Black tank smell in MH (1 Viewer)

[peterc10]

That is just so comforting to him.

Thanks. I thought so to.

 

[DavidG58]

I now think I have solved the smell problem and the mystery of the vent

As said above I gave some thought to the 'can't get at anything' and went back to investigate and removed a couple of panels I didn't even know were there

exposing the black tank top, rather neatly mounted right next to an air intake for the Alde system

checked the top cap, that was and still is fixed tight

then found a corrugated hose leading out of the top of the tank, not sure if this fitting was ever sealed, but it is certainly not now, loose to touch and removed with no effort, certainly enough gap around to allow odour release

I am slightly grateful that it wasn't a welded connection and now broken, so for ease I have smothered the pipe with petroleum jelly and pushed back in, now has an airtight seal.

But now I have question regarding where does this hose (which now must surely be the vent pipe) go to

it disappears off to the other side of the garage behind fixed panelling

reappearing in the middle of this lot, a combination of Alde and air con systems, then seeming to go upwards again

Now at this point I feel the need to bow down and apologise to much wiser earlier contributors who said it must go through the roof, we did look at the following mushroom type fitting and ruled it out, but it is now ruled right back in as a roof mounted air vent connected to that same corrugated pipe, but now back on the other side of the MH for no obvious reason and the tube totally hidden in void areas between cupboards, it would literally need full dismantle to change the tube

note the odd shaped corner, that triangle shape caries the pipe to the roof

while there I have also resolved another annoyance, the clean water tank is more often than not virtually impossible to get water into without forcing a pipe right down the tube. For reasons only Hymer would know, the tank is on the offside and the filler on the nearside (reverse logic for the vent pipe thinking about it) the inlet hose has a massive dip in it probably creating an airlock, I am going to lift it up and fix in place at least horizontally tomorrow

Feel fairly chuffed albeit a little disappointed with myself it has taken three years to get to this stage

 

[DavidG58]

The white thingy with the O rings looks like an air admittance valve. If it is then it is there to let air into the sealed system to prevent a vacuum forming, but not let air (and therefore bad smells) out. If you are feeling lucky you could always try blowing and then sucking. You should be able to blow air in, but not suck any air out. But if I am wrong you could end up with a mouthful of s**t. Well at least its your own.

thanks Peter, anything to remove the taste of Kent water (I don't think so thanks)

not really sure what function it will serve now I have found the wider bore vent pipe to the roof, wont that do the same ?

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[peterc10]

not really sure what function it will serve now I have found the wider bore vent pipe to the roof, wont that do the same ?

I don't know, it may be allowing air into some other part of the system?

 

[Allanm]

Well done with your perseverance. It looks a very complicated system, ours is just a toilet with a flap that opens and drops the crap into the black tank. To empty, you connect the macerator and hose and open a blade valve. When that's done, open the grey water valve which flushes everything through. The vent goes straight to the roof from the top of the rank. No electronics.
Just a thought though, do you have an extractor fan in the bathroom? They are well known for sucking bad air up from the toilet when you flush, unless there is no direct access to the tank as the waste is flushed away.

 

[berni109]

Just been having a read through your posts- nothing like a good s**t thread.
Now there has to be an input output and vent for the system to function all of which u seem to have. U also have a macerator pump and air admittance valve which all work as u would expect because the waste gets into the tank and u don't have water in the bowl siphoning out. So the vent will be at the highest point in the system at the top of the tank which u now seem to have found. What is the small pipe in the photo next to the black drain. Get an £8 quid USB camera with a few meters of lead and feed that it into the vent to see where it goes and what condition its in.

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[DavidG58]

@Allanm

Thanks, no extractor and I have more or less proved to myself that even without water in the bowl it is sealed by the water in the way the tubing is routed to the black tank.

we also always refill the bowl to totally eliminate this risk

 

[DavidG58]

@berni109

thanks, no idea about the blue valve thing, I will have a good look tomorrow before refitting the panels, hopefully if I can see where the black pipes goes to it will be obvious

 

[funflair]

@DavidG58 I have read right through and although I am mightily impressed I am also slightly dissapointed, is this a new David who gets stuck in a fixes things without spraying the neighbourhood in high pressure bio hazard.

