Fresh Water Head and Effect on Calcification?

[Bossman]

Discharge hose

If the hose from my head to the holding tank was loaded with calcification (just replaced), should I assume that the discharge hose from the holding tank to the macerator is full of it too? And what about inside the tank?
Thanks

 

[catsailor]

That is an intersting question, and what I have been asking.

If the hose from my head to the holding tank was loaded with calcification (just replaced), should I assume that the discharge hose from the holding tank to the macerator is full of it too? And what about inside the tank?
Thanks

Why is it that certain surfaces scale and not others, and why is the hose particularly prone to this? In my work, we commonly use either PVF pipe or, better, Teflon lined hose, to get around thorny scaling issues, but I suspect the price is a deterrent in boats (http://www.hosecraftusa.com/configurator.php?modelUID=222) I am confident this would help, but at $55/foot..... I have searched, but have not found any reference to changing hose type in boats to fight scale.

As Peggy pointed out, being anerobic may increase the scaling potencial, but I suspect that is just a part of an equation that will not be fully understood. We know that sanitation hoses are designed to be odor-impermiable, but most serious chemical hoses easily pass that requirement. I suspect that other hose types have not been tried extensivly for price reasons, so we simply do not know. Silly, when we look at the big picture. But most would rather spend money on nice paint than function. It sells boats.

Time for an expereiment?

 

[geoffschultz]

I'm going to re-ask this question since it didn't get answered before:

Geoff, your friend is right that fresh water does eliiminate SEA water buildup in hoses...although some fresh water has a high mineral content that can result in "scale"...but much more slowly. However, I hope your friend has not connected a sea water toilet to his fresh water plumbing, 'cuz that's a BIG no-no! It cannot be done without risk of e-coli contamination of the fresh water, damage to the toilet pump or both...and EVERY toilet mfr. specifically warns against it in their installation instructions. There are only two safe ways to supply fresh water to a sea water toilet: a separate dedicated flush water tank that shares no plumbing with the fresh water system, or the head intake line connected to a sink drain. (I'm not sure exactly what sailingdog means by "the sink acts as a separator"....it's considerably more simple than that: sink drains are not connected to the potable water supply.)

Peggy, how do so many boats have fresh water heads then? Yesterday I talked to several manufacturers of trawlers that have fresh water heads, and none of them have a separate fresh water tank for the heads.

Also, Raritan sells fresh water flush systems. For example, please see http://www.raritaneng.com/pdf_files/obsolete/L297_sea_fresh_install.pdf

It would seem to me that I could plumb a similar system into my head. I don't want a system that requires filling a sink and using that to flush the head. Just ask the admiral...that's not acceptable. We cruise for 6+ months out of the year, and this has to be a permanent solution, not something cobbled together using a sink or the shower head.

-- Geoff

 

[sailingdog]

Geoff—

You can get marine heads that are designed to plumb into your fresh water system, but the manually pumped heads are not among them. Some of the marine heads are designed to flush using pressurized water. However, this means that you will probably be using a good deal more fresh water and need to fill the fresh water tank more often.

With the manual heads and some of the electric heads, the pump for the waste and the water intake are the same pump, and the chance that it would allow fecal waste matter to flush back and contaminate your fresh water system is the reason for using the sink or a separate fresh water tank for the supply.

 

[catsailor]

What SD meant, I believe, is that the sink creats an air-gap.

Geoff—

You can get marine heads that are designed to plumb into your fresh water system, but the manually pumped heads are not among them. Some of the marine heads are designed to flush using pressurized water. However, this means that you will probably be using a good deal more fresh water and need to fill the fresh water tank more often.

With the manual heads and some of the electric heads, the pump for the waste and the water intake are the same pump, and the chance that it would allow fecal waste matter to flush back and contaminate your fresh water system is the reason for using the sink or a separate fresh water tank for the supply.

That is why there is an air gap in the old-school toilet tanks, and that is why cooling towers fill with float valves.

I suspect a conventional backflow preventer will not work, in part because you are probably pulling water up to the toilet. Their are other issues, but I would need to be long-winded to cover them. They are to protect against brief water pressure drops.

