Dometic Vacuflush Constant Cycling

[mark99]

Anyone had this issue?

 

I adjust the rocker but it still cycles. Think the vacuum switch and rocker may be worn.

 

Trouble is, they discontinued spares iirc

 

[pearley]

Vacuflush cassette system?

 

[jonesthenuke]

Constant cycling is usually a vacuum leak. First thing to check is whether the water empties from the bowl?

 

The microswitches can be replaced, but do not buy from LeeSan as they are expensive, much cheaper from RS.

 

[Mike55]

You also need to periodically grease the O-rings that create the seal between the cassette & the docking station. Use silicon grease. Not a pleasant job,  but necessary. Wear plastic gloves. Also check the cap on the cassette is screwed on tight and the seal is clean.

[blackrose]

Yes the connection between the main shit pipe from the toilet going into the back of the docking unit is a nasty one. It's sealed with a big fat o-ring. If air is getting in there and you need to regrease the o-ring make sure you lay plenty of old cloths or plastic bags down. Check everything else first!

 

You have switched the toilet off haven't you? If you just let it cycle it will prematurely kill the vacuum pump.

 

Do you want some o-rings for that toilet? I think I've got a whole set I'm never going to need. PM me with an address and I'll send them.

Edited May 9, 2023 by blackrose

[mark99]

20 hours ago, pearley said:

Vacuflush cassette system?

 

Yes Pearley

13 hours ago, blackrose said:

Yes the connection between the main shit pipe from the toilet going into the back of the docking unit is a nasty one. It's sealed with a big fat o-ring. If air is getting in there and you need to regrease the o-ring make sure you lay plenty of old cloths or plastic bags down. Check everything else first!

 

You have switched the toilet off haven't you? If you just let it cycle it will prematurely kill the vacuum pump.

 

Do you want some o-rings for that toilet? I think I've got a whole set I'm never going to need. PM me with an address and I'll send them.

 

 

Very kind of you sir; but I have lots of spares - just not the vacuum switch/rocker. This is the unit that's faulty. I can get it to work (and holds a very good vacuum) but it soon goes out of adjustment (two chrome nut adjuster)

16 hours ago, jonesthenuke said:

Constant cycling is usually a vacuum leak. First thing to check is whether the water empties from the bowl?

 

The microswitches can be replaced, but do not buy from LeeSan as they are expensive, much cheaper from RS.

 

 

The water stays there, the vacuum is good and holds all day. Seems the plastic lobe on the "rocker" is just worn away.

[pearley]

As others had said, firstly us the bowl holding water? Secondly, is it a leak on the various cassette seals or on the docking station. With the cassette removed block the hole on the vacuum tit (top centre) and press the microswitch in (bottom right) The pump should run for a couple of seconds and then stop. If it doesn't recycle then fault is cassette, if it runs again or fails to stop then fault is in docking station. 

You do sometimes get a bit of effluent stuck under the non return valve which causes continual cycling. If you need to strip the pump I have instructions.

I sorted the seal that Blackrose mentions by fitting a rigid support for the pipe so it couldn't move.

 

Previous post whilst I was typing.

Edited May 10, 2023 by pearley