Ready to get going with the plumbing! Need some help!

grantgoold · August 16, 2011, 07:19:46 PM

Getting ready to install the plumbing system. Will carefully layout all the elements before we actually begin. Need some adivse on size of tubing. We are going to use a PEX system including crimps, manifolds and the like. I am planning on a shut off valve for each location. Right now I am looking at the 6 outlet manifolds (radiant heat type) This will allow for expansion in the future should I need it.

What is your experience with each diameter pipe? 3/8, 1/2, 5/8......

Will be using expansion tank and two pumps. Will only have the following:

Shower
Vanity
Galley sink
outdoor service center and shower

Anyone's real life experiences with flow and pressures would be great.

Thanks in advance.

Grant

Melbo · August 16, 2011, 07:22:29 PM

With a manifold all you will need is 1/2 inch supply to each location

I also have found that only one pump is necessary to keep the pressure up and I don't have an expansion tank and have not found it to be necessary

HTH

YMMV

Melbo

robertglines1 · August 16, 2011, 07:28:52 PM

I agree with Melbo. I did use red for hot and Insulated hot water runs. Bob PS some front load washers require a 5gpm water supply.

DMoedave · August 16, 2011, 08:12:34 PM

what they said, 1/2 is perfect for your app. we have an expansion tank in our bus.

desi arnaz · August 16, 2011, 09:46:38 PM

I. Use half in my home and it works great,eve on a six headed shower head.

Sean · August 16, 2011, 09:55:14 PM

We also used 1/2" and are very satisfied with the performance. I don't think you'd be happy with anything smaller than that going to the shower, but you could get away with 3/8 for the sinks and commode. That said, I recommend sticking with 1/2" throughout because you'll get better pricing on the tubing by buying it in bulk, and having to keep track of only one size fitting makes things a bit easier.

Bear in mind that the larger diameter (1/2") PEX can hold a lot of water. The ID of 1/2" PEX is 0.475" for a cross-section of 0.177 square inch. That means that a foot of it will hold 2.13 cubic inches of water. Doesn't sound like much until you multiply by the length of your runs; a 27' run holds a quart.

By the time your hot water line gets from the water heater, to the manifold, to the shower or sink, it could easily be 27' or more, and that's a quart of cold water you need to dump out of the line before the water runs hot. Just something to consider.

As much as I would have liked to use blue for cold and red for hot, we could not justify buying two separate rolls, at a higher cost-per-foot. We went with the clear stuff throughout. And we used 3/4 PVC pipe for everything upstream of the manifold.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com

belfert · August 17, 2011, 02:56:19 AM

I use a Manabloc manifold in my bus. It works very nicely. The one caveat is you need to purchase adapters for the ends of the manifold for the cold and hot sides. I ran a 1/2 line from the cold side to the water heater and then the 1/2 line coming from water heater supplies the hot side.

I ran 1/2" lines to everything. I bought two 100 foot coils of PEX and have plenty left. One is marked with red ink and the other with blue ink.

robertglines1 · August 17, 2011, 03:44:08 AM

color: ck price was same reguardless of color here. Bob

Marcus · August 17, 2011, 04:25:05 AM

I used the manobloc as well . Pex with clamps. Also used the expansion tank. Marc

Scott & Heather · August 17, 2011, 04:37:43 AM

Two different colors were the same price. Get red and blue or white. Wasn't really exorbitant to buy two 100 foot rolls. $45 per roll? Nothing compared to how much we've spent on other "stuff". Color coding keeps the feeds clearly understood. We used SharkBite or GatorBite push-in fittings and LOVE them! No leaks ever...We used 3/4" from the regulator (do install a regulator) with a 3/4" tee to the water heater. Then both hot from the water heater and cold from the regulator were 3/4" that was "teed" off into the shower, toilet, bathroom sink etc. So 3/4" trunk with 1/2" feeds to toilet, shower, etc. no manifold....but, I do recommend an expansion tank if you are using a tank water heater. two reasons:

1. It will reduce the pressure drop in the, let's say, shower when someone turns on the kitchen sink or flushes the commode (do you have a toilet?). That kind of stuff.

2. The expansion of the water in the hot lines and the tank as it is heated is pretty amazing. I am installing an expansion tank to absorb the expanding heating water since right now when my water heater has completed heating my 30 gallon tank of water, it really pressurizes the hot water system...alot. Turn on the hot tap and it comes out hard for a few seconds.

Just my newbie take on it

papatony · August 17, 2011, 04:50:06 AM

Type of line right 1/2" with manifold. just run the hot line to the left side of faucet use the KISS system.

Sean · August 17, 2011, 07:07:28 AM

Quote from: robertglines1 on August 17, 2011, 03:44:08 AM
color: ck price was same reguardless of color here. Bob

Just to be clear, when I said we got clear for less than what blue and red would cost it was not because of a difference in the price of same-sized rolls, but because we were able to buy a single larger roll, which was cheaper by the foot. If we had used two different colors, we would have had to buy smaller rolls which were more expensive by the foot.

-Sean
http://OurOdyssey.BlogSpot.com

belfert · August 17, 2011, 07:32:28 AM

I'm wondering why Grant has two pumps? I don't think pump failures are all that common. I'll admit I did buy a spare pump, but I really have no idea why. The pump never failed when I had my travel trailer. I originally had two pumps plumbed into my system that both were switched at the same time, but those pumps were cheap and one wasn't really enough. They didn't work that well and I ended up installing a single Sensor VSD pump instead.

I suppose if you are fulltiming and boondocking a lot you could wear out the pump and need a spare. Even then, there are lots of RV dealers all over that have replacement pumps. I would be more concerned about carrying spares for items that could break in the boonies and disable the coach from being able to move. You can't carry spares for everything. I have one 18 gallon Rubbermaid container of spare parts. I have belts, some hoses, some hose clamps, fuel filters, coolant, oil, and some ATF in that bin. I may have an oil filter too, buy why I don't know.

Cary and Don · August 17, 2011, 08:09:11 AM

We have two pumps mounted because of failures. The first night out on our last trip the pressure sensor in our expensive Shurflo pump let go. Thank goodness for the pan under the tanks, because all 100 gallons of water went out the drain by morning. This pump is under the bed. Now there are two pumps mounted side by side so it's just a matter of switching the hose connections to make the change.

It seems, from the Shurflo people, that these sensors can be damaged by city water pressure. We do have a pressure regulator on the city inlet. We have also installed a check valve after the pump so the city water will not pressure against the pump.

Don and Cary
1973 05 Eagle
GMC 4107
Neoplan AN340

TomC · August 17, 2011, 08:37:39 AM

I used the Shurflo Whisper Quiet-two in parellel that works great. Granite there only about 35psi, but that's all you really need. With two, if one is showering, the other can still do dishes without the shower changing temperature.

You should seriously consider using a bigger manifold-it isn't much more. In your list you forgot the toilet (should be separate), and if you want to add later a washer/dryer, dishwasher, ice maker, etc. Good to plan for future expansion.

So currently your hot would be the shower, vanity, kit sink, outside faucet, and outside shower.
Your cold would be shower, vanity, toilet, kit sink, outside faucet, and outside shower. Good Luck, TomC