Though there may be a more elegant way, I'm sure that a 2-gallon tank fitted with a float (like your bathroom toilet at home) would serve and would be safe. This could plumb to any marine head. My guess is that when the pressure water pump is not on it is going to refill very slowly (or not at all if your water tanks is lower), but that should not be a big concern; turn the pump on now and then.

So yes, you now have a very small secondary water tank.

 

[Peggie Hall HeadMistress]

Geoff, you needed to read my post more carefully

It's toilets designed to use SEA WATER--which includes all manual toilets--that should never be connected to the fresh water system.

Almost every mfr now makes at least one toilet specifically designed to use onboard pressurized flush water... because they are designed to use water from the fresh water system, it's safe to connect 'em to it. However, except for this one http://www.sealandtechnology.com/productpages.asp?pid=37, they're all electric.

Sailingdog said, "With the manual heads and some of the electric heads, the pump for the waste and the water intake are the same pump..."

That is NOT the reason it's unsafe to connect sea water toilets to the fresh water system. It's because, unlike household toilets, flush water goes directly into the bowl of marine toilets, and sea water toilets are not equpped with the necessary siphon breaks and backflow preventers to prevent bacteria in the bowl from migrating into the fresh water plumbing. And also because sea water toilets are designed to PULL in flush water...pressurized water is PUSHED into the toilet, causing seals, gaskets etc to become mis-aligned.

He also said that toilets designed to use pressurized fresh water use more flush water than sea water toilets. Just the opposite is true...they use LESS flush water (and less power too) than most sea water electric toilets.

Geoff, there's nothing "cobbled together" about a manual toilet that shares a thru-hull with the sink drain...several boatbuilders including Tartan have plumbed their toilets that way for decades because it eliminates one hole in the boat. It doesn't require that you always put water down the sink to flush the toilet all the time...sea water only stinks and minerals only build up in lines when sea water sits and stagnates in the system. So use sea water to flush...then use the sink to flush all the sea water out of the system before the boat will sit. Or, if you insist on flushing with fresh water all the time, there's a very simple way to add a dedicated flush water tank: Buy an UNvented bladder, any size you want. Find a location for it that's convenient to both the head sink drain line and the toilet. Tee the bladder fill line into the sink drain using a y-valve...re-route the head intake line to the bladder. No other plumbing needed. To fill the bladder, turn the y-valve and run water down the sink.

Btw, if you'd also paid a bit more attention when you are on the Raritan site, you'd have realized that by the time you got to the "Sea Fresh System" at the lnk you referenced, you'd scrolled down to the "obsolete/discontinued" part of the list. Raritan discontinued it years ago. They continue to provide manuals for it and some other discontinued equipment.

 

[geoffschultz]

Btw, if you'd also paid a bit more attention when you are on the Raritan site, you'd have realized that by the time you got to the "Sea Fresh System" at the lnk you referenced, you'd scrolled down to the "obsolete/discontinued" part of the list. Raritan discontinued it years ago. They continue to provide manuals for it and some other discontinued equipment.

Thank you for your information. I will point out that while the specific kit that I referenced is no longer available, all of parts which make it up are available. Thus I suspect that it's simply been replaced by a newer version.

-- Geoff

 

[sailingdog]

Peggie—

He also said that toilets designed to use pressurized fresh water use more flush water than sea water toilets. Just the opposite is true...they use LESS flush water (and less power too) than most sea water electric toilets.

Actually, what I said is that he would use more FRESH water, not that pressurized water heads used more flush water.... Any head that uses salt water for the flush uses LESS FRESH WATER by definition, and if you're using a pressurized fresh water flushing head, you're going to be filling the FRESH WATER tank far more often than if you're using sea water to flush the head.

Also, last I checked, the water going into a head goes through the pump before entering the bowl. The pump is a single cylinder with a dual action pump mechanism. As such, it is the fact that the intake side of the pump may be contaminated with fecal matter that is the real source of the danger. Even if the bowl were thoroughly disinfected and cleaned, the single cylinder pump mechanism would still be a source of contamination—the bowl is secondary as risks go to the pump mechanism using the same cylinder for the intake and discharge functions.

 

[John]

Ryd Lyme vs. Muriatic Acid

The manufacturers of Ryd Lyme claim that it is biodegradable. If they are only half right, I think that's a reason to use it vs. muriatic acid. I used it when I cleaned by heat exchanger, and I can testify that it works well. I forget the price, which is probably more than muriatic acid, but I still have half a gallon and, overall, the cost is minor compared to lots of other boat-associated products.

