9 replies to this topic

[FLD]

I've refreshed my bathroom and all is great EXCEPT the sink drain runs really slooooowly.  I've put up with it but it's now starting to annoy me.  I have my ideas that it's down to how it's plumbed.  The waste has a trap then the pipe runs down to the floor, then level across to under the bath where it joins the bath waste to go out of the house.  the bath waste runs just fine.  I suspect there's some sort of air lock going on.  Does anyone have any insight into this?  I'm starting to think about sending the sink waste out the wall to fix it.

[g1977]

Is their a sink overflow hole/pipe that also runs into the trap? I have had it where the pipe is a flexible hose that due to it length is curled and retains water. What then happens is the water that is sat there creates an air lock because when the sink empties it draws air down the overflow.

[FLD]

Yeah, there's an overflow which runs into the trap.  I'll have a look at the pipe from that as I can't remember much about that bit. 

[Malcfin]

What type of basin waste do you have, plug, pop up or clicker? If pop up or clicker it may be that it needs adjusted as maybe not opening enough. This is a simple case of taking out the plug and adjusting the screw. Or more likely you could try removing your basin trap and replacing with an anti syphon one, as it does sound as though this could be be issue. Due to you having the drop from the basin to the floor, and the bath waste running okay, it’s unlikely that a small horizontal run would affect this much.

 

Try these two simple fixes first with the waste and trap as this should fix the problem. If unsure on which trap to go for PM me and I can send you a link to best options.

[oblomov]

The age of the bathroom plumbing is relevant.  If the waste goes down to the floor and it's old then it may l be an 'S' trap (rather than a 'P' trap - wall exit)) 'S' indicating the actual shape of the trap.  More modern (plastic) ones that plumb down go straight into a 'bulb' shape.  This has a wall in it and water goes down  in to the bottom of the bulb on one side, and then back up to exit at a right angle where a right angled fitting takes it down to the floor.  Water retained in the 'bulb' prevents backdraught.  Usually thei 'bulb' has a removable screw bottom in order to be able to remove it should detritus build up and cause a blockage, so if you have that set up then think of removing the base of the bulb.  Also usually the sink overflow is integral to the sink and can be seen beneath the back of the sink as a moulded 'lump' which runs down to where the waste fits to the sink.  Modern plastic 'S' traps don't usually have a removable part for cleaning but they're articulated with a joint in the centre of the 'S' which allows them to be situated in more than one plane.  If blocked they are easily released and cleaned by undoing the plastic locking rings.  'S' traps take up space though and are more common under kitchen sinks.  Usually the space behind stem of a supported bathroom sink is limited so these days the bulb type is more prevalent.

 

This link shows various types, the bulb type being the one on the bottom left.

 

https://www.ebay.co....sMAAOSwpwBb2vRc

 

 

Ah.  Conex 301 - those were the days.

Edited by oblomov, 06 February 2021 - 02:39 PM.

[FLD]

Having had some awesome replies (thanks folks) I have the following to report.

the sink plug is a pop up type and if I remove the plug then the sink runs well.  However, I can't see how to adjust it, the plug ins't on many threads!

The trap is an S-trap so this might be a good switch in combination with sorting out the plug.

[Craig S]

Can try a trap that allows air in to the system such as https://www.screwfix...hite-32mm/96792 they are fantastic and stop all the gurgling noises as a bonus.

[FLD]

Thanks.  I'll give it a whirl

[oblomov]

Having had some awesome replies (thanks folks) I have the following to report.

the sink plug is a pop up type and if I remove the plug then the sink runs well.  However, I can't see how to adjust it, the plug ins't on many threads!

The trap is an S-trap so this might be a good switch in combination with sorting out the plug.

There are two types of pop-up, manual with a lever connected to a rod you press on the top of the sink and push to close - push to open.  The manual plugs lift right out and have a rather obvious and locking nut and machine screw on the base which allows adjusting the height of the plug when open.  When I go on holiday it's quite common for me to have to adjust this type in the hotel I'm staying at to get decent drainage flow.  As for the pop-up, I have one upstairs but there is no obvious way to get at the gubbins from above as the plug seems fixed.  From below if you change to a bottle trap and get access you may have more luck.

[FLD]

Perfect, once I get the trap off I'll have a look.  It's one of those push the plug ones.