Vented Loops Squirting

[edeist]

Hello,
I am installing vented loops into my flush water intake and discharge lines. I bought these loops, which come with air valves attached: intake / discharge. I am finding that they squirt water as I attempt to flush the toilet, and I am not sure if it is because they are faulty (they're brand new!), or if there is some other problem with my system. The vented loop on the intake side is between the pump and the bowl, and the vented loop on the discharge side is between the bowl and the Y-valve that splits between the holding tank and the thru-hull. Here is a schematic of the system. One thing that I didn't quite get right in the drawing is that the holding tank is quite high - the inlet to the holding tank might be as high as or higher than the top of the vented loop. I am not sure if that is important.
Thanks in advance for any advice!
Emma

 

[Joe]

Your installation is correct. The problem is in the tiny flapper valve. First, make sure it is inserted into the air hole correctly, that would be with the pucker side facing down to let air in but not allow water to surge out on the pump stroke. Then your next move is to adjust the cap tight enough to prevent water forcing its way around the threads but loose enough to ensure good action. I've considered smearing a little lithium grease on the threads to help the seal... but I've never actually tried it so it could be a no-no. Perhaps someone else might comment on that.
Anyway, mine needs adjusting regularly... I'm glad it's convenient and in plain sight... so when it does leak I can tend to it right away... takes like a second to do that.

 

[Peggie Hall HeadMistress]

Hi Emma...welcome to sbo.com!

Air valves should prevent squirting, so yours may be defective. I'm not sure what Joe is talking about...it should only be necessary to thread the valve into the nipple on the top of the loop.

However, though it prob'ly isn't the reason they're squirting, you've also put the loops way too low. They need to be at least 6-8" above waterline AT MAX HEEL, not just when the boat's at rest...which on most sailboats including yours, puts 'em 2-3 FEET above the bowl (See attached photo). That would put the loop in the toilet discharge line above the top of the tank, giving you a downhill run from the loop directly to the tank inlet fitting--or to a y-valve that lets you choose between flushing into the tank or directly overboard...the lines coming off the y-valve should go straight to their destinations--tank and thru-hull...no deep dips in 'em.

Btw...my book (see link in my signature) explains how to plumb a system in considerable detail...the title (my publisher's idea) is a bit misleading...'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to install, operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is! I think you'll find it useful...And I'm always glad to answer any questions it doesn't.

--Peggie

.

 

[edeist]

Thanks Peggie and Joe. I'll check out your book!
If the air valve is defective, do you have any recommendations on where to buy a new one?
Regarding the height of the loops, what's a good way to estimate the water line at max heel? This should depend on where on the boat the vented loop is right? Am I correct in thinking that in the middle of the boat, the water line is always at the same height? I thought I'd put the vented loop very close to the middle (under the v-berth in my case) and be able to be above the water line at max heel without actually being very high up.
Let me know if this is faulty reasoning... Thanks!
Emma

 

[Peggie Hall HeadMistress]

The waterline changes as the boat heels...so it gets higher, the further you're heeled, whether on purpose or due to wind and water conditions. The best place to mount the vented loops is directly--or slightly to one side in either direction--above the toilet. This photo should give you a better idea of how high above the bowl it needs to be.

I hope someone else who knows how to graph the waterline and max heel of the typical 29' sailboat will jump in here with it...;cuz that'll make easy for you see why you can't put vented loops low in the boat.

I wouldn't be too quick to assume that your air valves are defective...let's see if moving the loops to their correct locations in the boat will solve the squirting problem.

--Peggie

 

[justsomeguy]

Am I correct in thinking that in the middle of the boat, the water line is always at the same height?

I believe this is reasonable to assume.

 

[dlochner]

Am I correct in thinking that in the middle of the boat, the water line is always at the same height? I thought I'd put the vented loop very close to the middle (under the v-berth in my case) and be able to be above the water line at max heel without actually being very high up.

Pretty much. A point closer to the center of the boat will move less than points further away. However, it may be easier to mount the vent in manner Peggie shows.

Mount the V-loop above the toe rail height or roughly at the level of the side deck and a couple of feet inboard from the hull. This is usually pretty easy to locate from inside the boat. This will always put the loop above the waterline unless the boat is routinely sailed with side decks completely awash with water lapping at the side of the cabin. This might happen with a midship location, but not in the forward cabin or aft cabin.

Mounting the loop high and close to the head puts gravity at work, as it will be downhill from the loop to the holding tank.

 

[heritage]

Peggie.. do you recommend a vented loop on the discharge if it goes only to a holding tank with no overboard discharge?

 

[Peggie Hall HeadMistress]

Mounting the loop high and close to the head puts gravity at work, as it will be downhill from the loop to the holding tank.

...which gets flushes to the tank with a lot less pumping so you don't fill up the tank with flush water.

And Dave...we need to talk...'cuz even after 30 years solving folks' marine potty problems, I'm not too old to learn and I've never heard of this before, so do not understand it: in the middle of the boat, the water line is always at the same height. If actually talking makes it easier to explain it to me than swapping a bunch of messages, send me a PM and I'll reply with my phone number.

Peggie.. do you recommend a vented loop on the discharge if it goes only to a holding tank with no overboard discharge?

A VENTED loop, no...but a loop, maybe. It depends on a couple of things...distance from the toilet to the tank, and whether it's an uphill run. When either or both conditions exist, installing a loop immediately after the toilet (aim the discharge fitting straight up) that's even just an inch or two higher than the inlet fitting on the tank can provide a lot of help from gravity 'cuz you only need to flush enough to push bowl contents over the loop...gravity will get it the rest of the way. Any toilet that working anywhere close to factory specs can lift bowl contents up to 4' even in the dry mode...so learning to use the dry mode to do more than just push the last bit of water out of the bowl, then following with a just a couple of pumps to rinse behind the flush, can increase the number of flushes your tank can hold by as much as 50%.

--Peggie

 

[dlochner]

And Dave...we need to talk...'cuz even after 30 years solving folks' marine potty problems, I'm not too old to learn and I've never heard of this before, so do not understand it: in the middle of the boat, the water line is always at the same height. If actually talking makes it easier to explain it to me than swapping a bunch of messages, send me a PM and I'll reply with my phone number.

Peggie, we can talk. Try this simple demonstration.

Draw your self a cross section of a sail boat hull and draw the water line. Put the drawing on something soft or at least something you don't mind sticking with a pushpin. Find the waterline. In the middle of the hull at the waterline stick the push pin. Now take a ruler, hold it parallel to the waterline at the push pin. Heel the boat. Notice it pivots around that point. If for some reason that point goes below the waterline, there are way bigger problems than a back siphoning head. I'll try to shoot a quick video tomorrow.

BTW, the folks on the Sabre group were missing your presence earlier today. I directed them here.

 

[Joe]

Thanks Peggie and Joe. I'll check out your book!
If the air valve is defective, do you have any recommendations on where to buy a new one?
. Thanks!
Emma

I googled "forespar vented loop cap" for you. Here's one source I've used before... there are many others. Btw way, my valve will spit when the boat is upright at the mooring... got nothing to do with heeling. I've taken the flapper out and cleaned it... the re inserted it but not too tight or it is difficult....apparently I don't know what I'm doing though, so perhaps it's time to order another if it annoyed me enough.. but it doesn't cause it's easy to adjust.