Peggy: In your experience, does it matter how far above the toilet bowl the vented loop (from fresh water intake) can be??? My head quit pumping fresh water in after I properly secured the vented loop. I had to install the vented loop to prevent back-siphoning from the holding tank! You fix one thing, & break another... Thanks in advance for the advice!
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Wait a minute...
There's no way that a vented loop in the head intake line can cause backfill from the holding tank. There's no connection between the two. To be effective, all vented loops have to be at least a foot above the waterline at any angle of heel. The one in the head intake has to go between the pump and the bowl...if it goes in the head intake line between the thru-hull and the pump, the pump can't prime. However-- If your toilet is designed to draw flush water from the onboard fresh water tank, you don't need a vented loop in the head intake at all...in fact, you'll screw up the system by putting one in, 'cuz everything that's needed is designed into the toilet. If you decided (although I don't know why you would on a fresh water lake) to modify the toilet yourself to draw off the onboard fresh water system, it was a very bad idea...'cuz unless a toilet is designed to use pressurized water, there's a very real danger of polluting your fresh water system. Backflow into the toilet from the holding tank is an entirely separate issue. When the level in the tank gets high enough, heeling can send the contents back down the tank intake hose...and the cure for that IS a vented loop in the head discharge line. It can be right after the toilet, or right next the tank...and has to high enough to prevent the tank contents from getting over it at any angle of heel. However, if you'd replace the joker valve in your toilet at least once a year, it would keep any backflow from the tank from getting past it into your toilet bowl. That's what joker valves are designed to do.
There's no way that a vented loop in the head intake line can cause backfill from the holding tank. There's no connection between the two. To be effective, all vented loops have to be at least a foot above the waterline at any angle of heel. The one in the head intake has to go between the pump and the bowl...if it goes in the head intake line between the thru-hull and the pump, the pump can't prime. However-- If your toilet is designed to draw flush water from the onboard fresh water tank, you don't need a vented loop in the head intake at all...in fact, you'll screw up the system by putting one in, 'cuz everything that's needed is designed into the toilet. If you decided (although I don't know why you would on a fresh water lake) to modify the toilet yourself to draw off the onboard fresh water system, it was a very bad idea...'cuz unless a toilet is designed to use pressurized water, there's a very real danger of polluting your fresh water system. Backflow into the toilet from the holding tank is an entirely separate issue. When the level in the tank gets high enough, heeling can send the contents back down the tank intake hose...and the cure for that IS a vented loop in the head discharge line. It can be right after the toilet, or right next the tank...and has to high enough to prevent the tank contents from getting over it at any angle of heel. However, if you'd replace the joker valve in your toilet at least once a year, it would keep any backflow from the tank from getting past it into your toilet bowl. That's what joker valves are designed to do.
What is a vented loop?
Peggy I found another thread here and now have some more questions about the vented loop between the pump and the head. Is a vented loop simply a loop in the intake line which extends above the waterline or does it have to have the vent in it like the vent in the line from the head to the holding tank? What I see on our boat in the line from the head to the holding tank is a fitting with a valve of some sort in it which is attached to the flexible lines from the head and to the tank. It looks like a tough job on our boat to squeeze anything into the limited space between where the intake line leaves the pump and goes to the head (the head is a Groco HF).
Peggy I found another thread here and now have some more questions about the vented loop between the pump and the head. Is a vented loop simply a loop in the intake line which extends above the waterline or does it have to have the vent in it like the vent in the line from the head to the holding tank? What I see on our boat in the line from the head to the holding tank is a fitting with a valve of some sort in it which is attached to the flexible lines from the head and to the tank. It looks like a tough job on our boat to squeeze anything into the limited space between where the intake line leaves the pump and goes to the head (the head is a Groco HF).
A picture is better than 1,000 words, Tom
Get out your West Marine Catalog...or your BOAT/US catalog..or just about any catalog...
Find the section on plumbing, and there you should find pictures of vented loops--both enormous bronze ones, and more reasonably size PVC versions. And while you're browsing around in there, check out y-valves and other stuff too..it's much easier to spec out a system or changes to a system when you know what the parts look like. Online, prowl as many equipment mfrs as you can...many of 'em include exploded drawings of pumps, toilets, etc that show you what things like flapper valves, joker valves, diaphragms etc look like.
Get out your West Marine Catalog...or your BOAT/US catalog..or just about any catalog...
Find the section on plumbing, and there you should find pictures of vented loops--both enormous bronze ones, and more reasonably size PVC versions. And while you're browsing around in there, check out y-valves and other stuff too..it's much easier to spec out a system or changes to a system when you know what the parts look like. Online, prowl as many equipment mfrs as you can...many of 'em include exploded drawings of pumps, toilets, etc that show you what things like flapper valves, joker valves, diaphragms etc look like.I digress...
Peggy: Pardon my nomenclature! The "fresh water" in my question referred to incoming LAKE WATER from throughhull. I suppose my question should have been: Can one actuall have the vented LAKE WATER intake too high above the head? Or, do you think I just need to re-build my pump (Groco). You mentioned that the Joke valve should be replaced annually. Why not everything else in the pumps innards??? Thanks!
Peggy: Pardon my nomenclature! The "fresh water" in my question referred to incoming LAKE WATER from throughhull. I suppose my question should have been: Can one actuall have the vented LAKE WATER intake too high above the head? Or, do you think I just need to re-build my pump (Groco). You mentioned that the Joke valve should be replaced annually. Why not everything else in the pumps innards??? Thanks!
Lake water/sea water same-same
At least it is for the purposes of this discussion, so--except for my comments about using onboard fresh water, everything I said in my original reply still applies. It shouldn't be necessary to completely rebuild the head EVERY year...every other year in salt water, every 3 years in fresh, should be enough. I'd still replace the joker valve every year though. However, if your Groco toilet is a an HC or HE, both those models have been obsolete for quite some time, so I'd replace the whole thing before I'd spend money for a rebuild kit, 'cuz no other parts are available for 'em any more--and if your luck is like mine, the minute you spend the money for a rebuild kit, something will break that can't be replaced. Even if it's an HF--which is the current model, if it's 5 years old or older, I'd replace it before I'd rebuild it the next time it acts like it needs more than a joker valve (the same one fits all Groco heads btw)...a rebuild kit is about $50...you can buy the whole toilet for about $125...and I consider any toilet that can be replaced for around the cost of two rebuild kits to be a "disposable" model--not worth putting any money into.
At least it is for the purposes of this discussion, so--except for my comments about using onboard fresh water, everything I said in my original reply still applies. It shouldn't be necessary to completely rebuild the head EVERY year...every other year in salt water, every 3 years in fresh, should be enough. I'd still replace the joker valve every year though. However, if your Groco toilet is a an HC or HE, both those models have been obsolete for quite some time, so I'd replace the whole thing before I'd spend money for a rebuild kit, 'cuz no other parts are available for 'em any more--and if your luck is like mine, the minute you spend the money for a rebuild kit, something will break that can't be replaced. Even if it's an HF--which is the current model, if it's 5 years old or older, I'd replace it before I'd rebuild it the next time it acts like it needs more than a joker valve (the same one fits all Groco heads btw)...a rebuild kit is about $50...you can buy the whole toilet for about $125...and I consider any toilet that can be replaced for around the cost of two rebuild kits to be a "disposable" model--not worth putting any money into.
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