What is the connector called to attach this p-trap to an equal tee?

[vertexape]

Hello,

I am plumbing in a double basin sink based on the first pic that I mined from a Reddit thread. (happy to accept suggestions on if this is correct as well)

My waste pipe is 32mm and mounted in the floor. I will be mostly solvent welding

However when I look at the top of the p-trap, I have no idea what the name of the connector needed to attach the top of the p-trap with a section of pipe that will go into the tee.

I thought it might be a 32mm straight coupler, but it doesn't fit the top of the trap. I can only think it needs to be something like a threaded attachment to 32mm solvent pipe?

I've googled about every possible guess I can think of!

 

[fowlerboi]

The bit you're trying to attach something to fits to the basin. You then come out the horizontal section with a bit of 32mm pipe. Do the same for the other side and then using some fittings get them to meet into the tee ensuring that the swept tee faces the right way.

You've chosen an anti vac trap for your double basins which is a smart choice but 80% of the time they don't fit the basin. You may need to get an adjustable anti vac p trap instead

 

[vertexape]

The bit you're trying to attach something to fits to the basin. You then come out the horizontal section with a bit of 32mm pipe. Do the same for the other side and then using some fittings get them to meet into the tee ensuring that the swept tee faces the right way.

You've chosen an anti vac trap for your double basins which is a smart choice but 80% of the time they don't fit the basin. You may need to get an adjustable anti vac p trap instead

View attachment 86546

hello @fowlerboi - thanks very much for your reply. Yes this makes sense, I'll explain how I thought I'd got around it, along with my drawing of what I "thought" was correct.

I had specced a mcalpine s29 female coupling that fits the sink waste into the tee. I was going to go to try to setup the drawing attached. The section from the trap to the downpipe wouldn't be this long in reality, it's just to show it without the diagram overlapping. Do you think a double trap is the way to go?

There was a fair amount of people on the Reddit thread saying a dual p-trap was a bad idea, hence why I thought the setup in the first picture was preferable. Perhaps there was no AAV in their setups. I'd have to find it to check.

Admittedly on my p-trap, there's a small AAV, so perhaps I don't need the one off the floor waste connection pipe? I was thinking about both basins draining and trying to prevent any pressure issues. Maybe that's overkill, but I was following that first setup I posted as my waste is in the floor.

For the H&C feed, I was going to put an isolation valve with a section up to a tee with a tap tail on each so it can feed the mixer on each sink.

Thanks in advance for any advice.

 

[fowlerboi]

what you're after to go on the top of the trap is a polypipe ws47w

Choice is yours on how you do it but you're looking at reddit which is mostly used by Americans who are advising you on American plumbing practices. We don't worry so much about venting and inspection hatches for basin wastes, although it wont hurt to put them in

 

[vertexape]

what you're after to go on the top of the trap is a polypipe ws47w

Choice is yours on how you do it but you're looking at reddit which is mostly used by Americans who are advising you on American plumbing practices. We don't worry so much about venting and inspection hatches for basin wastes, although it wont hurt to put them in

cheers @fowlerboi, absolute legend

 

[Ben-gee]

If you are talking about a kitchen sink?

The traps and waste pipes should be (1 1/2”) 40mm not 32mm.

If at all possible I like to put a p trap on each bowl, so two p traps in this case, and then join the pipes together later.

 

[vertexape]

what you're after to go on the top of the trap is a polypipe ws47w

Choice is yours on how you do it but you're looking at reddit which is mostly used by Americans who are advising you on American plumbing practices. We don't worry so much about venting and inspection hatches for basin wastes, although it wont hurt to put them in

cheers @fowlerboi, absolute legend

cheers @fowlerboi, absolute legend

Screwfix do a mcalpine-s31u-compression-bsp-connections-straight-connector-white-32mm-x-32mm

Is this one the same connection on the trap end, but with a compression rather than solvent weld (just looking for something I can use this weekend) find the sizings really confusing.

 

[vertexape]

If you are talking about a kitchen sink?

The traps and waste pipes should be (1 1/2”) 40mm not 32mm.

If at all possible I like to put a p trap on each bowl, so two p traps in this case, and then join the pipes together later.

Hello @Ben-gee - thanks for your reply. No it's not a kitchen sink, it's a double basin for our ensuite. So the waste is 32mm in the floor.

I found a few examples of 40mm double bowl kitchen sink plumbing as that's quite common, so I was basing my idea of of this complete setup that you can buy for that (obviously without the appliance spigot) but with 32mm pipe. Despite looking you don't seem to be able to purchase as a kit like this for 32mm / 1 1/4

 

[fowlerboi]

yes it will fit. Screwfix have the wrong product codes on their website though make sure you don't end up with the 40mm version

 

[vertexape]

yes it will fit. Screwfix have the wrong product codes on their website though make sure you don't end up with the 40mm version

thanks @fowlerboi , will do!

