Holding tank arrangement. Please comment

[Weyalan]

Here is the proposed head/ holding tank arrangement for Insatiable.

I welcome your comments / advice / criticism




Key:
1. Inlet thru-hull fitting - bronze, 3/4"
2. Ball valve - stainless, 3/4"
3. Inlet hose - 3/4" (Is this appropriate?)
4. Toilet - Type to be determined, probably 12v (as opposed to manual) with macerating pump
5. Outlet hose - 1.5" (Is this appropriate?)
6. Y-valve
7. Vented anti-syphon loop
8. Holding tank - Polyurethane? 5/16" or "3/8" thick? ((Is this appropriate?))
9. Y-valve
10. Ball valve - stainless, 1.5"
11. Outlet thru-hull fitting - bronze 1.5"
12. Pump - Type to be determined, probably 12v maverator pump (as opposed to manual)
13. Y-valve
14. Holding tank vent line with filter
15. Deck fitting with vent valve? (suggestions?)
16. Deck fitting with pump-out coupling? (suggestions?)

[MidLandOne]

The anti siphon loop needs to isolate EVERYTHING from the sea so is last

[Weyalan]

Sorry, are you saying that the siphon loop needs to be between the inlet fitting sea-cock and the toilet itself? (Yes, I am a "newbie" at plumbing)

[Steve Pope]

you will also need an anti syphon on the inlet, bring the inlet up to a position that will always be above the water line when heeled on either tack before running it back to the toilet.
I suggest that you google lavac or Blakes and look at the layouts shown there and choose the one for your particular setup.

[Boracay]

If you can have the holding tank so that it is above the waterline then you can leave the inlet (provided it has the appropriate antisyphon valve in the hose) and outlet seacocks open and the ocean should stay where it belongs.

The "Y" valve right after the toilet could then be dispensed with if you like added safety and simplicity (and a few wiffs of sewerage) ahead of convenience, risk and a lack of odour.

[MidLandOne]

Originally Posted by Weyalan

Sorry, are you saying that the siphon loop needs to be between the inlet fitting sea-cock and the toilet itself? (Yes, I am a "newbie" at plumbing)

Both the holding tank and the toilet need to be protected from the sea by the anti siphon loop on their discharge side ie one side of the loop should go to the discharge seacock and the toilet and holding tank be on the other side of the loop.

As Steve says you should also have an anti siphon loop on the flushing water side of the toilet to protect the toilet from the sea. The toilet installation instructions should tell you how to do that

As Boracay says you can do without the holding tank being protected from the sea by the discharge side loop but only if ALL the tank is well above the waterline - an unusual circumstance in a sail boat unless the tank is very small. However, I consider it best to do as I laid out then everything is protected from the sea except for the hose to discharge seacock joint and the hull fitting itself.

There are several ways to arrange the 3 port valves to achieve the above and I would suggest that you look at some of the manufacturer's and other literature on the internet to see exactly how it can be done.

[Wotname]

Is the top of the toilet bowl above or below worst case heeled waterline?? This in part determines the need for anti syphon loops but fitting the loops is always better (syphon wise). There is a greater danger with smaller bore plumbing when it comes to syphoning.

BTW what shore based pump out facilities exist in Tassie or is the holding tank just for trips further afield?

[MidLandOne]

Until I saw Wotname's post I did not click that you are just across the Tasman. While this is a bit old and only shows one way (I think, I haven't read it all recently) similar to the arrangement you are trying to achieve (Figure 3) you may find it useful-
www.mfe.govt.nz/publications/water/sewage-systems-for-boats-nov99.pdf

But check pumpout connection size with local conditions (they are supposed to be universal though). In the Figure 3 type arrangement you can revamp that to put the deck pump out connection on the discharge side of the anti siphon loop if wanted.

Obviously the comliance content in the publication refers only to NZ.

John

[cal40john]

The vented loop that others have said should be installed should go between the pump and the bowl. If you put the vent before the pump it will be on the vacuum side and you will suck air in through the vent.

Whether vented loops are required depend on the relationships of the parts to each other and whether they are below or above the waterline.

I don't think that the pumpout will suck through an impeller macerator pump, so the pump can't be where you have put it. Why a second macerator if you're going to have one on the head?

Your setup is fairly complicated, you have to get 3 Y-valves set right to make it work. Good sanitation hose doesn't bend in a tight radius. Do you have a lot of space?

What is becoming mainstream around here anyway is for the head to pump into the holding tank. Then you would pump the holding tank overboard at an apropriate time, or go to a pumpout. Only one Y-valve required. (or even none, I just used a tee)

This link very similar to what I have, including the two vents and the pickup tube. The waste pump is a diaphragm (electric or manual) pump. One thing I like is that all openings in the tank are on top, a pickup tube is used for the outlet. So no leaks, and no trying to remove a dead macerator from the bottom of a full tank.

Good Old Boat: Marine Sanitation Devices by Mark Parker

Here's the Raritan diagrams for plumbing the PHII, there are others for their other heads on that site. Note that they say the loop just after the head to the tank is recommended to prevent backflow into the head, not required.

http://www.raritaneng.com/pdf_files/ph_II/L04v0505.pdf



I used mostly PCV plumbing. For the pro and con discussion:

http://www.cruisersforum.com/forums/...-use-6889.html



2. Why a stainless seacock, you're already using a bronze throughhull.

John

[Weyalan]

Looks like it is back to the drawing board. Thanks for all the good advice and links. I already decided bronze seacocks are the way to go. I'll post a revised layout soon. Cheers

[Weyalan]

I do have a couple of other questions though...

Around here we don't have to have holding tanks at all (I'm putting one in because I want to, not because I'm obliged to), so as a result, pump-out facilities are few and far between. So, the question is; will it ever be necessary to be able to physically pump the contents of the holding tank out through the pump-out deck outlet, or will all pump-put facilities have the pump capacity to suck iit all out without any assistance from on-board systems?

Also, would a 12v maverating pump be the way to go for pumping the tank to the through hull outlet (when offshore), or would some other sort of 12v pump be better (assuming it has already been macerated by the toilet pump)? Or would a manual pump be better?

Next. If I understand the posts above, a vented loop on the inlet side of the toilet needs to be between the pump and the bowl, because if on the suction side fo the pump, it will not function properly becauseit will suck air through the vent in the vented loop. That being the case, one must either (a) put the vented loop between the pump and the bowl, or have a solenoid operated vented loop that closes when the pump operates (as per Jabsco 12v toilets). Does anyone have any opinions on such solenoid operated doo-dahs? (my prejudice is KISS, but I'm often wrong)

Finally,is it worth having an extra inlet into the tank to for flushing it out, or is it viable to just flush it by pumping water through via the toilet?