sink trap question

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 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?

Thanks very much for this it all makes sense now

Regards

Tony

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 :)

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.

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.

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

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.

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