 

[Ben-gee]

Hello @Ben-gee - thanks for your reply. No it's not a kitchen sink, it's a double basin for our ensuite. So the waste is 32mm in the floor.

Ah ok thanks for clearing that up (you mentioned basin and sink in first post, I know most people use them interchangeably but to plumbers they are specific and different!)

I would still put individual p-traps on each basin and then tee them together. Would add in an air admittance valve to stop gurgling of the other basin if necessary and there was room.

 

[vertexape]

Ah ok thanks for clearing that up (you mentioned basin and sink in first post, I know most people use them interchangeably but to plumbers they are specific and different!)

I would still put individual p-traps on each basin and then tee them together. Would add in an air admittance valve to stop gurgling of the other basin if necessary and there was room.

Ha Ha @Ben-gee , I guess saying a "basin sink" is really unhelpful terminology

Thanks for clarifying the double trap setup.

So yes, I was using an image of a double sink waste kit, and trying to apply this to a double basin. Where the sink waste kit I posted is concerned, is the single trap they use in this down to a cost aspect (i.e. making it cheaper), rather than a choice or what works best?

My other question is if I added a second trap and then teed them together, where does the AAV get placed in the setup? as I assume the base of the tee would naturally go straight down to the waste pipe in the floor? I know the trap I have has a small air valve but I have a dedicated one I may as well use now!)

many thanks everyone for the advice so far.

 

[Ben-gee]

I think the rationale behind the kits is to save space in the cupboard. But the long horizontal section can lead to smells if deposits are left in it, and I personally think if the two p traps point backwards it can actually leave more usable space in the cupboard. I have this set up at home on my kitchen sink and it never blocks or gurgles (why on earth did I say that, it’ll probably explode now!)

 

[vertexape]

I think the rationale behind the kits is to save space in the cupboard. But the long horizontal section can lead to smells if deposits are left in it, and I personally think if the two p traps point backwards it can actually leave more usable space in the cupboard. I have this set up at home on my kitchen sink and it never blocks or gurgles (why on earth did I say that, it’ll probably explode now!)

heh heh. Ok thanks for explaining @Ben-gee. I have modified a cupboard to be the vanity unit under the basin (which is 800 wide) so there should easily be space for a dual trap.

 

[vertexape]

I've ended up with this drawing based on @fowlerboi and @Ben-gee 's advice.

I added some 135 Deg elbows at the base as the waste is right next to the feeds, and I want to shift it across a bit to clear some space around the tap tails.

my only concern is the traps not reaching the basin wastes as I read the AAV needs to be 4" from the main waste pipe? I might have to extend the down pipes with the adaptor that @fowlerboi recommended.

 

[Ben-gee]

Attach the traps directly to the basin wastes.

 

[vertexape]

Attach the traps directly to the basin wastes.

roger that! given I want to add an AAV and my waste joining at the floor, how should the trap outlets be spaced when connecting to the down pipe? or can I go straight to each side of a tee and then down?

 

[Ben-gee]

You can’t go to each side of the tee as one will be against the sweep.

Either use two tees, like your drawing, or use a single cross tee (has four connections) - if you use this then the aav can come off the top of it.

 

[vertexape]

You can’t go to each side of the tee as one will be against the sweep.

Either use two tees, like your drawing, or use a single cross tee (has four connections) - if you use this then the aav can come off the top of it.

Thanks @Ben-gee, learning so much through this! appreciate your input.

 

[vertexape]

Thanks @Ben-gee, learning so much through this! appreciate your input.

annoyingly I can't see anywhere that stocks a cross tee in 32mm, only 40mm and 50mm.

Is it okay to use a reducer on all inputs on the cross tee?

 

[vertexape]

So here's my scenario now - if I attach the traps to the basin wastes, you can see that I won't have space for the AAV valve. This is the max the telescopic p-trap will extend to on the right.

Is it acceptable to extend a piece of pipe straight down from the wastes and mount the traps lower (I'd imagine taking them to level or slightly lower than the shelf in the middle, so I can have the AAV valve mounted at least 200mm above them.

Or should I angle the outfeeds from the traps with 135 degree bends downwards? this doesn't seem like a good idea.

Any advice? thanks.

 

[vertexape]

hey @fowlerboi @Ben-gee this is how it turned out. Would have liked the AAV to have more height but I didn't want to drop the traps any more than I had already, and I couldn't source a 32mm cross tee (they only seem to be 40mm and 50mm). I did have 2 traps the same but thought it couldn't hurt to put the one with the small air valve on it as well

Don't know how legit it all is, but it doesn't leak and the sinks drain faster than any other sink in our house!

Thanks for your advice