Blocked Discharge pipe

[ChrisR]

I've got a 28mm copper pipe from an unvented cylinder, going into a stack pipe. It's blocked, pretty hard, down at the stack end. Water goes through very very slowly.
There's no access anywhere near the stack end, and there's an elbow or two, so "rodding" isn't possible. Upstream of the elbow there's about 5 metres of straightish horizontal pipe, which a spring goes right down.

SO how would a plumber connect a 28mm copper pipe to a stack pipe, which is probably plastic?
(I'm afraid I can guess...)
Is it possible that "material" from above has dropped onto the copper pipe if it protrudes into the plastic, and blocked it?
At the moment the pipe is full with a bottle full of Mr Muscle trap clearer. It's based on sodium hydroxide. Doesn't attack copper pipe or solder, does it?

I've tried pressurising the pipe with a big drain plunger, nothing doing. Next could be mains water, or air, or maybe a Pango.

ANy bright ideas?

This problem was originally (mis)described here...

 

[Bahco]

Only a thought...........Can you not renew the lot and put a new connection in the stack. A 32 mm adapter in a soil boss might be worth a shot if you can insert the pipe in a bit further.

 

[John506]

Cut the pipe near the blockage

Unblock

Connect the pipe together again by means of a straight connection

 

[gas4you]

I can only guess how the 28mm is connected to the stack pipe.

Perhaps iit is just inserted in an hole and silicone sealed to seal it, or perhaps a strap on boss used and aagin silicone used as a seal?

Anyway guess are not going to solve your dilemma.

I had a similar problem last week with a blocked condensate drain off a boiler that I had fitted about 4 years ago. The condensate was direct into the stack pipe via an R16 and a strap on boss in this case, but unfortunately a new kitchen had been fitted since my install and everything covered with expensive units

Luckily I managed to clear it with my compressor, running at approx 7-8 Bar. Dont know if this helps, have you access to a good air compressor Chris?