 on: February 06, 2011, 05:42:12 AM »

Keep this mind 1/2 Pex and 3/8 copper are almost the same ID you add the crimp fitting to 3/8 Pex you are down to about a 1/4 inch our S&S job has 5/8 inch

good luck
« Last Edit: February 06, 2011, 06:39:25 AM by luvrbus » Logged

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« Reply #5 on: February 06, 2011, 06:30:27 AM »

I used 1/2" pex with 1/2" copper manifolds.  I wish I would have made my shore input 3/4" so I could fill my tanks quicker, but it's really not a big issue,
and I don't think I've ever seen a shore connection inlet in 3/4" anyway.

If you're using barbs for the pex, 1/2" barbs restrict down to about 3/8". If using the push in type connectors, there's little or no restriction.


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« Reply #6 on: February 06, 2011, 06:49:38 AM »

After your faucet temp selector in shower on the way to shower head there is a 1/4 to5/16   orfice going to shower head or reducer at shower head that limits flow.All that said I used 1/2 inch all way thru even thought it is reduced in end use to a much smaller  outlet.  FWIW    Bob
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« Reply #7 on: February 06, 2011, 07:05:29 AM »

Unless I am way off base here and that does happen Pex 1/2 inch is 3/8 Id without the barb fittings 3/8 Pex is not going to work for you very good so go with copper you have it will be 1/2 ID and the fitting will be the same

good luck
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TomC
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« Reply #8 on: February 06, 2011, 08:16:23 AM »

Use the Pex manifold for each plumbing fixture-then you could just turn off that one if you have a problem and continue to use everything else.  Use 1/2" going to each fixture, then use 3/4 coming into the manifold. Keep the pressure down around 45psi, but use two pumps in parallel for increased volume.  Good Luck, TomC
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« Reply #9 on: February 06, 2011, 08:37:25 AM »

If a a water line supplies more than two appliances it should be 3/4 if you work off a manifold all the supplies can be 1/2 inch and you will get plenty of water.

HTH

Melbo
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« Reply #10 on: February 06, 2011, 09:22:57 AM »

All have said what would have said. I would not put the 3/8 in. I did ours in 1/2 and find my system to be as good as my house. It works so well that when boomdocking I have to watch the water supply. I have a manifold and have the shower and bathroom sink on one hot and cold line and the kitchen sink and toilet are on the same cold water line. The kitchen sink has its own hot water line. I figured that the chances of running all them at once was pretty slim.

John
« Last Edit: February 06, 2011, 09:30:13 AM by Jriddle » Logged

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« Reply #11 on: February 06, 2011, 10:50:06 AM »

Grant,

I am just completing the water plumbing on my coach. I purchased two 1" Pex manifolds (6 port) with built in ball valves. I used one manifold for the cold water supply line and one for the hot lines. All of the lines up to the manifolds are 3/4" Pex and all of the supply lines from the ball valves to the fixtures are 1/2" Pex.

One thing I wish was different is that the ShurFlo pump has only 1/2" inlet and outlet?

I have 168 gallons of water and an 80 each black and gray tank. I am all plumbed up into the coach but I am going to look at adding the circulation back to the water tank to eliminate wasted water when waiting for the hot to show up.

I have filled the system and checked for leaks and I have run the pump and everything seems fine.

I am not sure I would use the Pex system again. A lot of money for fittings and I don't feel that the fitting availability is all that good. For those who still have plumbing to do buy the fittings on-line as they are half the cost of Home Depot.

Good luck, let us know how it turns out.

Doug
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« Reply #12 on: February 06, 2011, 11:19:54 AM »

I used 1/2" PEX for everything.  Didn't bother with the HW return trick.

Brian

This is how I did mine. Plenty of water and lots of pressure, even with dishwasher and laundry going at the same time.
On the drain side of things, I used 1-1/2 drains for the kitchen sink and the bathroom lav. The shower I used 2" and the toilet I used 3" The toilet is almost directly above the tank and so is the shower.

Good Luck
Oh I almost forgot GO STEELERS Grin Grin

Gary
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Gary Seay (location Alaska)
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« Reply #13 on: February 06, 2011, 01:13:46 PM »

Every time you go from 1/2 to 3/8 you are effectively putting a restrictor in the pipe. Also copper is not probably a good idea, you may have leaks at the unions due to vibration. VERY IMPORTANT to protect ANY kind of pipe at all/any rubbing points. My preferred method is to put a plastic sleeve on the pipe and then fill with some expanding foam as needed.
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« Reply #14 on: February 06, 2011, 01:21:18 PM »

Pip is right, avoid using any kind of rigid pipe, vibration will kill it. My 4104 is all flex tubing but my 4107 has a lot of copper tubing, a really bad idea.

Rigid can't be avoided for sewer pipes but the use of flexible connectors solves that problem.
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« Reply #15 on: February 06, 2011, 01:36:52 PM »

Your higher end coaches manufactures like Newell and Marathon offer a up grade to copper the few I been around was never a problem.
Face it guys the cost is why people use Pex not that it better you don't see it used in your AC, fridges, the OEM heating systems or your radiator lol

good luck
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« Reply #16 on: February 06, 2011, 02:26:34 PM »

Grant;

Remember in CA. that you need to use flex connectors on all gas appliances. Ours was all 1/2' Copper when we bought it. Gas door must be labeled LPG and unlocked while traveling the state

We use 1/2" Pex and shark barb connectors with the squeeze Rings. No returns to tank but want to install that feature.Tank shutoff to run direct from water regulated incoming pedestal supply.

