Head Back-fill

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Steve

I recently purchased a boat with an electric head. The problem is that it never seems to flush. The pump pulls water into the bowl but not enough to get a flushing action. This means that after removing the waste, the bowl stays full of water, almost to the rim. Any suggestions?
 
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Peggie Hall/Head Mistress

It doesn't work like a household toilet...

Water IN has nothing to do with whether it flushes...the intake pump and the discharge pump are two separate pumps...it should should flush even if no water is coming in. Water should not come in any faster than it goes out. What you SEEM to be saying that waste IS flushed out, but the bowl is filling up with water again. What make/model is the toilet? Do you have an owners manual for it? Does the intake pump continue to run after you take your finger off the button? Is the toilet below the boat's waterline?
 
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Terry Cox

SIMILAR PROBLEM

Steve, I had a similar problem with electric heads on my P42. Check the archives for my earlier article. Mine was due to a plugged holding tank vent scupper. The back pressure prevented the water to be pumped out of the bowl and into the tank. Terry S/V Belle-Vie
 
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Peggie Hall/Head Mistress

Not sure it's the same problem, Terry

He SEEMED to be saying his toilet is filling with clean flush water, not backing up. I need more details...and a couple more questions occurred to me overnight... You may be onto something, but 9 times out of 10 sluggish discharge is due to low voltage to the toilet. How far is the toilet from the battery? Is anything else on the same circuit? Has he checked the battery to make sure it's putting out at least 12v and the toilet to make sure it's getting at least that much? Is he sure he used the right wire size for the distance from the battery (size is determined by round-trip distance, not one way)?
 
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Terry Cox

SAME SYMPTOM

Peggie, it seems my toilet behaved the same way when I had the plugged vent scupper. The bowl would fill with fresh water, but the pump would not discharge the bowl contents into the tank. It would just swirl around in the bowl. Terry
 
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Terry Cox

LET US KNOW WHAT YOU FIND OUT...

Steve, Peggie makes several good points about the amount of juice feeding the toilet. Trouble shoot each part of the toilet until you fix the problem, and let us know the results. Terry
 
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Steve

Head Back-fill (cont.)

Peggy, You are absolutely correct. Waste IS flushed out, but the bowl is filling up with water again. I can answer your 3rd question (NO) but I will need to get back to you on the 1st and 2nd 4th on Thursday when I can get back to the boat. Thanx to all who replied, even Dan :) Also, in the meantime, I will check the voltage to the pumps, esp. the discharge. And the vent. What make/model is the toilet? Do you have an owners manual for it? Does the intake pump continue to run after you take your finger off the button? NO Is the toilet below the boat's waterline?
 
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Peggie Hall/Head Mistress

Be sure to post the answers--WITH the questions!

Mine is not the only inquiring mind that wants to know! Once I have those answers, I'll have a better idea of what's prob'ly causing your problem.
 
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Steve

Head Back fill (redux)

Peggy, I have answers to your questions now: What make/model is the toilet? It's a Groco toilet that was converted from manual to electric at some time. Do you have an owners manual for it? Nope. Does the intake pump continue to run after you take your finger off the button? NO Is the toilet below the boat's waterline? This question is tougher to answer than I thought. The bottom of the toilet appears to be at or above the waterline. If open the raw water intake only slightly, it seems to flush better. However after flushing, the head slowly refills to about 3/4 full. One problem I discovered is that the raw water intake is not looped and vented. Could this cause the problem?
 
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Peggie Hall/Head Mistress

If the water is clean...

That is, you're sure it's flush water, and not waste back up...it very well could be that your problem is simply water outside the boat seeking its own level inside the boat (rising through the head intake). A vented loop would solve the problem. However the vented loop MUST go between the pump and the bowl...if you put it between the intake thru-hull and the pump, it'll interfere with the toilet's ability to prime and can "fry" the intake impeller. The only toilet Groco makes is the Model K, which is about $800...they did make the model EB (discontinued), but it's about $500... and since it's unlikely that anyone would have spent that much, I suspect what you REALLY have started life as a Groco Headmate (manual) that a previous owner converted to electric with a Jabsco conversion kit. Check the Jabsco website (http://www.jabsco.com) to see if their conversion kit looks like your toilet. If it's not, check it against the Groco toilets at http://www.groco.com Once you know what your toilet really is, you can get a manual for it and find out also find out whether it's adequate wired...'cuz as I mentioned in a previous reply, 99% of slugglish flush problems are due to low voltage. That can be due to a failing battery, the wrong wire size (wire size is determined by the round trip distance from the battery, not just one way), corrosion at the connections, Meanwhile, check your holding tank vent to make sure it's open--that your problem isn't a pressurized that's backing up. The first place to look is the vent thru-hull...that's where most blockages occur--this time of year, it's often a dirt dauber nest. Otoh, if you've opened the deckfill and didn't get a spew, that answers the question: the vent isn't blocked. If you haven't, I don't recommend doing so until you ARE sure the vent is open. Bottom line is, there are a number of possibilities--from blocked tank vent to low voltage to water rising in the intake. You're just gonna have to eliminate the possibilities till you find what IS causing it. Except for the tank vent, you'll need the owners manual--or at least the electrical specs and and exploded drawing--to find what IS causing the problem, and then cure it without causing new problems. Till you do find it and fix it, keep the intake seacock closed except when the toilet's in use. Don't restrict the water flow in during flush or try to flush without bringing in any water, 'cuz that can fry the intake impeller.
 
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