Plumbing System Design

[knottybuoyz]

Just getting started with the plumbing diagram. Never having done this before I have no idea if I'm on the right track or not. It should be a lot simpler than the electrical but again.....

I'd like to use all Pex tubing & fittings, anybody with comments on this type of material? I know there are different mfgr & systems so any suggestions are greatfully appreciated.

Do you need "siphon breaks" on tank vent lines? I'm thinkin' yes but not sure.

The relative size of the lines drawn aren't representative of the actual size of the tubing/hoses I'll juse but I have drawn the larger dia hoses larger. I'm not sure exactly where I'll route all these tubes so that's not depicted accurately either.

I appreciate any feedback or suggestions.

[DeepFrz]

The 2004 Ocean Voyager contains an article by Dave Gerr on fresh water systems. He comments that his preferred fresh water tubing is Pex which can be purchased at Home Depot, etc.

He recommends stainless water tanks, filter between the tank and pump and a CV valve on output from the Accumulator (if you are going to have shore water connection).

He also has several plumbing schematics and they include vented loops on through hulls and goosenecks on vent lines.

Just a suggestion. In order to simplify the diagrams, keep the water system seperate from the fuel system schematics.

Cheers.

[Pblais]

Not sure I would have two waste and two potable water fills. With waste the short one is the keeper. I would have two fuel fills. I would add fuel / air vents to prevent fuel spills.

I would keep the waste lines as short as possible. When they clog or get old and start to smell every foot you eliminated is a blessing.

There are a lot of good choices now in water pumps. Personally I don't like Par Pumps. Some now are total on demand and don't require an accumulator tank. Look for flow rates more than 3 and maybe around 4.0. Reduce the number of fittings as practical. All those connections take time and hose clamps that can fail you. Make low spots with places to drain the system for EASY winterization would be number one.

For fuel make the tank with large enough inspection ports so you can really inspect them and have access so you can remove the tank without taking the hull apart. Ideally you should be able to install the tank as the last thing you do, then you know it will come out when the time comes.

As you build the boat and lay down the lines think about getting at anything after the boat is completed. It is possible to secure things without having to make it impossible to replace all the lines if you had to. Some day you'll have to get at something. There is always the temptation to tie wrap everything to everything else. Don't do it.

You still have propane lines left? I would consider how it all comes together with all the electrical and plumbing. Going under, over, and around and through takes a lot of planning to keep it neat, secured, and accessible.

Tip: Be sure you get the ALL STAINLESS hose clamps and when you put them on face the bolt so you can get to it easily later on. The chepaies don't use all stainless bolts.

[delmarrey]

I noticed that you have just one source of HW. Form your last drawing I assume it runs off the 110v shore power . Have you considered installing a secondary water heater that runs from a heat exchanger from your motor(s) heat exchanger(s).

One could plumb in a secondary line to the 110v water heater and keep it warm while motoring. It would take a small heat resistant pump to keep the water circulating.

While your out putt'n around you can still have hot water without using the inverter. As well, you could be heating the interior of the boat with radiators, unless it's propane all the way................................_/)

[Talbot]

I have water heater in one hull and an outlet in the other hull. Originally this was in 15m plastic pipe, and took a lot of water before getting warm. A lot of heat was wasted on such a long pipe.

When I changed the gas water heater to a rinnai so I could have a shower, I removed this 15mm pipe and replaced with 10mm copper. There was a slight reduction in throughput, but this was compensated by hotter water, and more than halving the waste of cold water before getting hot, especially as the smaller pipe enabled a different run which cut out about 2metres of pipe!

[GordMay]

Goto ABYC Standard “H-23" ~ INSTALLATION OF POTABLE WATER SYSTEMS FOR USE ON BOATS:

http://www.web-stir.abycinc.org/File...DARDS/h-23.pdf

And other applicable standards:

http://www.web-stir.abycinc.org/inde...on=PDFMainMenu

[GordMay]

Ensure that the holding tank vent line has a constant rise from the top of the tank to the vent fitting. Otherwise low spots may fill with sewage and act as a trap, effectively plugging the vent - hence anti-siphon Vacuum Breaks are not used on tank vent lines.
Vent lines should be as short as possible.

[GordMay]

PEX is an acronym for cross-linked polyethylene. The "PE" refers to the raw material used to make PEX (Polyethylene), and the "X" refers to the cross-linking of the polyethylene across its molecular chains. The molecular chains are linked into a three-dimensional network that makes PEX remarkably durable within a wide range of temperatures, pressures and chemicals.

There are currently three methods for producing PEX tubing, the Engle or Peroxide method, the E-beam or radiation method and the Silane method. All three processes produce tubing cross-linked to varying degrees that result in a product acceptable for potable water distribution applications. All PEX that has been tested and certified for potable applications carries the mark(s) of nationally recognized third-party certification agencies such as NSF, IAPMO, ICBO-ES, Warnock Hersey or UL.

The peroxide (Engel) method performs "hot" cross-linking, above the crystal melting temperature. It provides more consistent and uniform cross-linking with better control over the process. The process takes longer and tends to be more expensive than the other two, as the polymer has to be kept under high temperature and pressure for long time during the extrusion process, but it produces the best material. The product is classified as PEX-A, PE-Xa, or PEXa.

The silane method, also called "moisture cure" method, performs the cross-linking in a secondary post-extrusion process, producing crosslinks between a cross-linking agent (eg. vinylsilane) and catalyst added into the polymer matrix during extrusion, in one of the several processes, eg. Sioplas, Spherisil or Monosil. The process is accelerated with heat and moisture. Unlike the two other methods, the bonds are not between the carbon atoms, but are realized as oxygen-silicon-oxygen bridges, principally similar to the sulfur bridges introduced during rubber vulcanization. These links are somewhat weaker than the carbon-carbon bond, slightly impairing the material's long-term chemical stability. It is classified as PEX-B, PE-Xb, or PEXb.

