Grey Water backup

[Guest Alf W]

I've recently taken delivery of a 1998 A/S Ravenna and find that with the Grey Water tank half or even less than half full the movement of the van in transit sends water back into the Shower tray, even lifting the plugs. I understand that there is no trap between the tray and the tank. One suggestion is that an air vent in the top of the tank is blocked so causing a build of air pressure as the waste moves around so sending it back up the pipes. Is this the likely cause ? Any other suggestions ?

[Guest Neal]

Yet another design/build problem from "Britain's leading converters"??

[Guest Derek Uzzell]

A blocked tank air-vent seems a logical diagnosis. One way to check (without removing the tank) would be to pour water down the sink until the waste-tank is filled to capacity. At that point it should begin to overflow through the air-vent. No overflowing (and water rising into the shower-tray) means the tank is effectively unvented. UK converters often use CAK-sourced waste tanks and my experience is that these are usually fitted with several small bore (say 3mm) inserts in the tank's upper surface to act as vents/overflows. These will be prone to blockage if the tank is not cleaned regularly or if muck finds its way into the vents from outside. (Continental common practice is to fit the tank with a large bore 'elbow' vent in the top with an overflow hose leading towards the ground.) Waste-water backing up in the way described is certainly not normal for the Ravenna design, nor for any other Auto-Sleepers model for that matter.

[Guest Ray]

Hi Alf, this problem used to occur in our Autosleepet Exec. The drain pipe leaves the base of the shower, winds it's way under the van before going UP and into the top of the waste water tank, its a stupid system as it always leaves the drain pipe full of water which sloshes back up into the shower tray while driving, soaking the shower carpet. There is a very simple solution. Get a plunger or rubber sucker large enough to cover the shower drain. Remove the wooden handle and replace it with a piece of plastic pipe about 10inches long. drill a small hole, about 0.25 Inches through the center of the plunger so that when you put it over the drain and blow, the pipe is immediately cleared, problem solved. We also use this to clear drain pipes from sinks when draining down for the winter. Simple solutions are always the besy.

[Guest Derek Uzzell]

Alf's reply proves just how little I know. With a drain-hose layout like Alf's Executive's it should be possible to prevent the water in the bend of the hose entering the shower-tray. Introducing a T-piece into the drain-hose at its lowest point and adding an open-ended section of hose extending above the level of the water tank's inlet should do the trick. This would give the water retained in the bend the opportunity to move into the extension hose rather than take the route back into the shower. (Perhaps!!) Motorhome builders often have funny ideas about water systems. My new Hobby has a separate shower at the very rear of the vehicle, but the waste-water tank is at the front (just behind the cab) with all the waste-pipes running within the insulated floor. The result is utterly predictable with effective shower-tray draining being impossible if the vehicle is parked at all nose-up. It's a 'feature' of the design and, short of putting a drain-pump into the system, is a nuisance I shall have to live with.

[Guest Alf W]

The A/S Service Centrre has replied as follows - "Having previously experienced this problem the best resolve we have found is to fit a non-return valve in the waste tank feedpipe, having done this, to our knowledge there have been no further problems". Thank you all for your replies. I'm still considering which way to go !

[Guest Bill]

At the risk of provoking Roy Hamilton's wrath, why not just throw out your wate tank, and carry a Wastemaster (like out tugger friends)?

[Guest Alf W]

Further to Ray's contribution - there are 3 drains in the base of the Ravenna shower tray, and in any case the amount of grey water coming back suggests that it i s coming direct from the tank and not from a U-bend in the waste pipe.

[Guest Derek Uzzell]

A non-return valve should offer an effective solution and I notice that CAK market a couple of non-return valves for just this purpose. Presumably (having become aware of the problem) Auto-Sleepers fitted such a valve to subsequent models having similar waste-tank installations?!

[Guest Alf W]

Blocked air vents now proved to be NOT the problem ! Hey Ho !