Need help with plumbing design

[ilyafish]

Okay, so everything else i can seem to figure out...im stumped on plumbing.  I have no idea how any of it works....though chances are its alot simpler than what i am making it out to be.

Ok first off, the black tank will be pee pee only....no poo poo!  With that being said, i will be getting an rv toilet.  My first question is what do i need to set up the plumbing for the rv toilet to flush?  I literally no nothing about this.  I will probably be getting a Thetford.

Gray tank is pretty straight forward i pretty much got that.

Clean water tank.....I will be having a sink and a shower.  All i know is i have a clean water tank one one end, and a faucet and shower head on the other end.  I have no idea what goes in between them, water pump i assume?  Does the clean tank need anything special to keep the pressure?  What about fresh water stations at rest areas, do they have a special hookup or how do those work? How to set it up and all....i have no idea.  So i definately need help on this one.

Thank you guys!

[ilyafish]

oh i also forgot to mention that i am not concerned about a water heater or hot/warm water

[Jeremy]

I haven't built my system yet so I will leave someone else to give a blow-by-blow description; in principle though the system doesn't keep pressure 'in the tank' as such as suggested in your question - or at least it doesn't for the cold water, which is all you are asking about (some hot water systems do use a pressurized tank).

Instead the tank feeds the pump (via a filter), which then pressurises the pipes between the pump and the taps / shower. There are two ways of creating the pressure - either the system can be permanently pressurised through the use of an accumulator, or the system can be unpressurised at rest, but with pressure being built by means of a pump which switches on as soon as a tap is opened. There are also some half-way houses (pumps that maintain pressure with very small built-in accumulators, or even no accumulator at all.

My type of pump is a Jabsco - to begin to understand the various components you could do worse than look at the Jabsco website (http://www.jabsco.com/products/marine/water_pressure_systems/index.htm) - in particular some of the PDFs have illustrations of alternative plumbing circuits.

Jeremy

[Tenor]

Yup, Jeremy has it right.  The easy way is to plumb a line from the bottom of the freshwater tank, to the input side of the pump, from the output of the pump to your taps.  A cold line also needs to be sent from some tap nearby (with a T fitting, perhaps from the bathroom sink or shower) to the toilet.  A second line from the pump output (again, using a T fitting or manifold) goes to your hot water heater.  From your hot water heater, lines run to your taps. 

My pump is a standard Sure Flow that turns on with a switch.  Once the switch is on, it builds the pressure in the system, and shuts off once it reaches the right pressure.  When you open the tap, pressure drops, the pump pushes out more water.  I usually then turn off the pump. 

Some people put in a pressure tank (accumulator? I think we are talking about the same thing?) so that the pump runs less.  A pressure tank is a tank that has a rubber diaphram in it.  It works like a water balloon.  It takes water directly from the pump and fills the tank against the diaphram, making more space for water.  As water is needed at the tap, the diaphram pushes the water out of the tank until it is out of pressure, then the pump turns back on to continue supplying water or to repressurize the tank.

[ilyafish]

Yup....I remember reading about somebody using the rubber diaphram tank and it threw me for a loop.  Makes sense now!  What kind of water heaters do you guys use? 

Also, would i be using copper tubing for the taps and then pvc for the drains?  (ive never done any plumbing work ever)

Thanks guys!

[Tenor]

I used pvc for the drains.  Works just fine.  I bucked the trend on the supply side.  Most people use Pex tubing and their fittings.  It is an excellent product, allowing you to bend the tubing almost like hose, but a little stiffer.  They use a variety of different fittings now.  I just thought the stuff is too expensive.  My first bus had CPVC.  The only drawback to it is that it doesn't bend.  You need to use angle fittings to get around obstacles.  I used pvc reinforced vinyl tubing with barbed fittings and hose clamps.  It is good to 250 psi and just needs a knife and a screwdriver to install.  I read an old BCM article on the Motorcreek Moose Motorcabin built by MAK, and decided that it was a good way to go.  I do not reccomend copper.  It is much harder to install, and if you have a leak, your repair might be pretty hard to fix, or for that matter, the mistake you made during installation is much harder to fix!   I had only done a drain or two in my life, and I was had no problem doing the bus.

As for hot water heaters, I have a standard 6 gal. propane unit, probably by Atwood.  I also have a 6 gal. electric marine unit with a heat exchanger that i have not hooked up yet.

Good luck!
Glenn

[Jeremy]

Yes, accumulator is just a fancy name for the pressure tank with the rubber diaphragm.

Copper or plastic pipe can be used - I think the majority go with plastic (pex), and I know there have been various threads on this topic in the past.

Hot water heating is a much more complicated debate as there are lots of ways of doing it. My own route was to get a large calorifier (another fancy term, this time for a copper pressure vessel - like a domestic water cylinder on steroids). The calorifier has two heating coils inside it (by coil I mean a coil of pipe, not an electric element); one coil is connected to the engine to heat the water via the engine's cooling circuit. The other coil is heated by a Webasto (diesel) heater. By turning the appropriate valves either the engine or Webasto can supply the heating system in the bus instead of, or as well, as the hot water - or the Webasto can heat the engine itself to aid cold starting.

