Max height of vented loop from head output

[Canonshooternb]

I am looking to freshen up my head and storage tank on my boat. It currently has a holding tank and overboard discharge. In proper designs what is the max height rise that the vented loop should be installed above the base of the head ? I understand the purpose of the loop but find that sometimes I get backflow into the bowl.

Is there any diagrams with proper design measurements ?

 

[Peggie Hall HeadMistress]

You can find some guidelines in the installation instructions for your toilet.
You actually need TWO vented loops--one in the discharge line and one in the intake...but not in the line between the thru-hull in the pump...that one belongs between the pump and the bowl. You should find a drawing in the installation instructions that illustrates this. As for height above the toilet...loops need to be at least 6-8" above the boat's waterline AT ANY ANGLE of heel...which, on most sailboats, puts it 2-3 FEET above the bowl. There is no maximum height for the intake loop, but because 4' is about as high as any toilet pump can lift bowl contents, that's as high the one in the discharge line should go. Put it immediately after the toilet...aim the toilet discharge fitting straight up. (See photo)

As for backflow into the bowl...water runs downhill. So any waste or water that hasn't made it over the top of the loop will run back down to the bowl. A worn out joker valve will let it run INTO the bowl. A worn out joker valve will reduce the pump's efficiency too...so it's important to replace it at least annually. Learning to use the "dry" mode to push it over the loop will reduce the amount left to run back down considerably.

If you still have questions, I'll be glad to answer 'em.

 

[Canonshooternb]

Hi Peggy, First off thanks for responding and sharing that information.
I will attach a photo of my system for a reference and ask for some suggestions. The vertical rise from the toilet output to the top of the loop is 48" ( the hose on the left side of attached image) . Tomorrow I will measure the distance to the waterline but as shown in the photo it is just below the deck line. The "Dry" mode is a new term for me and I will have to read up on that further.

Do you see anything right off in the image that sounds an alarm or that could improve the system ?
My vent line does not have a loop but run from the top of the holding tank along the underside of the deck and vents at the rear of the boat.

Thanks for your help

 

[Peggie Hall HeadMistress]

That's a LOT of hoses coming and going to and from somewhere...I'm gonna need a little help sorting out which does what. We can connect via private message to do that if you like.

My vent line does not have a loop but run from the top of the holding tank along the underside of the deck and vents at the rear of the boat
It's the toilet's flush water INTAKE that needs a vented loop, not the tank vent line. However, from what you just said, I strongly suspect your tank vent line is a lot longer than the optimal 5'...so we should discuss that too.
As for the "dry" mode...every manual marine toilet has a "wet" or "flush" mode and a "dry" mode. In the wet mode, the pump simultaneously pulls flush water in and pushes bowl contents out. In the "dry" mode, the flow of incoming flush water is blocked...pumping the toilet only pushes bowl contents out, it doesn't bring any flush water in.

Send me a PM...we'll get it all sorted out.

 

[woodster]

dare i say this in risk of waking Kermit up....nice new avatar pic

 

[Peggie Hall HeadMistress]

Thank you, sir...glad you like it. It had been 8 years since I'd had any photos done, thought it was time for new ones. I didn't want studio shots this time, so met the photographer on a pedestrian bridge over the Arkansas river on a chilly day this past February.

 

[LakeMurraySailor]

Ditto on the photo Peggie! Question: Where can I get a replacement "joker" valve and is there a rebuild kit for a 1973 Jabsco? And how is it /installed/changed?

 

[Peggie Hall HeadMistress]

It's way past time to replace the pump. Jabsco no longer offers service kits for toilets that old, but even if they did, it would cost you almost as much as a a new pump. However, it's unlikely your toilet pump is actually that old...compact manual toilets just don't last 40+ years. Even a Raritan PHII--rated best manual toilet in its class for at least that long--has only about 25 yr life expectancy, and that's only if it's kept well lubricated and rebuilt every 5-6 years.

And since Jabsco now builds toilets designed to be "disposable"...made in Mexico using materials sourced from China and other similar sources, I suggest you consider upgrading to the latest Raritan--the PH SuperFlush, which replaces both the PHII and the PHC--although it still uses the same pump. It even uses the same mounting bolt pattern as today's Jabsco manual Check it out on the Defender website: Raritan PH SuperFlush Manual Toilet at Defender

 

[woodster]

that is a neat looking head...but they waited to long in offering it for me ....mine is a good head (phII) and i will probably not upgrade unless it gets hit by lightning.....

 

[Peggie Hall HeadMistress]

You really don't have anything TO upgrade, Woody... 'cuz the new PH SuperFlush still uses the PHII pump. Keep yours well lubed, replace the joker valve annually and put a rebuild kit in it every 5-6 years and it'll last you at least 20 years.