On 05/07/2012 10:29, The Natural Philosopher wrote:
Nylon was invented about the same time as polyethylene, but AIUI the
latter had properties that made it particularly suitable as an insulator
when centimetric radar started to be used.
Looks a bit like an iron waste pipe to me; don't recognise the collar at
all. What happens outside? One option might be to fit a new plastic pipe
through the wall to an existing iron stack outside (which is what I
have). Then you can have nice modern unbodged pipework inside the house.
Agree it is likely cast iron, I have seen one with a similar collar from
a 60's build, the collar was sealed using lead wool compacted with an
offset compacter/chisel type tool.
I'd cut it off 2" or so from the wall to get a lower entry and use a
flexible pan connector to mate with the inside of the pipe. They're
meant to be self sealing but I'd add sanitary silicone to the
compressible vanes to make sure.
No need to disturb a cast iron stack in good condition, it should last a
century. Hopefully the building is not 99yrs old ;-).
I'm still not sure. Other than a magnet, is there a test?
That's pretty much what I had in mind. How far down the pipe would you
aim to get the flexible connector? Does further = better? I suppose
there's a danger it won't seal properly if it's halfway round a bend
instead of in a straight section.
Probably about 120! But I suspect the first bathroom was installed in
Thanks for the advice.
It wont bend until it is through the wall so you have at least 4"
straight there so nowt to worry about.
You want the pan connector to go into the pipe until it bottoms out or
until all the fins are in which could be 2-4" depending on type.
From your other pics it's def a cast iron stack, that straight vent
section at the top may be something lighter.
Other comments about the pipe being brittle and cracking are valid hence
my suggestion to cut it 2" from the wall so that you can have another go
if it breaks. Maybe start further away then re-cut closer once you have
more confidence also noting that the further from the wall the higher
the pipe will be and that it will need to match your new pan. My choice
could be a 110mm angle grinder with cutting disk, mark your cut line,
score round first a mm or 2 with the grinder then go progressively
deeper until it is cut.
Chose the right distance and you can use a straight pan connector, which
is better than flex. Smart move would be to get a few likely bits in
from a place like BES, they're not expensive and it means you have
exactly the right bit to hand no matter what.
See the bottom of this page:
Distance from the wall will be set by your pan/cistern combo, close
Re comments about breaking into cast iron joints/stacks, just don't go
there unless you have to, there is a high risk of breaking the collar if
you do as it is all so brittle. When you do have to do it, you smash the
ingoing pipe with a hammer, stuff newspaper in the hole to catch the
bits then have to chisel out the stub of the pipe form the socket so not
unsurprising that it often ends in tears.
Thanks for the reply. I've just posted links to another couple of
pictures of the outside -- see my reply to Adam.
Your idea sounds promising, if I can get the old joint apart on the
other side of the wall without damaging it. How did you fit the new
plastic pipe into the old joint?
In my case, I only replaced the vertical "vent" pipe (previous owner had
replaced the angled one carrying fluid). As I recall, once I had removed
all the old iron (a bit fiddly as you don't want to crack the junction)
the new pipe "bottomed" on a step in the collar, which makes it fairly
easy. Pack the bottom part of the joint with something like newspaper,
string, baler twine, rope, etc and create a seal using suitable mastic
or silicone. You can finish off the top with silicone, mastic, or even a
cement filet. Since it never really sees positive pressure (even if
there is stuff flowing down) the seal does not have to be brilliant.
Personally I'd remove right back to the stack, including the tee. You
could put plastic into the existing flange and pack it or buy a plastic
to cast-iron adapter (I'd assume that even if yours is asbestos, it'd
still be a similar size).
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