Check valves vs vented loops

njlarry · Sep 26, 2014

Stu, I hear you friend but hope springs eternal.
I understand that many newer boats use fresh water and also some heads are designed that way. Seems like there should be some way to modify the plumbing to also use the fresh water tanks for flushing. Maybe some combination of anti-siphon and check valves??
Meanwhile I use a modified version of Peggy's system. Raw water flush alternate with fresh water.

thinwater · Sep 26, 2014

The only reason I don't know the answer to this one is because I don't really care enough to test it. I happy with my system as is. But...

Why not this, as a miniature water closet? A nifty salt-to-fresh conversion kit? http://www.mcmaster.com/#float-valves/=tw8v7v

The reservoir looks to hold about 20 in3, or about 12' of 1.5 ' hose. Enough for a flush in most cases, and I'm sure there are larger sizes. The refill rate is 0.3 gpm, so refill would be complete in 20 seconds. Much like a home toilet. Make little mounting bracket, hook the pressure water to the inlet, and you're good to go. I'd throw in a spring check, just to be certain, and a pair of valves for selection and isolation.

----

Worth the trouble and weight? Not to me. Something for others to investigate.

thinwater · Sep 27, 2014

David Popken said:
Peggy, any response to the Practical Sailor artilce that I scanned and attached hereto?

I'm not Peggy, but...

I don't think the picture tells you as much as you think. Though it looks like the head is gravity drained into the tank, I think that is only an artifact of rendering and not what Dometic intended. What they did intend to illustrate is...
* There is no dirrect over board option. For better of worse, all waste must go into the tank. For most weakend wariors and all inland sailors, this is best. If there is no dirrect option and the tank fills from the top, there is no need for a vented loop since there can be no syphon.
* They are selling macerators and controls as a packaged system.
* They are selling vent filters. Peggy believes these are the spawn of the devil; many have been installed poorly and caused serious trouble. She believes in big vents, which work. However, properly installed, vent filters last 2-4 years and work well. The refills are pricy, but they are trivial to DIY fabricate, in which case refills are $5 (http://sail-delmarva.blogspot.com/2014/09/carbon-holding-tank-vent-filter-lasts.html). For most people, however, the larger vent (1 1/2") is a simpler answer. The stock 5/8" vent is the wrong answer in all cases.

In fact, Dometic sells their own expensive and super stiff sanitation hose that is suposed to resist permiation; some testing says it is good, but much suggests it still fails in 5-7 years. But if you google threads you will find there are much better answers. Trident, Shields, and Raritan all have better primium products.

Peggie Hall HeadMistress · Sep 28, 2014

David Popken said:
Peggy, any response to the Practical Sailor artilce that I scanned and attached hereto?

The drawing is so low res that when I enlarge it to even 50%, it's so fuzzy I can't really see much. So regretably I still don't have enough info to comment.

And btw...I do NOT consider filters to be "spawn of the devil'...I only wish I could have invented something that solves a problem it also creates!

Filters can be useful where a misguided builder or owner put tank in the bowels of a bilge, or in deep tanks (contents below about 20" turn anaerobic of necessity...or tanks too large to make aeration practical. They should only be a last resort when all attempts at passive ventilation and/or aeration have failed to eliminate odor.

Stu Jackson · Sep 28, 2014

njlarry said:
Stu, I hear you friend but hope springs eternal.
I understand that many newer boats use fresh water and also some heads are designed that way. Seems like there should be some way to modify the plumbing to also use the fresh water tanks for flushing. Maybe some combination of anti-siphon and check valves??
Meanwhile I use a modified version of Peggy's system. Raw water flush alternate with fresh water.

No, no and no.

Let's try this again, Larry:

Larry, you simply don't want to do that. The reason is that you could contaminate your fresh water supply.

And I'll add: with a MANUAL simple head.

Yes, there are sanitation (head) SYSTEMS, that DO use fresh water and you can buy them and install them.

With the links I provided in my last post, that should answer all questions for MANUAL HEADS.