 

[BobM]

Well...as a chemist I'd say that muriatic acid is biodegradeable too. You put in water, it dissociates into H+ and Cl-, changes the pH of whatever is around it and it becomes part of the ocean (water...H+, OH- and salt...Na+ and Cl-...which is a huge oversimplification of course).

Ryd Lyme lists ~10% hydrochloric acid it active ingredient, which is muriatic acid (33-44% hydrochoric acid per JT Baker's MSDS). So just dilute (always acid into a larger volume of water as it will heat up substantially) the muriatic acid appropriately.

By the way...always use COLD water when trying to remove scale. Scale is worse in hot water because less soluble metal salts form, so using hot water could make things worse.

 

[Peggie Hall HeadMistress]

Sailingdog....<sigh>...

As usual you don't quite have it right...

Also, last I checked, the water going into a head goes through the pump before entering the bowl. The pump is a single cylinder with a dual action pump mechanism. As such, it is the fact that the intake side of the pump may be contaminated with fecal matter that is the real source of the danger. Even if the bowl were thoroughly disinfected and cleaned, the single cylinder pump mechanism would still be a source of contamination—the bowl is secondary as risks go to the pump mechanism using the same cylinder for the intake and discharge functions.

Yes, manual toilet pumps ARE dual action pumps that simultaneously bring in flush water and discharge bowl contents...but they do NOT recirculate waste through the intake! Flush water comes the through the top of the pump, bowl contents go through the bottom of the pump, and there are valves in the pump to prevent the twain from meeting...you will NEVER find any waste in the top half of a piston/cylinder manual toilet pump, or in the intake pump on an electric toilet, only in the discharge side of the pump.

It's bacteria, not actual waste in the plumbing, that puts potable water systems at risk if sea water toilets are connected to 'em.

 

[sailingdog]

Peggie....<sigh>...

Once again you're misquoting me. If you're going to criticize what I say, you might want to read it first. I never said the pumps re-ciruculate the waste through the intake. It really isn't my fault you jumped to conclusions on your own. As much as I appreciate your wisdom and advice on plumbing matters, I really wish you'd stop jumping to conclusions that aren't warranted. If you could point out where I said the pump recirculates the waste through the intake, I'd appreciate it... I also find it somewhat disappointing that you never responded to the mistakes you previously made regarding my earlier post.

What I said was that the dual action pumps can cause contamination of the intake side since the pumps use the same piston and cylinder for both the waste and intake. The risk of contamination of the fresh water supply from the bowl is significantly lower than the risk of contamination of the fresh water supply from the pump cylinder—which is filled with fecal matter when the pump handle is high, and intake water when the pump handle is pushed down.

Are you telling me that the pump piston and cylinder isn't going to be a source of fecal matter contamination—that somehow, the piston magically kills all of the fecal matter bacteria on the surface of the cylinder??? The clearances on most head pumps is not tight enough to prevent bacteria and fecal matter from contaminating the cylinder walls and being transfered from the waste side of the pump to the intake side of the pump.

As usual you don't quite have it right...

Yes, manual toilet pumps ARE dual action pumps that simultaneously bring in flush water and discharge bowl contents...but they do NOT recirculate waste through the intake! Flush water comes the through the top of the pump, bowl contents go through the bottom of the pump, and there are valves in the pump to prevent the twain from meeting...you will NEVER find any waste in the top half of a piston/cylinder manual toilet pump, or in the intake pump on an electric toilet, only in the discharge side of the pump.

It's bacteria, not actual waste in the plumbing, that puts potable water systems at risk if sea water toilets are connected to 'em.

If anything, my description of the risks of contamination is more accurate than yours... the real risk isn't from the bowl, but from bacteria in the pump cylinder. Or are you telling me that there is never any bacteria in the intake side of the pump cylinder??? Or that the risk of bacteria jumping from the bowl to the fresh water lines is somehow greater than that of the bacteria going from the pump, which they'd have to pass through, and which is connected to the the intake side plumbing?

I don't mind being criticized where it is due, but you're way off base on your last two posts criticizing me.