suite waste pipe

[Zehroni]

Dear All,
My master bedroom en suite waste pipe come out of the siphon flow (see image 1) runs under the mater bedroom floor board to the second bedroom (see image 2 the grey pipe) then outside the wall to connect to the house main swear 4 inch pipe which is at the back of 3 beds typical mid traced house. This pipe gets very often blocked and the pressure build up resulting in splitting one of the solvent welded joins, either a coupling union or a 90 degree bend. I was lucky first couple of times that the split was under the floor broad of the en suite which was easy to get access to and repaire. This time the leak in the middle of the sitting room ceiling which is under the master bedroom. To get to it, I have to take all the furniture out, strip the laminating flooring then the floor board which is hard work and I do not think it would solve the problem permanently.
My plan re run the pipe a long the inner walls of the sitting and the dining room to the kitchen, through the house back external wall to the main swear pipe.

My question are:-
1. Does it have to be 22 mm all the way? Or can I connect to either 32mm or 40mm as soon the 22mm comes out of the downstairs landing ceiling . I understand the reason for connecting the siphon flow to 22mm pipe is to maintain the pressure. Obviously, 22mm is cheaper and easy to lay and hide.
2. If I have to run 22mm all the way, is there flexi solvent welded pipe that I can use as one piece all the way to the outside of the house which easy to bend without taking much space or broke.

 

[muggles]

Looks very badly fitted, there should be no 90º bends on the run anywhere as they block up, it should be a pair of 45º bends with as much distance between them as is practical. The joints shouldn't push apart though, if they are doing then they either haven't been glued or the wrong type of pipe has been used.

There should also be a constant fall on the run, the angle of which will be determined by the manufacturers instructions of your macerator. These will also contain information about the size of pipe, number of bends, and length of run that can be used with that particular unit. If you don't have them they should be available on the Internet.

There's no such thing as flexible overflow pipe that would be suitable for this

 

[Zehroni]

Muggles,
Many thanks for the reply.
What are the disadvantages if I feed the 22 mm pipe to 32mm or 40mm as soon as it leaves the siphon flow with couple of 135 degrees elbows to smooth the 90 degree bend? Will it lose pressure or can the flow continue?. The 32 mm 40 mm will be below the 22mm by approximately a foot or two and will run horizontally y levelled for 10 meters before it drops ( 2.5 metres) at the back of the house to be connected to the main waste pipe. The reason I prefer the 32 or 40 pipe (if I can use) is the are wider, easy to unblock and can afford to fit 90 degrees elbows.