You simply do NOT need to "alternate."

You need to USE the head, the seawater is just fine, and use freshwater for the last one of the day. The reason the seawater stinks is that it has been SITTING in the hoses.

The reason the holding tank vent stinks is because you haven't treated it with Odorlos, and increased the vent size.

Head Odors 101.2 The Difference between KO & Odorlos (scroll up to Reply #2) http://forums.catalina.sailboatowners.com/showthread.php?p=890493&highlight=odorlos

UNLESS, you buy and install a SYSTEM that is designed to use fresh water.

Why anyone (without a watermaker, that is

) would bother to use (the limited amount of freshwater that is usually found on a recreational vs. "bluewater" boat), is simply beyond me.

If smells are an issue, the answers are out there. Actually right here in this thread.

Stu Jackson · Sep 29, 2014

OK, Larry, you win.

http://www.defender.com/product.jsp?path=-1|51|2234284|2234293&id=2622882

I do not know anything about this product, I only am posting this because I "found" it on another boating forum.

Peggie Hall HeadMistress · Sep 29, 2014

Stu Jackson said:
OK, Larry, you win.

http://www.defender.com/product.jsp?path=-1|51|2234284|2234293&id=2622882

It's a brand new toilet, Stu...first ever manual toilet designed to use pressurized flush water....only went into production about a month ago. Read the thread I started in this forum on a 8-14.

If you spend a little time studying the Defender page, you'll see that the design is nothing like the usual piston-cylinder manual pump...with good reason. Sea water manual toilets are designed to PULL water through the pump...pressurized water is PUSHED through the pump, which can move the seals, o-rings etc out of alignment--just one of the reasons why they should never be connected to the fresh water system. Raritan's new "Fresh Head" uses a valve and a diaphragm pump, plus the vacuum breakers and backflow preventers needed to protect the potable water system.

All of which comes back to, ONLY toilets that are designed by the mfr to use pressurized flush water should ever be connected to the boat's fresh water plumbing.

njlarry · Sep 29, 2014

Thank you Stu, that is a good find but I haven't won anything as I still don't have a way to convert my Jabsco to fresh water unless I can find room for a separate dedicated water tank.
Peggy, is there no way to add the siphon breaks and valves that are inside the new heads to current ones upstream of their water intake?
(like I said before....hope springs eternal)

Peggie Hall HeadMistress · Sep 30, 2014

If your only goal is to eliiminate sea water odors and mineral buildup in the toilet plumbing (waste is so full of bacteria that fresh or salt water makes no difference in the holding tank, only in the head diischarge hose), that's easy to accomplish on most boats. All you need to do is reroute the head intake line to the head sink drain line...tee it into the sink drain line just above the seacock. (Your former head intake thru-hull will now be available for use with a washdown pump, or you can even remove it and glass over the hole.)

You'll continue flushing with sea water, same as you've always done...till you're ready to close up the boat at the end of the weekend and go home. Last thing, after you've closed all the thru-hulls (which you do if you're smart), fill the sink with clean fresh water...flush the toilet. Because the thru-hull is closed, the toilet will pull the water out of the sink, rinsing all the sea water out of the WHOLE system--intake line, pump, channel in the rim of the bowl AND the discharge line. If you find yourself in skanky coast waters, you can keep the thru-hull closed and used sinkfuls ofclean fresh water to flush all the time. This also makes winterizing a lot easier...instead of disconnecting the head intake line to stick it into a jug of antifreeze, just pour the antifreeze down the sink while you flush it through the system into the tank. Done in 5 minutes.

There--all the sea water problems eliminated without the need for a new toilet or a separate flush water tank or any new plumbing.

I'm gonna be at the Annapolis Sailboat show next week...helping out the Odorlos booth on Friday and Saturday. If you're planning to come to the show, stop by and we can chat about this.

njlarry · Sep 30, 2014

Thank you so much Peggie. If we go to the show, I'll bring your book to autograph.