VacuFlush Spitting Up

[VicTrawler]

I have a VacuFlush (Dometic brand) toilet (2012 install) that spits up when flushed. It did this since we bought the boat, then it stopped doing it for about three months, now it's doing it again.

It flushes fine, it's just that when the ball valve initially opens, it sprays the contents of the toilet upwards before sucking it down. It still flushes very quickly and effectively. We mitigate the problem by closing the lid before flushing, but it still creates a mess of the seat.

Has anyone had a similar problem? Any ideas on how to fix it?

 

[O C Diver]

When you flush, break the seal slowly. Once the level is starting to drop in the bowl, you can more quickly open it the rest of the way. A little practice will give you exellent technique, with no spitting.

Ted

 

[VicTrawler]

When you flush, break the seal slowly. Once the level is starting to drop in the bowl, you can more quickly open it the rest of the way. A little practice will give you exellent technique, with no spitting.

Ted

Unfortunately the mechanism is operated electrically, so there's no way to throttle it (that I'm aware of).

 

[O C Diver]

Unfortunately the mechanism is operated electrically, so there's no way to throttle it (that I'm aware of).

Oh, mine our maual pedal.

Wonder if reducing the vacuum level would solve the problem.

Ted

 

[HeadMistress]

This is the first time I've ever heard of a problem that isn't even mentioned in the trouble-shooting guide in the owners manual. But I do know it definitely shouldn't happen! Call Dometic tech support: 800-321-9886

 

[Conrad]

We have two on board, installed new in 2014, and there is no hint of spitting when we flush.

 

[Gordon J]

spitting up

We have two on board, installed new in 2014, and there is no hint of spitting when we flush.

As mentioned higher this happens with both my heads if I hit the pedal too fast. Must first break the seal and then continue the flush. Is there anyway to dampen the opening mechanism?

 

[bayview]

There is supposed to be vacuum in the line when you open the valve. Spitting sounds like pressure???

Do you hear strong sucking sounds immediately when operating the switch??

What happens if you turn off the pump and then flush. What happens if you drain all the vacuum with the pump off then flush? Put a piece of TP in a dry bowl and flush. Which way does the TP move?

 

[VicTrawler]

Oh, mine our maual pedal.

Wonder if reducing the vacuum level would solve the problem.

Ted

You nailed it. I googled how to do it and found a YouTube video: (

)

All I had to do was adjust the spring on the microswitch that determines when the vacuum pump shuts off. The switch is on the vacuum tank. I adjusted it to reduce the strength of the vacuum. Problem solved.

Thanks to everyone else for their quick replies and suggestions.

 

[rochepoint]

When the bowl is filled to much first and you just step fast on the pedal it will spit. If you gentle start the pedal down then open all the way it won't. We normally don't have a problem using little water before stepping on the pedal and then just hold the pedal down so the water running for 5 seconds.........

 

[bayview]

amazing that too much vacuum makes it spit. very counterintuitive.

 

[Capt.Bill11]

amazing that too much vacuum makes it spit. very counterintuitive.

I think it burps back when you have a lot of water in the bowl. As in it can't swallow it all at once.

Personally I'd rather not lower the amount of vacuum to fix the issue. Just adjust the amount of water the bowl holds.

It's always been my understanding that if the over all system is working correctly you should never have to adjust the spring loaded switch.

 

[VicTrawler]

Just wanted to provide an update for anyone reading this thread in the future. Adjusting the strength of the vacuum didn't resolve the problem - only temporarily - and having the vacuum that weak only compromised system performance.

I ended up changing the ball seal (the seal between the ball and the toilet) and all problems went away. I can't explain how that seal would cause the spitting problem, but it definitely needed replacing as it had become quite brittle. The manual says they should be replaced every three years - ours was four years old.

 

[VicTrawler]

Alright, ANOTHER update. Yes, the ball seal required replacing, but I still found the ball wasn't shutting completely.

I tore down the whole thing to the point where I could remove the ball, and I found that the cam (this part: https://www.environmentalmarine.com/kit-rotor-shaft-cam-4300-4400-311296/) was loose on the ball valve shaft. I inspected the cam and didn't see any noticeable wear. I then tried reinstalling it and putting a little more torque on the set screw that holds it to the shaft, and lo-and-behold, problem solved. There's no longer any play between the ball and the shaft, and the ball closes all the way.

No more leaks, no more splashing or spitting up. Everything's working as per normal.

I definitely didn't fix this the easy way, but I now know the toilet inside and out, so at least there's that.