Rapido kitchen sink slow to drain

[davidmac]

Hi the kitchen sink in my Rapido is slow to drain the water away' The washroom hand basin and the shower drain as fast as the water goes in. I put some drain cleaner down the sink but no improvement. Then took some of the pipework apart and poured about four litres of water directly into the pipe and the water ran away no trouble. When all connected up to the sink again water is slow to drain. Is this caused by the trap below the plug. There is an air vent on the opposite side of the trap to the outflow pipe. Does anyone else with a Rapido have this problem?

Regards David

[Derek Uzzell]

David

 

How slow is slow?

 

The shower-tray on my 2015 Rapido 640F drains OK - water-drainage is not fast, but no slower than I would anticipate given the relative positions of the shower-tray and the waste-water tank. The pudding-basin-shaped wash-basin also drains OK, though drainage-speed is affected somewhat by the ‘stance’ of the motorhome when it is parked. ‘Spinning’ the water in the basin to allow air to enter the trap improves drainage-speed, but this ploy is not really necessary. There is no problem wih drainage from the kitchen sink.

 

I recall noticing in the past that Rapido were fitting ‘air-vent’ pipework to sink/wash-basin traps and I thought that (in principle at least) this seemed like a good idea and should optimise water-drainage.

 

The trap used on my Rapido’s sink and basin is similar to the one in the attached photo and I'm guessing this is the type of trap you also have. My traps have one of their two outlets blanked off, but I believe your motorhome has a vent-pipe on the 2nd outlet.

 

Logically, as you can pour water directly into the sink’s pipework and it runs away rapidly, water OUGHT to drain equally quickly from the sink, particularly as your sink’s trap is vented. Presumably you have confirmed that the trap’s air-vent is not blocked, (and the trap itself has no gunge in it, of course) as failure to let air into the trap when the sink is draining would reduce the drainage-speed.

[davidmac]

Hi Derek, thanks for your response. You asked how slow is slow. Yesterday two inches of water in the sink took an age to drain away, probably 2-3 minutes, today, armed with a watch 2 inches of water 40 seconds drain away, even got a small vortex formed so no problem now. Perhaps there was some muck in the pipe and the residue of the drain cleaner left overnight has cleared it. The trap is the same as the one shown just that the vent is an open pipe with a 90 degree bend up to just below the underside of the worktop.

Thanks

Regards David

[tonyishuk]

Our Rapido also suffered from the "full o cr@p" waste which seemed to be sawdust and bits left from the construction phase.

 

I used a ordinary sink plunger and GENTLY worked it until there was free flow. Our Rapido has solid pipes rather than corrugated hoses, So I guess solvent joints, but I would not want to blow a compression joint.

 

Rgds

[Derek Uzzell]

David’s Rapido is 2007 vintage and purchased in May this year. Any construction-phase rubbish should have been flushed out of the water system by now, but that still leaves seven years for kitchen-sink ‘crud’ to build up in the waste pipes if the previous owner(s) have not bothered to clean them.

 

It might have been worth shoving a garden-hose into the pipework when it was detached from the sink trap and (carefully) running water under mild pressure through the pipework, but now that the problem has gone away it’s probably best to leave well alone. If it reappears the ‘enema’ method might be worth trying.

 

My Rapido also has rigid waste-water pipework, but its route to the waste-water tank is mysterious and, if a leak developed at an inaccessible point, you’d probably need to dismantle half the motorhome’s interior to fix it. As you rightly say, care needs taking not to over-stress the pipework.

 

(As David’s Rapido’s sink-trap is vented by an open pipe, the ‘plunger’ approach won’t (or shouldn’t) work unless the vent-pipe is blocked beforehand.)

