Fairford sink drain

2023 Fairford …new and first trip. Sink will not drain … just dribbles out. Plunging it works but same problem every time. Only fresh water down it. Yes the van is parked Level! Suggestions?

Many thanks for suggestion. 
Apologies for discourtesy!
A belated hello therefor . I guess a typical recent retiree profile for us as new to this. I was an airline pilot and am looking forward to never travelling on an aeroplane again! The whole industry travel process has become positively zoological with the intrusive packing and processing of passengers like beans on a conveyor. I am looking forward to going to places of our choosing in our own time. My most favourite place ( and I’ve been to most) is the South of France..

Stick your finger in the plughole and spin clockwise. Sink drains like a champ!
Also, check out the Fairford FB group. I put a video of this on there some time ago.
Enjoy... Nice van!

Thanks Roj.I’ll try that as the dealer replumbing has not made a blind bit of difference . A bit of a “ nul point” for Autosleeper on this a brand spanking new van……

Did I read somewhere that if you remove the trap it improves? Had ours 7 years and learned to put up with it as it met my expectations that it wouldn’t drain like a sink at home. Swirling works as does a really full sink of water.

I am going to try removing the trap… 
Having looked at it , it seems to me that the combination of a long narrow bore pipe which goes up and down and then up to the tank is just inviting air locks . I’m also thinking about putting a tap on the bottom of the pipe where it emerges under the van …. So that when appropriate… can just let the waste go straight out without wandering across the van and up to the tank.

This is the best solution I've seen (OK it was on a Warwick but you may have room to do similar)....

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That looks interesting.. thanks

That blue component in the picture must allow air to enter the system to overcome the negative pressure in the waste pipe that’s created when emptying the sink (the cause of slow draining). It looks like the cover piece from a fresh water drain tap, which has possibly had a small hole put in it. Unfortunately the picture doesn’t show that.

I’d thought about fitting a conventional air admittance valve, but now realise that because AS don’t fit a trap to the waste, there’s no need to fit a valve designed to prevent smells escaping. They do anyway, if you don’t keep the tank reasonably clean. 

It simply needs an opening that’s high enough in the system, which I presume is what the picture shows.

Tim

I'm still a bit mystified why some A-S kitchen sinks seem to be slow to drain. In our previous van a Duetto and in our current a Kemerton XL I've concluded that mostly it's caused by food debris build-up in the corrugated waste pipe. I'm not sure where the negative pressure can form that others have referred to. Waste water going into the tank will need to displace some air now under positive pressure which should be venting out the top of the waste tank. Did A-S not create a big enough vent on the top of some waste tanks they fitted, did this vent eventually get blocked by food when the waste tank overflowed?

My current thoughts of the cause of the slow empting is a combination of there being a horizontal section of waste pipe before it enters the tank which coupled with the turbulent flow caused by the corrugated pipe leads to the slow flow and poor empting. Any food debris in the pipe wont help, any whirlpool effect from a well directed finger will. As the waste tank fills there's a certain hydrostatic pressure that the latest waste water meets which opposes its inflow.

I don't want to go down the route that Gyne took to gain access to area below his kitchen sink in his Kemerton XL but my guess is that if I did replace the waste pipe with a smooth bored pipe made of silicone our sink would drain much more freely. A-S wouldn't have done this, fitting silicone pipes is more expensive, it's a minor irritation overcome with an educated finger or handy sink plunger, or as often in our sink, have enough water in the bowl and during the empting phase use the sink plug in and out to create sufficient turbulent flow to wash through any debris in the pipe to pass onwards into the waste tank, until next time.

The slow drain is a universal problem but I can be sure it's nothing to do with food waste as none has ever gone down to any of our vans tanks. We always wash up in a bowl and the waste water goes out of the van in the bowl to a drain appropriate to the particular site.