You can use Pex and ball valves to make your own manifold for a lot less if you by on line. Put on a couple of extra valves for later use if needed and just cap them off.

Dave
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« Reply #17 on: February 06, 2011, 03:59:44 PM »

Pip and Gus gave some excellent advice that should be followed.  Luvrbus, the one that contradicted both is also 100% correct.  There is no rub between them.  Copper, tube or pipe, are superb and long lasting.  NEVER EVER use compression fittings in a RV.  I recently repaired a rotted floor bigger than the footprint of my HW heater due to a seep from compressions that I had insulated and wrapped many years ago.  It only dripped a little back under my kit cabinets wayyyyy back in a hole and it was just as bad a place to be working on plumbing as it is replacing the floor.  ONLY use those spiffy solder fittings and I don't care what the big boys do if they use compressions.  Solder is more fun and I felt like an old world craftsman and that is surely a stretch.

Pex has the advantage of surviving a freeze, I am told.  It is easier and cheaper.  It does not go around corners as well as copper and you can't make an install look as neat and professional.  For my money.  Oh, yeah, and pex doesn't even compare to copper in terms of polishability.

Do it your way.  They both work if you follow the rules.

John
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« Reply #18 on: February 06, 2011, 05:51:43 PM »

One pump, 1/2 "pex for all, large diaphragm pressure tank, no pressure problems with two showers.
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« Reply #19 on: February 06, 2011, 07:41:55 PM »

Why would I spend more money for copper to end up with a completely ridgid system that needs to be supported properly to avoid vibration?

I've seen some new million dollar houses plumbed with PEX and I wouldn't hesitate to buy a house with PEX properly installed in it. 
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« Reply #20 on: February 06, 2011, 08:01:47 PM »

In plastic, polybutylene was once the new and best thing. Look what happened there (though, I plumbed a house 25 years ago with it and it still works great; just have to tighten the fittings if you hard freeze the piping).

I'm doing pex because it is so easy, and is freeze tolerant. Copper tubing with flare fittings would work well in a bus, though expensive.

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« Reply #21 on: February 06, 2011, 08:05:54 PM »

 Brian,I don't recall Grant buying a million dollar house read the post he said he had 3/8 pex or 1/2 inch copper and you need to do your home work on copper some of it will stand a lot of vibiration.
Fwiw here in AZ they install the Pex in the attic and they are having a few problems with the heat in the attic I have a few of the million dollar homes around me and I see what happens the stuff could be the poly pipe of years gone time will tell.


 
« Last Edit: February 06, 2011, 08:14:49 PM by luvrbus » Logged

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« Reply #22 on: February 06, 2011, 08:29:22 PM »

Not to argue copper are anything, but in my bus the main reason I went pex is, when I went and picked it up, it was froze and busted. I looked at everything and thought I could just fix the busted places. When I thought I had a good spot, the copper was swelled and wouldn't accept a fitting. I pressure tested main runs and there were leaks everyware. In my bus these runs were buried in between the tiled floor and the sheetmetal in the bays and was sprayfoamed in.

So I had to completely gut the inside of the bus where all the plumbing is. I didn't want to take the chance here in Alaska to have it freeze again. I figured with pex the only place I might have a problem is the fittings. Also the pex was real fast and inexpensive. I used red for hot and blue for cold, so no second guessing. You also don't have to worry about water hammer as bad.

But copper is good. These are just my reasoning's. Wink

Gary
 
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« Reply #23 on: February 06, 2011, 08:39:18 PM »

If I was doing a bus today I probably would use pex also but copper is not bad the trick to both is make it assessable for repair when needed I have had to rip out cabinets,floors and walls to repair pex and poly same with the copper 


good luck
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« Reply #24 on: February 06, 2011, 08:48:58 PM »

One rule of thumb I make sure no matter how slight I make the runs down hill so in winter it drains to lowest point and winter drain.
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« Reply #25 on: February 06, 2011, 09:06:22 PM »

One rule of thumb I make sure no matter how slight I make the runs down hill so in winter it drains to lowest point and winter drain.

This is also what I did. I also have low point drains like you would see in the new S&S models.

Gary
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« Reply #26 on: February 07, 2011, 04:58:07 AM »

I have plumbed a couple of conversions in CPVC and as far as I know, they have been running around for many years without a problem.  Probably the cheapest and simplest way in a new conversion, might be hard to retrofit an existing one.
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« Reply #27 on: February 07, 2011, 01:25:16 PM »

The problem with polybutylene was only in the fittings, not the pipe. I have a bunch of underground PB pipe that has never leaked in 29 years, including fittings, plus all my feed pipes to faucets and toilets are PB with never a leak.

I don't know how its freeze resistance compares to Pex but it is pretty good.
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« Reply #28 on: February 07, 2011, 05:20:22 PM »

Grant, I ran 3/8 od 1/4 id. Very happy with it. I ran the lines to the bath and teed off. No manifold, used 1/2 at the hot water then teed off with lines to K sink and bath. I do not flush when I shower or use the sink. The small line gets the hot water to you faster, Not wasting water.  Tom Y
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« Reply #29 on: February 09, 2011, 06:49:09 PM »

On all of my fresh water pipes I used cvpc, 3/4in. comming in to tank and water heater. All other lines are 1/2in. cvpc. Have been full time for 8 years with no leaks or broken pipes. All sink and shower drains are 1 1/2in pvc. Comode is directly above tank so non problem there. Standard dump valves and hose connections. The only copper pipe is the tubbing used for propane lines.
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