fred wrote in message ...
In article , Flat
Eric writes
Thanks very much for all your comments Fred, they were useful. I have
a few more questions in response
You're welcome, but I am winging it here, I have no experience of saniflo at
all, hence my initial reluctance to respond.

A sounding board for ideas is a good thing atleast. May be prompt
someone else to post to the thread, so we all pool knowledge/common
sense - what this is all about eh?

you don't really want a right angle bend in the pipe
just before joining the stack
Why is that? I understand that bends in general should be swept bends
and not right angle, but what's the significance of proximity to the
stack exactly?
My thoughts were that if it is going to block then it will do so at the 90deg
bend and had also assumed that you would be taking it straight through
the wall just before you bent it into the stack. That would make for a join
near impossible to dismantle and assess for blockage. Best to make
potential problem areas accessible for service.

Fair enough. May be fitting an equal tee with an acces plug for
rodding between boss onto soil pipe and swept bend through wall would
be advisable. Avoiding 90 deg bends and allowing access

Also, why copper, it's not the normal way to do things so as
a result there won't be fittings to do the job. Suggest you do it in
waste pipe of the appropriate size and
I understand that using 22mm copper is the best way of plumbing
Saniflow waste (as it is more robust than solvent-weld plastic). I
don't think it's that uncommon, therefore I assumed that someone may
have come across the same problem
- joining 22mm copper to cast iron stack
Again not my area, but 22mm does seem very small,

I have to agree on this, but think this reason is one of robustness.
Need to do some more probing here eg talking to my local Saniflow
stockist etc. It is for a toilet pump.

Since using copper for Saniflow waste does appear to be recommended
[from Saniflow website "All pipework should be either copper or CPVC
conforming to BS7291. Do not use flexible or push-fit pipework. " ],
there must be a recomended methdo of connection to the stack...?
Anyone???

Also, I would have thought that plastic would have a
smoother interface at the joints, less risk of burrs/blockage

d'you reckon? IMHO, not sure there'd be much in it myself...

aaaaand serviceability again, a few non solvent joints in the plastic would
let you dismantle if required.

Personally dont like the idea of having any push-fit joins for a
Saniflow - certainly not inside the house anyway. May be a good
argument for solvent plastic is than you *can* fit occasional equal
tee and access plugs along the route to allow for rodding as I have
commented above. I suppose you could do the same with a compression
fitting/speedfit stop end on copper

to make a copper to (40mm plastic) waste pipe joint
Are there fittings to join 22mm copper to say 40mm plastic waste?
You can get rubber reducers from 40mm to 21.5mm plastic (20mm
overflow pipe) that may suit, but I certainly wouldn't trust such a joint to
any kind of pressure.

Quite! 10 bar I think the motor runs at!

Perhaps if it was the joint at the stack then it would
be ok, so that would be boss, solvent adaptor to 40mm then 40/21.5
rubber reducer but def don't make it concealed anywhere

Could insert such an adapter fitting after the swept solvent bend,
down to copper, with the copper running at 45 deg though the wall and
just emerging to make the adapter ie potentially dodgy connection
*outside*. [There must be a better way of doing this....?]

Again, hope that helps . . . . some

Yes thanks very much - has got me thinking at the very least!