The electron irradiation method is the "cold" cross-linking, below the crystal melting temperature. It provides less uniform, lower-degree cross-linking than the Engel method, especially at tube diameters over 1", and when the process is not controlled properly, the outer layer of the tubes may become brittle. However it is the cleanest, most environmentally friendly method of the three, as it does not involve other chemicals and uses only high-energy electrons to split the carbon-hydrogen bonds and facilitate crosslinking. The irradiation takes place after the HDPE tube is produced, and may be performed in a separated facility. The resulting polymer is classified as PEX-C, PE-Xc.

I recommend PEX-A (Engel method) products, such as Wirsbo “AquaPex”.

There are several methods of connecting PEX, all of which involve mechanical fittings. There are two approved standard specifications for PEX connections: ASTM F 1807 and ASTM F 1960. Both reference mechanical insert fittings. The crimp fittings specified in ASTM F1807 are the most widely used. Other fitting systems, including insert and outside diameter compression fittings, are also available. PEX cannot be joined by solvent cement or heat fusion methods.

PEX tubing can be used up to 200̊ Fahrenheit for heating applications. For plumbing, PEX is limited to 180̊ F. Temperature limitations are always noted on the print line of the PEX tubing. Recommended 140 max for safety and conservation.

PEX tubing is not intended for outdoor applications and must be stored in a covered environment not exposed to direct sunlight. Maximum UV exposure is no more than 30 to 60 days.

[knottybuoyz]

Thanks for all the input fellas. I forgot my thumbdrive today with the drawings so I'll work on something else. To summarize:

1. separate drawings for fuel, FW & waste systems.
2. single deck fills for fuel, FW & waste.
3. remove siphon loops from vent lines.
4. go to the library and pull the ABYC standards.
5. include specs for various pump types to indicate flow, pressure.
6. indicate inspection ports on drawings.
7. draw in engine = h/w heater lines.

I suppose I'm going to owe you all a boat ride when I get this thing built huh?

[DeepFrz]

You betcha...<GR>

This is probably a good time to design in fill pipes that are above deck level, so they will have to be against the bulwarks or against or set into the cabin wall. Deck fills have a nasty habit of leaking which can lead to contamination of F/W and Fuel tanks.

Geez, a boat designed by committee! <GR>

[markpj23]

Some of the AquaPex compression fittings I've used in home remodeling have seemed a bit on the weak side. Be careful not to over-torque and crack the plastic compression nuts. Seemed to me to be a great way to introduce a hairline crack that will eventually cause the fitting to fail - always at high pressure of course!

I sure hope that the chemists got it right this time... can't imagine another Qwest polybutylene pipe catastrophe happening .... I've got a lot of Pex to replace if they got it wrong

[coot]

Various thoughts:

Don't put all the deck fills together - it invites error. The least disgusting error is to fill your holding tank with fresh water, and it gets worse from there.

Your deck is probably sloped a little bit. Make sure the waste outlet is downhill of the water fill. Make sure water doesn't pool on any of the fills.

Most boats seem to have the fuel tank vent placed on the outside of the hull, so if you overfill the fuel a little bit, it sprays in the water. I always thought it would be a good idea if it spilled onto the deck, where you could wipe it up easily. The only problem is you need to find a place where water on the deck won't get into it. (i.e. it can't be just 2 cm above the deck...)

If the sink in the head has a retracting shower-head type faucet, you can use it for cleaning. e.g. You can pull it out and spray the wall, for example. If you do that, you would want either a shower sump for the head, or a way for water on the floor to run into the bilge. (Actually, when you are repairing the toilet, water will get out all over the place. You would probably like a drain for that anyway...)

[Boracay]

When the mechanic fitted the fuel vent to my boat I requested that it be arranged so that if a wave happened as it was sucking in air the water would not go straight to the tank. A position at the top of the cabin side with a loop to prevent water from going into the fuel was what I ended up with.
A water trap in the vent would have been nice.
In practical terms it is very difficult to have fills above the deck as the pipes are large and not easily routed..
As most boats end up as asymetrical (all of one function of one side of the boat ) it may be very difficult to have clearly distinct fills.
Clear colouring and labelling are more easily arranged.

[knottybuoyz]

Thanks for all the input guys. I breezed through the ABYC standards last night and combined that with your real-life input to come up with the latest revisions. I also went over the constructions photos of another TW28 that was built in Australia for hints. See attached photo.

Altogether I think it's coming together. I've doubled the tanks, FW, Waste & Fuel. All are cross connected. Potable water and diesel deck fills relocated to side deck. See attached photo.

Cleaning things up a bit meant I could keep everything on one drawing. I still have to spec out and create a proper Bill of Materials.

Again, thanks for all the feedback. Keep 'em comin'! Onto steering (hydraulic) next.

[DeepFrz]

I think the layout for F/W and Diesel fills is still very bad, IMHO. Of course it is the way they are installed in most boats, however I still think that they should be raised above decks so that they are much less prone to cross contamination. The normal deck fill depends on an "O" ring to prevent contamination from rain or sea water, or in the case of a fuel spill on deck, of contamination of the fresh water by diesel. Moving your waste water pumpout away from the fuel and f/w is a great start though. <GR>

I saw an example on the Steel Boat Society forum. The fills were stainless pipe with a pipe cap and they were up close to the bulwarks and raised above the level of the side deck. Of course you don't want them exposed so you would trip over them, so putting them close to a stanchion might help in that regard.