Thetford Toilet Problem

Submitted: Sunday, Jan 05, 2014 at 10:28
ThreadID: 105691 Views:3404 Replies:4 FollowUps:7
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Hi Everyone,

Probably not the best query but have not been able to find the answer anywhere.

Have a 2009 Jayco Sterling Outback with shower and toilet. Problem is after free camping and moving on with the toilet cassette 2/3rds full there is a terrible odour inside the van when you stop travelling (not good). Have looked at diagrams and there saying there should be an outside vent fitted. The cassette has a vent underneath which when installed into position it opens into a cavity but this cavity has no hole to vent to the outside. Underneath the van the is a white round dome cap which I have removed to see were it goes and has hole to nowhere.
I am thinking this should have a hole through to the vent cavity, but I am not prepared to cut holes until I find out for sure.

You help with this issue would be appreciated.

Regards Allan
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Reply By: Notso - Sunday, Jan 05, 2014 at 11:17

Sunday, Jan 05, 2014 at 11:17
I've had a few Thetford Cassette toilets and I've never had a vent in any of them.

Is the rubber gasket damaged or out of place, the system should seal off when the slide is closed.
AnswerID: 523922

Reply By: MEMBER - Darian, SA - Sunday, Jan 05, 2014 at 12:14

Sunday, Jan 05, 2014 at 12:14
Haven't seen a vent of any sort on ours either - the waste tank seems to be a 'sealed' container once the slide hatch is closed - you must have a dodgy seal (they are a consumable item it seems) - one other possible cause is gas production in the waste tank, but correct use of recommended chemistry should prevent that.
AnswerID: 523925

Follow Up By: Member - Allan H (NSW) - Sunday, Jan 05, 2014 at 13:42

Sunday, Jan 05, 2014 at 13:42
G'day Darian,
Thanks for the reply.
When you say slide hatch your talking about the open and close slide operated from inside the van, not the slide that closes when you remove the waste tank.
FollowupID: 805518

Follow Up By: MEMBER - Darian, SA - Sunday, Jan 05, 2014 at 14:13

Sunday, Jan 05, 2014 at 14:13

This is the tank we have - the sliding cover at the top seems not to 'seal' anything, while the shutter mechanisminside the waste tank does all the sealing. That shutter mechanism is operating by a twisting movement of the adjacent green knob built into the tank; that is turned by the white handle inside the toilet cubicle, when the whole thing is back together. Putting a new seal on the shutter mechanism would be a great start in my view.... some vanners spray budget vegetable oil on that seal between uses, to keep in soft.... the pink Thetford flush tank additive is said to have silicone in it to enhance seal life.... crikey.... some of these stories could be true !THIS SITE (among many others) has a breakdown of spares for the Thetford toilets. I'm guess local van accessory suppliers will have them.
FollowupID: 805520

Follow Up By: Member - Allan H (NSW) - Sunday, Jan 05, 2014 at 14:45

Sunday, Jan 05, 2014 at 14:45
Just removed the tank and found what looks like a vent under the tank and slips over a hole when in position could you enlighten me with this. Thanks again
FollowupID: 805521

Follow Up By: MEMBER - Darian, SA - Sunday, Jan 05, 2014 at 18:20

Sunday, Jan 05, 2014 at 18:20
Yep - under the waste tank, on the floor of my installation there are two 'wells' with flip off covers - one cover has no features while the other has a sort of vent like structure. Neither of those two wells is vented anywhere; but there are mouldings in the well floor that may be hole cutting guides for other types of installations - motor home or marine maybe. All academic I think.... you must have a waste tank sealing issue... in 5 years, we've never had a toilet odour in the van (but there is always tomorrow :-o). BTW - those wells can get hold moisture - screws into my van's floor have rusted badly - why the builder didn't use stainless beats me.... there's another job for me.
FollowupID: 805536

Follow Up By: Member - Allan H (NSW) - Sunday, Jan 05, 2014 at 18:45

Sunday, Jan 05, 2014 at 18:45
Well that puts my mind at ease, no modifications needed. Looks like I will have to fit new seals.

Thanks so much for your time and your responses.

FollowupID: 805541

Reply By: oldtrack123 - Sunday, Jan 05, 2014 at 15:42

Sunday, Jan 05, 2014 at 15:42
Are you using any chemical to contol odours such as Sodium hyper per carbonate [Napisan]?
That should remove the odours generated
There may be a small vent just to the upper left of the bowl opening
This is operated by the bowl slide oping KNOB
It's purpose is releases gas preesure fro mindie the lower tank just before the BOWL slide opens
It may not be sealing when the BOWL slide is closed,v letting gasses continiously escape into the van

AnswerID: 523932

Follow Up By: Member - Allan H (NSW) - Sunday, Jan 05, 2014 at 15:58

Sunday, Jan 05, 2014 at 15:58
Hi Oldtrack,
Using Thetford lower tank chemical, maybe I am not putting enough water in the tank after the chemical to help neutralize the odour.
FollowupID: 805524

Reply By: Racey - Monday, Jan 06, 2014 at 10:58

Monday, Jan 06, 2014 at 10:58
Never had a smell in the van. Important to use chemicals, some better than others.
2/3's full = how many days? Do you have a policy of "no poo loo" they tend to smell more. A few solids give the chemicals something to work on. ^_^ No matter what they need to be emptied after 3-4 days.

To ensure the tank is sealed, when you empty it spay olive oil around the flap and seal. Use use only olive oil and it's available in spray cans at most supermarkets.

External vent fans were being promoted as after market items a few years ago, none of the reports I read convinced me to buy one.

If you wish to go down the "napisan" path, use the Aldi stuff in the purple container, it appears to have a higher active oxygen content. Otherwise stick to to the Thetford blue or green chemicals. We have tried a few of the home brews and so called environmentally friendly concoctions and have become very wary of their claims. It pays to read the contents very carefully to see what you are paying for. One tablet brand is nothing more than "napisan" compressed into tablet for which you pay a fortune.

AnswerID: 523966

Follow Up By: Grumblebum and the Dragon - Tuesday, Jan 07, 2014 at 08:26

Tuesday, Jan 07, 2014 at 08:26
Racey has got it spot on. Change the seals, use olive oil once a month and we also find the 'el cheapo' version of Nappisan is the best..... as in 34% versus 24% of the active ingredient (sodium Percarbonate) and one third of the price. The other tip is to M/T every three days regardless of how full.

FollowupID: 805592

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