sink trap question

[TMC]

Hi all

next weekend job is to start fitting the new kitchen

question is about sink trap

single sink & connection for dishwasher, hole through wall to outside drain, all in either push fit or compression, simple enough

Looked on toolstation site

some traps are listed as 1 1/2" others as 40mm some say 75 mm seal others

76mm seal

what do the different measurements refer to? ( I know that the 1 1/2" is the tradtional size for sink wastes)

Is the connection to the sink waste the same thread for all wastes?

Are part numbers 52069 and 48286 interchangeable and why is one more than double the price of the other?

Any help appreciated

Tony

[Dave Liquorice]

The1 1/2" or 40mm is the nominal pipe diameter the seal is the depth of water in the trap, not exactly sure where that is measured to/from. Prsumably the highest water level to the highest bit of the trap holding that water.

[The Medway Handyman]

40mm is the token metric for 1.5".

The 76mm bit refers to the water depth inside the trap which forms the seal, so no practical difference between 75 & 76. A shallow bath trap might only have a 40mm seal for example.

Dunno. The dearer one has a brand name?

[TMC]

Thanks very much for this it all makes sense now

Regards

Tony

[Dean Heighington]

As an aside, I would recommend using compression not pushfit. Especially externally as the pushfit tends to perish in outside applications- better still, use solvent weld and decent brand name plastics... Wickes waste for example turns to cardboard in sunny exposures. Also, while you have access and if you have the room, I would recommend putting the dishwasher into it's own upstand and trap and then 'T' into the outgoing waste downstream of the sink trap... It helps prevent gurgling noises and smells over time as things get a bit clogged.

Just my 2 cents :)

[Dave Liquorice]

I don't think any brand waste is UV stabilsed. They all recomend painting in outdoor locations. Some brands may stand up to UV better than others of course.

I'd put in a trap and upstand for every appliance.

[sm_jamieson]

I prefer connecting the appliance in an air tight manner using an appropria= te spigot instead of using an upstand. I formed a U-bend in the applicance = pipe and connected into a spigot and straight into a stub stack under the s= ink. Seems to be working well, and less gubbins behind the machine to preve= nt it pushing back. Simon.

[TMC]

I prefer connecting the appliance in an air tight manner using an appropriate spigot instead of using an upstand. I formed a U-bend in the applicance pipe and connected into a spigot and straight into a stub stack under the sink. Seems to be working well, and less gubbins behind the machine to prevent it pushing back. Simon.

I agree

I fitted mine like this 20+ years ago never had a problem

Regards

Tony

[Dave Liquorice]

Assuming the appliance allows that. Many don't without the fitting of an air admitance valve to prevent back siphoning of dirty water into the machine.

[Dean Heighington]

Exactly. An 'open' upstand is there for a reason. A vacuum in the system can 'pull' a trap.