Martin

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[DavidG58]

thank you Martin

I more or less managed, I emptied the tank before starting, then promptly took the rubber boot cover off the chopper blade without flushing!!

then learnt that the stainless steel bracelet I wear to ward off rheumatics (I think it works) creates a dead short when touched across the incoming terminals on the control board

still learning

 

[DavidG58]

What is the small pipe in the photo next to the black drain. Get an £8 quid USB camera with a few meters of lead and feed that it into the vent to see where it goes and what condition its in.

with a panel removed it became more obvious, the hot and cold water pipes change to the rigid black for some reason in the garage area, still quite sure what function this fitting would have but the one next to it is our cold water dump option, presume this does similar but maybe for hot water, although I would expect the be nearer the Alde system

and can confirm smell issue resolved, it must have been coming out the ill fitted vent connection on the tank top

thank you all for much appreciated input

 

[DavidG58]

Not really sure about resurrecting such an old thread, but why not, third time lucky

Also confirmed a tea time discussion with Bev, this thread started in 2013, almost 4 years ago to the day and we had the problem already, so have lived with this odour issue for four year and some but it is now definitely getting worse

having confirmed the roof vent is the black and possibly combined with grey tank air vent, and having got a recurrence of the odour issues, I decided to have a closer look at the vent

above though is as far as I got before ringing @Terry for moral support and manual back up options

I should add that despite 'sealing' the black tank outlet myself last year, it had to be done properly by Terry last year a few weeks later

I cant get any further than removing the screws, the vent top is firmly stuck to roof, possibly has a lock nut and any more pressure to try to remove it could cause serious damage, certainly if done by me

But what I could do as run a hose pipe into this vent pipe, then go and listen for water trickling into black and maybe grey tanks

ran hose for a minute turned off to listen, nothing, got right up close to back tank, still nothing, then went inside to wardrobe where the vent pipe goes up behind in totally sealed void area. The wardrobe floor was soaking and water was running down the wall

So what I now know pretty much for certain is the hose is either split, or has become disconnected, both seemingly unlikely, or maybe never actually attached from new

Now need to get the top off, or maybe cut an access to the void area from the wardrobe or top locker on other side, then refit or replace the vent outlet, maybe to outside wall if all else fails

Hence the Terry input

Further update tomorrow, unless Terry reads this and heads off for next trip a day early

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[TheCaller]

Commiserations.

I know they say 'it never rains but it pours'. but I don't think you are supposed to do the pouring yourself.

On the plus side, it looks like you have tracked down the root of the problem.

 

[DavidG58]

Right, time to wrap this one up, with the help of @Terry , when I say with the help of, really I must thank Terry for 99% of the knowledge and ability, I had at least removed four screws though and looked at it from different angles

Terry has put paid to the pong prob, a truly poor design feature by Hymer

I think it would only apply to those fitted with black tanks, unless grey tanks also vent to the roof??

Flexi hose goes up to roof through complicated route and boxed in to make it really fun, when Terry got the mushroom thingie off the roof the hose was clearly never attached well, if at all, there was only about 10mm of pipe through the roof section and no sign of any adhesive

Terry fabricated an extension refitted it all, resealed, flushed, no pong

Top man Terry, yet again, that must be the 5th job you have done for me, that's just what I can recall

Thinking back we had a smell issue on our very first trip out, I am now pretty much convinced this hose had fallen off or never been connected from new, previous owners only did 2100 miles in three years, it had got worse recently but hopefully now put to bed once and for all

 

[Puddleduck]

Having read through all that and only realising part way through that the thread was so many years old I am now really pleased that out last two vans have had cassettes Not nearly as much to go wrong with a cassette and easily replaced (but not cheaply) if it ever becomes necessary.

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