What is this elbow joint pipe?

Question

This elbow joint is leaking. I think it’s the condensation pipe off the boiler because it seems to leak when the boiler comes on. I’ve tightened it fully but still leaking.

The pipe on the left (white) measures 21.5mm and the grey pipe coming out of the waste pipe seems to measure 29mm

The angle is 90 degrees and it looks like a compression fitting, but i can’t seem to find this elbow joint anywhere

Extra details: This is located under the sink. The boiler is located to the left on the wall. This pipe comes out the bottom of the boiler. The big pipe in the middle going down is the waste pipe

Washer: Looks like a rubber tapered washer. Outside diameter about 28.6. Inside diameter 21.5 height 6.5

Conclusion Actually someone said to check the water isnt leaking from the white elbow joint and running down onto the grey nut.. once I checked it, it was obviously leaking from the white elbow joint, so I ended up sealing up the white elbow

Answer 1

It looks like the downstream end of the elbow fitting is misaligned and under stress, making it hard for the washer to do its job. I've shown it exaggerated at "a" in the picture.

You would fix this by loosening the two compression nuts shown and if possible, if there is one further down the long white pipe, that too.

Align everything as best as possible before retightening. You may need to insert "b" further into the coupling or to cut it half an inch shorter if it's bottomed out. You may need to shorten pipe "c" by cutting out a piece and replacing with a coupler (but first see what can be done further along it outside the photo).

Answer 2

I suspect the elbow is just part of the "elbow plus tap into drain" unit that seems to have been spliced into the drain pipe. Here is a photo of a part with similar function:

(It is called "Drain Waste Trap Pipe Extension Connector 1 1/2" BSP with Dishwasher Input" so if you search for a similar fitting you may find your elbow included as part of a similar whole unit.)

It looks to me like a black compression washer is visible down between the pipe and nut as shown by the arrow below. I would think its inner diameter would match the outer diameter of the gray pipe going into the nut. Similarly, I would expect a compression washer in the other gray nut that fits around the thin white pipe going into it. You should be able to purchase such washers based on your measurements and the assumption that they are standard rubber compression washers.