Options for water tank vents?

[coopec43]

Originally Posted by Mexican Hat

Thanks for all the replies. Food for thought.

Coopec, I looked up that water maker you mentioned. Looks like a pretty good deal compared to the others out there.

Yes, I agree. The guy selling them acknowledges the Karcher pump won't have a long life but he points out you can buy them on Amazon for $89 so you can always carry a spare. (How long will an expensive pump last?)

Here they are for sale on sBay (read the write-up) and there is also a Youtube video clip as well.

https://www.ebay.com.au/itm/21-GPH-W...AP~:rk:13:pf:0

https://www.youtube.com/watch?v=6SYHVs-uZE0

[thunderhoof]

Sorry for the lengthy link but there are air control valves commonly available for water and hot water systems. The one below is brass and sells for 11.45 USD.

https://www.googleadservices.com/pag...9aACCFM&adurl=

[Mexican Hat]

Thanks Thunderhoof and Wakefield, those are the kind of valves I was hoping to find. I will order one or two and see what works best. The irrigation valve with the floating ball was how I imagined a solution so I appreciate the link.

[GordMay]

Why not use an automotive rollover vent valve?
https://www.onallcylinders.com/2015/...er-vent-valve/

[Mexican Hat]

Thunderhoof, I asked the supply house about the vent you referred me to. Apparently it only functions to release excess pressure and does not allow air to flow the other way. Good for filling, not so good for drawing down.

So it looks like the irrigation ball valve or perhaps, and thank you Gord, back to the original idea of an automotive roll-over valve.

[Mike Banks]

I simply ran a length of drinking water blue nylon hose from the tank top to the top of the galley, where it goes into one of those in-line filters used in garden irrigation systems. That stops any little critters making their way into the hose. The inside of the filter is looseley packed with stainless steel soap-less scrubbers. Air gets in or out, but dust and insects do not.

[thinwater]

I'm following this with interest. An excellent question.


But I do have a few concerns.

1. roll over valves have to be mounted above the filler. In many (not all) cases, it would be simpler at that point to vent outside the hull. If it is lower it will seep, which is annoying but not serious with fresh water.



2. The tank is slam full. Auto tanks have over pressure relief devises, but the water tank on your boat does not. At the very least, when the hot water heater comes on that volume will expand. Thus, you need to stop filling the tank before it is full.

3. Not all air releases allow air back into the system; many are one-way. The ag valve seems good, but the hydronic valve is probably one-way.

4. The relief needs to be MORE than the fastest you will ever draw water. Not a huge amount, but some of these valves are for pretty small flows and assume there is considerable pressure driving it.

None of these are show stoppers, just discussion points. This can work.

[Mexican Hat]

Thinwater, good points.

The hydronic valve is only one way so ruled that out.

My pumps are all manual, one galley foot pump and one head hand pump so I don't think flow volume is too critical.

The three tanks are only for drinking water, no water heating involved, but the vent fittings were installed an inch or so below the top of the tank so should allow for normal thermal expansion.

As for placing the vent, some more reading suggests that the valve has to be above the tank and with no 'p' trap like bends in it to ensure free air flow. So yeah, the positioning of the valve negates some of the advantage of not having to run a vent pipe up high. Will still provide the security of regulating overfilling though which was my main goal.

I have tried looking for bigger automotive roll-over valves. The biggest I can find is 1/2 inch but I'm uncertain if they work when liquid flows in from below or if they only work when upside down. Experimentation required. I'm going to order one of the ag valves and a large roll-over valve and see how they function.

Watch this space...

[Toccata]

Would this work?
Stainless steel pipe 200mm inside a stanchion, welded to the stanchion base.
Tail protrudes through to underneath the deck. Vent pipe connects to this.
Hole in the stanchion near the base (above the deck)
When the water tank is full, it will probably overflow from the filler point, but if the vent overflows it will seep out the hole in the stanchion.
Venting is generally a small amount of air, proportional to the size of galley pumps used, so the small hole should allow enough air to get into the vent line
If the stanchion ever goes under water, the small amount of salt water that may get into the vent won't matter?

[Mexican Hat]

Thanks for the revival of the thread and the help. I would have sworn I sent details of the solution I eventually came up, with but I don't see it in the thread so apparently OldTimers Disease rules...

I bought a couple of the irrigation system valves suggested by WRWakefield. (Many thanks, perhaps see you up in Alaska someday if you plan on staying up there)

https://amzn.to/2HcTgMB

And they work! Cheap, small, simple and effective. They allow air to flow freely past the sealing ball while filling the tanks and will seal when the tank is filled to the level of the valve. Water then backs up the fill hose and overflows from the deck fill. I mounted them just above the level of the tank and have tested them. They are not approved for drinking water but the most contact would be momentary at each filling, so any resulting chemical contamination is unlikely to be a major factor in my eventual and inevitable demise

They are ideal for what I wanted and seem to me to be a better solution than many of the others commercially available.

[Joli]

We vent water tanks to the galley sink. When the tanks are full they overflow there.