Dometic Vacuflush toilet won't stop pumping. Do I need on of these?

[jymbee]

Toilet works fine, flushes ok and seals tight after a flush. But, the green light doesn't come on and it just keeps pumping. Lately it does work normally on and off, but not reliably.

Done quite a bit of searches and it according to things I've read we might well need a placement part like this. Just thought I'd run it by others here to see if that makes sense or if perhaps there's some other possibilities we should look at.

Also, how difficult might it be to replace this part if it's determined that's what we need?

 

[RRR]

The vacuum switch is fairly reliable but they do fail on occasion. That would be the last thing I would look at.

First how old is the system and what kind of use? Does the bowl hold water? If not start there. Second most common is bad duckbill valves, and/or ruptured bellows. Bellows will let you know as you will have a brown puddle around/under it. My guess is you need to rebuild the system

For a much better info go to VacuFlush: Get To Know The System - VacuFlush Troubleshooting - Marine Sanitation & Supply and VacuFlush: Get To Know The System - VacuFlush Maintenance Kits - Marine Sanitation & Supply

They also are fast shipping for parts and have phone help. Don't by "Will Fit" parts from unknown suppliers. They have QC problems.

Rebuilding the system isn't a huge job but depending on the location it can be ugly.

 

[Tom]

Toilet works fine, flushes ok and seals tight after a flush. But, the green light doesn't come on and it just keeps pumping. Lately it does work normally on and off, but not reliably.

Done quite a bit of searches and it according to things I've read we might well need a placement part like this. Just thought I'd run it by others here to see if that makes sense or if perhaps there's some other possibilities we should look at.

Also, how difficult might it be to replace this part if it's determined that's what we need?

Having dealt with Vacuflush toilets on boats for 30 years, I'd say there would be two things to check first (assuming, as you said, the toilet itself seals):

1. Occasionally, a clamped hose might be leaking a small amount of air; Just hand tighten all the hose clamps.

2. A duckbill valve in the vacuum pump might be leaking &/or have a piece of TP preventing the valve from fully closing.

 

[jymbee]

The vacuum switch is fairly reliable but they do fail on occasion. That would be the last thing I would look at.

First how old is the system and what kind of use? Does the bowl hold water? If not start there. Second most common is bad duckbill valves, and/or ruptured bellows. Bellows will let you know as you will have a brown puddle around/under it. My guess is you need to rebuild the system

For a much better info go to VacuFlush: Get To Know The System - VacuFlush Troubleshooting - Marine Sanitation & Supply and VacuFlush: Get To Know The System - VacuFlush Maintenance Kits - Marine Sanitation & Supply

They also are fast shipping for parts and have phone help. Don't by "Will Fit" parts from unknown suppliers. They have QC problems.

Rebuilding the system isn't a huge job but depending on the location it can be ugly.

Appreciate the input and informative links.

Given the description of Duckbill valves from one of the sites you listed, this does not seem to be the likely issue since, as I stated previously, the vacuum holds fine until the next flush.

Duckbills in the vacuum pump are what hold the vacuum on that end of the system. Once they have worn out they are not capable of holding the vacuum. Replacement is needed. They have about a 3-5 year lifespan, depending on use

Bellows? Long painful back story there. Very briefly, as I posted here back at the time, we experienced a foul odor that I first attributed to a leaky black tank. Dealer in Houston looked at it and said we needed a new toilet system (pump, valves, etc), parts would take over two weeks, and cost would be over four thousand bucks. Uh... no thanks.

Called Dometic and described symptoms and they said it was absolutely the bellows. However the part was very hard to find and after many searches, the site you listed marinesan.com/ had several. Highly recommend that outfit. Bought the part and a local shop installed it for a couple hundred bucks.

Back to the Vacuum Tank Switch Kit, I wonder if this is something that could work off & on? Today, as these things seem to go, all seems to be working normally. Previously, no matter how long we left it pumping, it never did the green light and stopped.

We also dumped a pretty full black tank the other day. Wonder if this somehow could have cleared some kind of obstruction. Obviously I know little to nothing about the operation of this particular system.

 

[jymbee]

Having dealt with Vacuflush toilets on boats for 30 years, I'd say there would be two things to check first (assuming, as you said, the toilet itself seals):

1. Occasionally, a clamped hose might be leaking a small amount of air; Just hand tighten all the hose clamps.

2. A duckbill valve in the vacuum pump (output side) might be leaking &/or have a piece of TP preventing the valve from fully closing.

Thanks Tom. But in our case, the seal holds just fine. IOW, after flushing, it just keeps pumping and does not stop with the green light coming on. At times we neglected to turn the pump off manually and it would run indefinitely.

So what we've done is after flushing turn the pump off manually. The seal holds fine indefinitely as evidenced the next time it's flushed. It's as if the bowl is saying, "Hey, enough already I'm sealed!" but whatever is supposed to stop the pump is not listening.

Also as I described in a response above, it seems to be an off & on situation. Lately, its starting to work normally at times.

 

[Tom]

Thanks Tom. But in our case, the seal holds just fine.

Yes, I thought I acknowledged that in my prior reply. My two suggestions apply when the toilet seals just fine, as yours does.

 

[RRR]

I would call MarineSan and ask them about the sometimes working.

I agree with your idea that it might be the switch. I Have fiddled with the pressure switch, turn it about 1/8 turn till you see some results. In to raise pressure, out to lower.

 

[Tom]

Toilet works fine, flushes ok and seals tight after a flush. But, the green light doesn't come on and it just keeps pumping. Lately it does work normally on and off, but not reliably.

Done quite a bit of searches and it according to things I've read we might well need a placement part like this. Just thought I'd run it by others here to see if that makes sense or if perhaps there's some other possibilities we should look at.

Also, how difficult might it be to replace this part if it's determined that's what we need?

Just curious if you got it fixed.

 

[jymbee]

Just curious if you got it fixed.

This toilet is obviously messin' with me. After my original post things started working normally. Flush, pump... pump... pump... green light/STOP. That lasted for a couple days but now, back to the same thing where it won't stop pumping even though the seal was solid.

We're winding down our current travels and will be headed back home today. As it's not a show-stopper given we can just turn the pump off after flushing, I'll wait until we get back to investigate further.

I guess that given it works sometimes and not others, that points to the possibility of this control device starting to fail?

 

[boatbuilder]

I have worked on a lot of Vacu-flush systems on boats and have never changed out the vacuum switch. My first guess would be the duck bill valves in the diaphragm pump. it doesn't take much for them to leak. Could be deposit build up, rubber getting stiff with age, etc. I always started with flushing several full(and I mean full) toilets of water through the system. It cleans the system out if you have to disassemble it and also fixes the problem about half of the time.

 

[SC5thWheeler]

I had a different issue with mine and this video from the manufacturer was helpful to me. He walks through the whole system and shows what could go wrong, etc. and how to fix it.