The calorifier option seems to be fairly unusual in bus conversions, but the main attraction to me was that your hot water is heated 'free of charge' by the engine as you drive to your destination - and because the calorifier is both quite large and well insulated your 'free' hot water should last several days with minimal reheating.

You can also get calorifers that have an electrical (immersion heater) element incidentally, but because of the size of the tank heating a calorifier electrically would really require a permanent shore-power connection, which I won't have when I'm camping. Instead I have got a small electric water heater as well, so if the big tank is cold I can heat up enough water for a shower or the washing up quite quickly.

That's my solution, others will do it totally differently.

Jeremy

PS. This is a Surecal calorifier identical to mine except this one does have an immersion heater (the big red thing in the middle). The small red adjustable valve at the bottom mixes a quantity of cold water with the hot water leaving the tank so the water that reaches the taps isn't too hot.

[Ednj]

-ilya,
Check out this site I just randomly picked a model but you will get the idea.

http://www.winnebagoind.com/diagram/2008/08_g33v_plumb.pdf

In the 70's the Winnebago brave had a metal water tank that had an air compressor that pressurized the tank to push the water to the faucets also self-winterizing.

[ilyafish]

Very interesting Ed!  Ok, so i have been doing some research all day and came across two pretty decent products, would like your guys's professional opinion on them.

For a water pump, what do you know about the 2088 Shurflo pump?

For heating water, I was going to tee off the Shurflo and go to a Stiebel Eltron DHC 3-1 water heater.  What do you guys know about this unit as well?

Is the Thetford Aqua Magic a good toilet as well?

Thank you all!

[TomC]

You need to rethink the no poopoo idea.  I have gotton sick, or food poisoning, and was very thankful for an on board toilet.  My tankages are 130gal fresh, 85gal gray, 45gal black.  It is enough so that my wife and I can dry camp for a week.  I also have 2-10gal elec water heaters straight from Home Depot.  One is plumbed into the next with the final water heater wired through the inverter for hot water going down the road.  Simple, just have to run the gen for about an hour before showering.  I have 2 water pumps in parallel, so that if one craps out, the other will also work.  I turn both on when showering, then when someone else uses a sink, doesn't affect water pressure.  I also have both a cold and hot manifold ball valves at the tank, so that if a water line or appliance blows, can just turn that one off and have the rest of the plumbing still working.  Have had good luck with all-been in for over 14 years with no failures and minimal servicing (translated, draining the water heaters once a year).  I don't think anyone with Diesel heat can say that.  Good Luck, TomC

[ilyafish]

Since we will never be drydocking for any more than one day, i was going to put in a 100 gallon fresh, 42 gallon gray and 20 gallon black. (I personally plan on emptying the black and gray tanks daily, so I am not concerned with having big tanks with the exception of the fresh tank which i may bump up a little bit depending on if i find a good price.

TomC i like your setup and may very well take alot from that.

[Rick Brown]

Here are a few photos
http://www.intermountainac.net/Bus/Plumbing01.JPG
I started with cu tube and replaced that with the high pressure clear PVC tubing, seen here, as sections of the cu tube froze and broke.  Short cu sections seem robust and the PVC withstands freezing well.  Shown is 1/2 inch tube, but I would use 3/8 if I did it again.
http://www.intermountainac.net/Bus/Plumbing02.JPG
shows the pump close by the 200 gal water tank under the bed.  No accumulator necessary.  Floor is raised so plumbing can run underneath.  Makes plumbing easy, but implies a roof raise.
http://www.intermountainac.net/Bus/Plumbing03.JPG
shows the composting toilet.
http://www.intermountainac.net/Bus/Plumbing04.JPG
shows the gray water tank and the only trap in the system.  When I drain the gray water I can close the hose bib valve at the top of the tank and thus suck a portion of the water out of the trap for freeze protection.  I know there is still water in the trap, but it seems to work as the trap has never frozen to death.
-RickBrown in Reno, NV

[John316]

Not sure if this helps, but we will be using Pex in ours. It seemed better than copper (it doesn't split when frozen) and it is a little cheaper, and bends.

Merry Christmas,

God bless,

John

[ilyafish]

Looks like Pex will be what i go with.  Now do you use pex for the sink and shower draining too? Or would i want to use pvc.  I would assume the shower would be pvc, the sink i could probably use pex

[John316]

Ilya,

Sorry I need to clarify. Pex is used for the fresh water. That is instead of copper. For your drains, you will want to use white PVC, or black Abs. You might want to get a Taunton book (Home depot should have it) on plumbing. The book will give you a rough idea on what you are looking at with plumbing. Research your system extensively. The last thing that you want is a leak on your bus.

HTH

Merry Christmas,

God bless,

John