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Post Info TOPIC: Keeping water tank breathers clear


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Keeping water tank breathers clear


As you pump water into your caravan tanks the air must escape in order to allow the water to fill the tank, to this end all tanks have breather pipes and in many vans these pipes terminate in the filling nozzle  area, in my van that is a small (5mm) hole at the top (12 O'clock) position of the fill inlet, you'll need to bend low and look up to see it.

One issue with this small hole and pipe is that it blocks up easily with dirt and/or insects and can be hard to clean. It occurred to me that there is some simple regular maintenance we can do to help keep it clear:

When filling with water you will hear a gurgling noise some of which is water flowing into the tank and some is air flowing out; put your thumb over the breather hole attempting to totally block it, if you have blocked it the gurgling noise will change noticeably. Keep your thumb there for about 10 seconds and then quickly remove it, you'll hear another noise change and feel a small jet of air if you hold the back of your hand near the breather hole.

By blocking the breather when the tank is filling the air in the tank is compressed by the incoming water and when it's suddenly released it sends a (relatively) high pressure stream up the breather pipe hopefully clearing some of the muck in the process. Do it a couple of times each time you fill, it's not a perfect solution but it will help to keep the breather clear.



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The breather hole should be at least 10mm minimum diameter to work effectively.
Cheers,
Peter

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Peter_n_Margaret wrote:

The breather hole should be at least 10mm minimum diameter to work effectively.


Damn!

I shall immediately sell this caravan and make it a top priority when purchasing a replacement to ensure it has 10mm water tank breathers.

How could they unleash such poor quality upon us!?

Where is the ACCC when you really need them!?



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"I beseech you in the bowels of Christ think it possible you may be mistaken"

Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland



Guru

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I think that is pretty helpful advice Mike. Filling up the tanks in my van is akin to watching the grass grow if I want to fill them at least close to capacity. I usually put the hose as far down the inlet as possible and just have the water running at a bit more than a trickle whilst I stand there checking my fingernails and pondering the meaning of life.

I will give your idea a go. Nothing like bonding with your caravan with a bit of water tank flatulence to ease the pressure of everyday life.

Thanks.



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Guru

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Hi Dmaxer:

It sounds as though your van's breathers may be blocked, if that is the case my suggestion won't help. If you don't hear a change of sound then they probably are blocked.

To unblock them try a length of galvanised wire gently inserted into the breather for as far as you can or maybe inject some household bleach into the breather hole (use SafeColes cheap homebrand bleach) a few times over a week or so?



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"I beseech you in the bowels of Christ think it possible you may be mistaken"

Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland



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I always open the kitchen and ensuite sink taps.  It definitely makes a difference.



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Some time ago, my rear water tank had to be filled slowly or the water would run out the fill point. I found the breather pipe was squashed a little at a couple of locations, by some cable ties. Removing the tight cable ties and making sure that there no kinks has relieved the air restriction problem, and filling is much faster. My breather outlets have smaller plastic gauze over them so larger bugs etc cannot enter.

I find though, that when the tanks are full, the splashing of the tanks while moving, tends to put water into the breather pipes. The breather pipe to the rear is undulating so water can get into the "valleys" of that pipe. If I don't blow that water back into the rear water tank, the van's pump has trouble withdrawing water from the rear tank. Pretty easy fixes for me.

Bugs and/or dirt would be harder to clear.



-- Edited by watsea on Sunday 17th of April 2022 12:03:24 PM

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Senior Member

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Would it perhaps be viable to re-route the breather in a similar fashion to that used by off road vehicle for diff and gearbox breathers, to a higher point, more easier accessed and topped with some sort of a filter system?

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Senior Member

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I haven't experienced any breather issues to date, but I have found a simpler way to fill my tanks without taking off the external filler caps. I modified the plumbing so that the 'mains' water can be re-directed back into the tanks by reversing the flow into the tanks via the take-off tubes. So filling the tanks is accomplished by operating one 'filling' valve and selecting which tank (valve) to put the water in. The gurgling (and gauge) tells me when the tank is full. It works well because I don't have to go outside at all to fill tanks prior to breaking camp and moving on. It is a real time saver.

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Guru

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I have ordered a swarm of 9 mm wasps. That will fool em.biggrin biggrin

Jokes aside, I had a van that wasp mud in the breather and what I did was close all the taps in the van and fill the tank so that the water level was to the top of the filler neck.

I left it and went and had a beer and took this time to read the Aust Standard item 1 2 ZZa which referred to the size of the breathers in caravan water tanks.

Anyway after a short time the wasp mud had been soaked by the water and I then got a tea towel and wrapped it around the water hose I was using to fill and stuffed it into the filler neck so it formed a poor but effective seal and turned the tap on and with that the breather became free.

Damned waspsbiggrin biggrin



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Rob

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Newbie

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Place a male tap fitting on water tank drain tap. Connect to mains water tap, tank can be filled very quickly. You can also run water through filter at the same time if you wish.

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good advice mike 



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Guru

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Be aware that by "pressurising" poly water tanks there can be a risk of splitting the tank at seams or take off tube/s - a simple 1 meter head of water in a 12mm tube can apply a lot of force to an enclosed/blocked tank.

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Ah ha! Thanks Possum. Good that there is at least one other person in the world that understands basic physics. I've posted similar warnings over the years but... The other effect of even mild overpressurisation is a water tank sitting on the road and flimsy construction being blamed for ripped out screws and torn straps

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Guru

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So when the breathers are blocked with dead insects, mud etc how come we're not surrounded by exploding caravan water tanks when people attempt to fill them?

Come to that where do I find the pressure specification for these water tanks.

Come to that again; when I fill the tanks in a valley, with blocked breathers, how come they don't explore when I drive up a mountain?

My caravan has two 100L water tanks; when they are half full and I tow the caravan they are subject to the stress and random localised pressure of 50kg of water smashing around inside them, they seem to handle that OK?



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"I beseech you in the bowels of Christ think it possible you may be mistaken"

Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland



Member

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Yes  I had the awful slow fill issue so i asked my service provider to fix it and he shortened the breather hose and tacked them  to the underside of the van  no issues now!



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JohhnyM



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Basic physics 101 will answer all your puzzlements Mike. Happy to warn, but can't be bothered educating the terminally skeptical. But to save you some angst, Atlas Tanks, arguably the leader in RV tanks albeit at a leading price too, have this to say ***"Pressure Tested Each and every Atlas Tank is pressure tested to 2 metres of head. Testing by this method assures the tank can withstand a much greater pressure than it will experience in normal service conditions." " 2 metres is about 2.8psi so they don't have a lot of faith in their tanks ability to withstand deliberate or ignorant overpressure. However, the main problem is not that tanks will burst, but that mounting straps and floor and furniture above the tank can break.

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Guru

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It use to be a real pain in the backside, to fill my original fresh water tank, as I had to go very slow or have water spitting back at me

When I decided to put an extra tank in, the rough sketch below, shows how I did it

I now have no problem in filling with the pressure of the garden tap, and I do have the original filler cap open, to stop the tanks pressurising

Water tank filling.png



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Tony

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