pur watermaker installation/engine intake

[rrgane]

i have been reading through the Katadyn manual looking for a likely place to install my watermaker, and it occurred to me that installing a 'T' off the water intake for the engine would be ideal right after the the strainer. the one concern i have is the manual warns not to install like this if there is negative pressure (i am going to assume that is big science talk for vacuum) at the 'T'.

i know that the engine cooling system is sucking water in, and creating 'negative pressure' but i do not know if it would be appreciable, and if it is, would installing a check valve solve it?

running the watermaker when the engine is not running wouldn't be a problem, but that seems pointless as that is when you would want to run it the most, grabbing electricity from the motor.

am i trying too hard to make it easy, and should i just bite the bullet and install an additional thru-hull?

thoughts?

[artbyjody]

I wouldn't install it off the sea intake for the engine - however, if you have a head on board - you probably have a water intake somewhere near. And that would make more sense to tap off a T anywhere down the line. Also another area would be the galley if it has a sea valve as well (some do as its used for the wash cycle - and fresh for the rinse)...

[Zanshin]

I might use another through-hull water source than the engine-intake one, but for a somewhat different reason - since watermakers are sensitive to oil I would choose one as far away as possible from the engine in order to lessen the likelihood of ruining the element.

[Freesail99]

I wil put another seacock in just for the watermaker. Nether place sounds like a good place to draw water, I would want to drink.

[sailingdog]

The best place to draw water for an RO watermaker would be a sink or A/C water intake. I wouldn't use the engine one for two reasons. First, oil contamination of the membrane will basically destroy it. Second, compromising the cooling water on the engine is generally a bad idea.

The head intake has the possibility of contaminating the filter with fecal matter... not too good an idea and a good way to destroy the RO membrane again.

If you don't want to install a separate through hull for it, setting up a raw water manifold might be a good option, if you've got another raw water through hull that you could put the manifold on.

One of my friends has an RO watermaker and the intake hose is rigged to the anchor washdown pump raw water intake, which is forward of both the head and engine, and reduces the chances of contamination from boat-related sources of possible pollution, at least while underway and to some degree while at anchor.

[negrini]

many boats does have a siphon killer, isolating any possible returning water, so it would be a double measure against the possibility. What really deny you using engine intake, is the strong negative pressure created by your engine raw water pump. Regardless the engine, this is always a big negative pressure on your "T". In case you make it, your entire running hoses, clamps, attachments, and all your gear at the watermaker, should have strong dimensions to stand such pressure. Your installation would have to be such a type of engine cooling system, rather a simple transparent and easy for inspection system. Even installing a check-valve, just imagine the amount of power to break it in, your poor pour would have to do. Sounds to me like those guys diving at 10 mts, thinking they could suck down air from a simple hose. Give up, and find another hole .....

[beej67]

Is there a reason he couldn't T it into the intake hose for his head instead? Maybe with a Y valve?