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Dometic VT2500 vacuflush toilet


John and Liana Fox

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Your best bet is to try Lee sanitation, they know what they are talking about. It is controlled by a couple of microswitches, there is a little rubber diaphragm in the front of the tank that pushes on a little red(?) switch on the front face of the big unit in the picture, Most of the problems with holding a vacuum, cycling etc. are down to the loo itself, the 'ball' or the rubber seal sandwiched between the bowl and the base, As you can tell, I have one. In fact I have bypassed much of the tech stuff. I have put a switch directly to the thing so you switch it on, It springs to life, builds up a vacuum, use the loo, switch it off. Works perfectly.

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The switch just lives above the loo, fixed to the woodwork, I think I just cut into the positive wire, lengthened it to suit and put it back together, It still has its fuse on the main fuseboard so quite safe. All the joins are quite tidy and hidden behind the great big screwdriver that is used to stir the contents before flushing if it looks like it might clog the thing and alongside the wire coathanger that is used when it does clog......

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1 hour ago, pearley said:

Like Bee says, there are many things that can go wrong with the system. There are a few on here that have it and know all about its foibles.

So what are the symptoms of yours.

Pearley, thank you. I’ve checked micro switches and connections, which seem ok. When I switch on the power, the pump builds a vacuum and sucks fluid into the holding tank. The pump then stops. The green light does NOT come on, the yellow light stays on, and nothing happens If you press the loo foot pedal, apart from water coming into the pan, if you don’t turn the water supply off. If you take the 4510 holding tank off, the red light comes on.
what puzzles me is that the pump comes on for about 15 seconds when you switch on, and during this time you can make the pump switch on and off by putting your finger on the air pipe hole, with the holding tank removed and red micro switch pressed.  With tank fitted, water below the pan can be heard Slowly entering the holding tank, but I think this means the vacuum must be lost. After 15 secs, it won’t come on again. If you press the pedal, there is no suction, as the loss of vacuum has not triggered the pump. There must be a fault overriding switching on both the pump and green light.
All suggestions welcomed!

Edited by John and Liana Fox
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I saw you post on Facebook so had a look on here. I have fixed several of these in the past and have put information on here, so search for my posts, something there may help. 

 

I have some pdf files, but cannot see how to paste these in.

 

 

 
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38 minutes ago, John and Liana Fox said:

Pearled, thank you. I’ve checked micro switches and connections, which seem ok. When I switch on the power, the pump builds a vacuum and sucks fluid into the holding tank. The pump then stops. The green light does NOT come on, the yellow light stays on, and nothing happens If you press the loo foot pedal, apart from water coming into the pan, if you don’t turn the water supply off. If you take the 4510 holding tank off, the red light comes on.
All suggestions welcomed!

Remove the cassette. Put your finger over the hole in the vacuum tit (under the latch if you have one) then press the microswitch in and hold it. The pump should run for a second or two and stop. Keep your finger over the hole. The pump should not run again. It it does you have a vacuum leak in the pump.

 

The fact that the green light never comes on would imply either the PCB or the control panel at fault.

 

You say it sucks liquid into the tank but then say it doesn't suck out of the WC when pedal pressed. How do you know it's sucking liquid?

 

You haven't played with the two lock nuts on that lever attached to the actual pump, have you,?

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Hi Jonesthenuke,

Thank you! Could you email your pdf files to me at johnaefox@hotmail.com please?

best wishes,

John and Liana Fox

 

Pearley,

I can hear the water entering the holding tank and of course then empty it. I have not touched the lock nuts but can see the lever mechanism move and open the switch when I put my finger on the hole during those first 15 seconds.

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I think that it doesn’t come on again if you remove and reinsert the tank after that first 15 seconds, unless you switch off the supply, wait and then switch it on. I will check this in the next day or two when I go to the boat.

During the first 15 seconds when the pump is going, it turns off a second  after I pop my finger over the hole, and will do so repeatedly until the motor stops for good after about 15s.

Edited by John and Liana Fox
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It should run for around 40 seconds or so with an empty cassette before the pump cuts out.

