Vacuflush toilet loosing vacuum

Submitted: Thursday, Feb 09, 2012 at 02:52
ThreadID: 127877 Views:2522 Replies:6 FollowUps:4
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Can anyone advise - our vacuflush toilet is not loosing water from the bowl seal, however the pump comes on at regular intervals of approx 15 min. We have decided it is the seals in the vacuum section - of which there are 4. Having picked them up today, we are ready to do the replacements. We have removed the tank, and looks like we will need to unscrew the whole unit from the base and remove to replace the seals - can anyone advise ?

Denice
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Reply By: Bobrovin - Thursday, Feb 09, 2012 at 03:47

Thursday, Feb 09, 2012 at 03:47
To get a good seal it is usually just a matter of giving the seals a good clean and a spray of silicon.
You should give the seals a quick wipe with a paper towel every time you empty the cassette and a spray of silicon on a regular basis.

If you have to change them it can be done without removing the base.
You should only need to replace 3 seals 15B, 15C, and 15D. as 15A is only the seal on the pipe.
15D is strait forward, for the other 2 you need to push the sleeve (no 20 on the Diagram ) back against the spring till it exposes the seals. Helps if someone else can hold it in for you while doing the changing.
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Follow Up By: Quicksilver - Friday, Feb 10, 2012 at 03:41

Friday, Feb 10, 2012 at 03:41
Thanks for your contact - had to remove complete unit as hatch door was not large enough for 2 people to work on the unit. ie: one holding back the spring.
Also we have a central ensuite, so the base station is under the kitchen drawers - so almost qualify now as a contorsionist ! David has successfully installed all new seals however the pump is still coming on albeit every 25 min now.

We are considering installing a switch to isolate the pump to the toilet without effecting water flow to other areas.

Have you got any other ideas ?

Cheers, Denice
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Follow Up By: Bobrovin - Friday, Feb 10, 2012 at 04:11

Friday, Feb 10, 2012 at 04:11
There maybe a build up of gunk in the connection tube in the cassette. Push the large plunger in and clean the surface that mates with the new seals. A spray of silicon in here is a good idea as well. Same with the little plunger.
Also a good idea to thoroughly clean and rinse the cassette . I usually use nappy san, flushed through the system and letting it soak for a while.
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Reply By: Free & Easy - Friday, Feb 10, 2012 at 07:20

Friday, Feb 10, 2012 at 07:20
What Silicon Spray do you use. The 3-IN-ONE Professional Silicon Spray Lubrication from WD40, is that OK? Says its OK for rubber but has a * that says prolonged use on rubber not recommend.
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Reply By: kenmarg - Friday, Feb 10, 2012 at 22:14

Friday, Feb 10, 2012 at 22:14
hi denice. we also have a dometic vacu flush. i didnt think you could use a silicone spray, ( the propellent in the can is not good for the seals ) dow corning make a silicone grease,that helps the o ring form a seal. i use this grease,and even if the seal is a bit worn,it will form a seal to hold the vacume. if you have the base station,out from the van make sure,you change the filter. as dometic has now ceased making this model, make sure you buy a extra set of o rings. regards. ken brown
AnswerID: 583788

Reply By: gottabjoaken - Friday, Feb 10, 2012 at 22:58

Friday, Feb 10, 2012 at 22:58
Have you checked the seal in the cap for the tank?

If you screw the cap on too tight, the seal can be extruded and form tatty bits that will interfere in the seating and make a very slight leak.

The cap only needs to be "finger tight" with a good seal, gradually increasing in tightness as the sealing ring wears. You can't buy a seal for it, it is a soft plastic ring that seems to be fixed in the groove in the cap.

Try trimming the tatty bits off with a very sharp box cutter, without nicking the black plastic seating at all. Otherwise buy a new cap from most caravan parts stores or online (cheaper).

Ken
AnswerID: 583789

Follow Up By: grumpyolephartz - Tuesday, Feb 14, 2012 at 01:53

Tuesday, Feb 14, 2012 at 01:53
Some times you can find the cap off a 20 litre chemical drum that fits the Dometic toilet. I am aware that some people have used some silicone to make up a seal, and glad wrap to stop it sticking to the tank. Glad wrap itself can make a temporary seal.
Regards from us grumpyolephartz, mostly John, but may be Heather

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Reply By: Wherrol - Saturday, Feb 11, 2012 at 06:14

Saturday, Feb 11, 2012 at 06:14
Hi Denice,

Dometic said we should use Dow Corning High Vaccum Grease on our Vaccuflush Loo.

Cost is about $40 a tube.

It takes one whole tube to re-do all the pipe ends.

Cheers

Allan and Sharon
AnswerID: 583790

Reply By: grumpyolephartz - Tuesday, Feb 14, 2012 at 01:57

Tuesday, Feb 14, 2012 at 01:57
The Ball Flush mechanism in this model can also go "off-centre" and you can fail to raise vacuum sometimes. I know that some people have put a screw into the 'axle' at the pedal end to stop it from pulling away.
Regards from us grumpyolephartz, mostly John, but may be Heather

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Follow Up By: Quicksilver - Friday, Feb 17, 2012 at 08:38

Friday, Feb 17, 2012 at 08:38
For the information of all those who kindly came to our assistance ....

We eventually located the area where the leak was, however we are not exactly sure which of the items replaced were the cause.. We found the leak in the piping between the suction pipe that protudes into the cassette, and the vacuum pump.

The method we used to pinpoint the leak was quite simple. On the bottom right hand side of the cassette docking station, there is a switch. When this switch is pushed in, the vacuum pump operates. Whilst keeping the switch pushed in, I held my finger on the hole located on the bottom of the suction pipe (mentioned in paragraph 1) the pump switches off. When this occurs we are holding a vacuum in the small section of piping. If there is a leak in this piping, the pump will switch off and on intermittantly, as quickly as the vacuum is leaking. (as ours did) If there is no leak, it will continue to hold the vacuum.

We replaced the O rings in this section and we also turned over one of the white rubbers, located in the housing that the pump attaches to.

So unfortunately we don't know which of the above was the culprit. All the O rings looked ok, however the white rubber that we turned over had a mark on it - so it could have been this.

Over a 24 hr period we are still holding a vacuum without having the pump come on.

We'd like to thank everybody for their imput. It is great to be associated with a club where assistance is forthcoming so readily when help is needed.

Kind regards,

David & Denice
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