[davidmac]

Hi the waste pipe is a rigid pipe with push fit elbows and joints, no o rings just a tight fit. The kitchen is positioned on the left side in the middle of the m/h. The waste pipe goes from the sink through the space where the trauma boiler is under/behind the shower behind the wheel arch then appears under the rear single bed and disappears under the centre steps into the waste tank.A lot of hidden inaccessible twists and turns so I would not put any pressure in the pipe because it could be very tricky to refit any joints that come adrift. All is working well now so I will use drain cleaner at regular intervals .

Regards David

[tonyishuk]

As in most drain blockages use a plunger to suck, rather than push debris was the approach I took. Once the suck allows free ish flow, gently work the plunger too allow push. The seesaw action of both water and waste material should allow the blockage to break up.

 

I take the point that there should be no construction material left in the pipe work of a mhome of some years use, but could be a cause of holding debris such as hair, grease etc, if the thin strips of ply like material that came out of mine.

 

Use of a different types of chemical blockage cleaners might help, until you get some idea of the blockage material, grease, hair, cotton buds, pencil shavings. It is difficult to know until summat comes out at the other end.

 

rgds

 

Ps O/T. If you have roof bars , make sure there is mastic under the clamps and screws. Rapido seemed to be a little light on mastic application, as we found to our cost when water dripped onto the bed.

 

[Derek Uzzell]

tonyishuk - 2017-06-25 8:29 PM

 

As in most drain blockages use a plunger to suck, rather than push debris was the approach I took. Once the suck allows free ish flow, gently work the plunger too allow push. The seesaw action of both water and waste material should allow the blockage to break up...

 

 

Presumably (as with my Rapido 640F) your 7090F’s ‘traps’ are not vented like davidmac’s sink-trap is? As I said earlier, if the trap has the 90-degree-bend vent Rapido has used on some models, a plunger (blowing or sucking) won’t work unless the vent is blocked off.

 

With a kitchen-sink waste, the usual cause of a blockage will be accumulated grease and food particles. Drain cleaner or strong bleach should remove this as long as there is some water-flow through the pipework that will alow the cleaner/bleatch to reach and attack the muck.

[davidmac]

Hi I think there is a basic design fault in the waste water system which cannot be overcome. The waste pipe goes horizontaly to the corner of the cupboard, drops to floor level and then continues flat along the floor around a number of bends and finally into the tank.This pipe run is 6 to 7 feet and with no fall, if the m/h is parked at a wrong angle, drivers corner lowest, the pipe will have standing water in it and any any sediment will sink to the bottom of the pipe eventually blocking the pipe.I think frequent use of drain cleaner is hopefully the best answer.

Regards David

[Derek Uzzell]

My 2005 Hobby T600-FC motorhome had its shower-tray in the right rear corner of the vehicle and its waste-water tank at the FRONT just behind the left cab door, with the shower’s waste pipe running near horizontally through the insulation between the vehicle’s floor and the metal chassis-pan beneath. Inevitably, if the motorhome was parked nose-up, the shower-tray would not drain. How well the wash-basin (also sited towards the back) drained also depended on the motorhome’s attitude when parked, partiIcularly how it was levelled laterally. It was something one learned to live with.

 

After using the drain-cleaner, you could try raising the front of your motorhome well up to produce some fall in the long pipe that runs along the floor (I assume the waste-water tank is at the back), filling the sink with water and letting it drain away. This should aid removal of any debris/muck in the pipe that the drain-cleaner has attacked.

[stevec176]

I've had similar problems with my Rapido 665f and I've worked out it depends on how level the van is, not just fore and aft but side to side too. Maybe it's the way the pipes are routed but eventually it always drains away, just have to be patient.

 

[mikebeaches]

When our Rapido V68 van conversion was brand new the kitchen sink was reluctant to empty completely.

 

Close inspection, on pulling out the drawer underneath, showed the waste pipe from the sink going UPHILL!

 

I couldn't fathom a simple fix, so took it to the supplying dealer (Highbridge) and they cut about an inch-and-a-half off the downpipe, so there was a gently fall from the sink - has been fine since then. B-)