 

Thinking about it, I would first get one of those springy drain cleaner to things and shuff it up and down the hose to ensure there is no blockage. The hose is only good for around 10 years with the internal diameter getting reduced daily due to buildup of uric acid and limescale making it much easier for blockages to occur.

 

As you have the docking station removed you can run the cleaner through from both ends.

 

With regard to the green light, it is very easy to get the connectors on incorrectly which gives interesting faults.

 

Have sent you a PM.

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We have identical same system and use a switch too.

 

Turn on switch, get a vacuum. Flush, regain vacuum until the unit stops itself, turn off switch.

 

Rejoice when you re-turn on the switch and the vacuum pump does not to need work proving the vacuum has held. Saves the pump cycling when you are trying to sleep. 

 

We found out of the various holding tanks we have, some hold a vacuum and one does not.

 

The two locknuts on the cam are quite sensitive and need fine trimming. I do recall having to change one of the microswitches.

 

The bog is great. When it works fine. I will remember Pearlys trick ref the cleaning out the small dia pipe.

 

Edited by mark99
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Our system is over 13 years old of everyday use as liveaboards. I replace the seals on the docking station about every 11 months, clean it and lubricate them regularly. 

 

The flush ball lasts about 4 years before it requires replacement.

 

It holds vacuum overnight with no problem.

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9 hours ago, John and Liana Fox said:

Pearley, good to know. Thank you.

Where do you get a full set of seals and other parts from, Pearley.  please?

I buy standard O rings, far cheaper than the Dometic spares.

 

The dimensions are as follows:-

 

Input pipe to Cassette base 0 by 6mm cross section

 

Valve in Cassette and matching spout on base, 39 mm ID by 3 mm cross section

 

Flange on cassette valve 60 mm ID by 3 mm cross section

 

Vent filter connections and pump outlet 14 mm by 1.5 cross section

 

Vacuum switch to cassette connection 13.5 by 2 mm cross section

 

Pump inlet connection 18 mm by 2 mm cross section

 

Cassette cap seal 46 mm by 5 mm cross section (this may or may not work as its a round seal and should be rectangular section.

 

All of these are in nitrile rubber for chemical resistance. I use Sealforce53 on Ebay (no connection to me, but have used them before, they seem to stock all sizes and give expiry/manufacture dates for each batch which gives me some confidence).. The seals can be bought in various numbers but 25 of each has cost me less than £20 including delivery.

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10 hours ago, WotEver said:

Wouldn't it simplify your calendar to do it yearly?

It would but it generally starts to leak vacuum at 9 or 10 months. A good clean and new grease keeps it going for another few weeks then I change them.

 

We could try keeping our legs crossed for longer.

1 hour ago, jonesthenuke said:

I buy standard O rings, far cheaper than the Dometic spares.

 

The dimensions are as follows:-

 

Input pipe to Cassette base 0 by 6mm cross section

 

Valve in Cassette and matching spout on base, 39 mm ID by 3 mm cross section

 

Flange on cassette valve 60 mm ID by 3 mm cross section

 

Vent filter connections and pump outlet 14 mm by 1.5 cross section

 

Vacuum switch to cassette connection 13.5 by 2 mm cross section

 

Pump inlet connection 18 mm by 2 mm cross section

 

Cassette cap seal 46 mm by 5 mm cross section (this may or may not work as its a round seal and should be rectangular section.

 

All of these are in nitrile rubber for chemical resistance. I use Sealforce53 on Ebay (no connection to me, but have used them before, they seem to stock all sizes and give expiry/manufacture dates for each batch which gives me some confidence).. The seals can be bought in various numbers but 25 of each has cost me less than £20 including delivery.

I've always used the genuine ones from Leesan. Are you using a normal O ring on the 'spout' rather than the original double one?

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The other spare which will save money on these toilets is the microswitch used on the cassette present and pressure switch positions. This is the item required from RS as a fraction of the Leesan price at  £4.23 plus VAT etc). These switches do wear out and cause all sorts of problems. http://uk.rs-online.com/web/p/door-interlock-push-button-switches/0575539/

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