I'm going to fit a wc below the stairs on the ground floor of our
semi, and attach to the same soil stack as the existing FF wc.
Is there likely to be a problem with syphonage - such that when I
flush the upstairs toilet, the ground floor toilet will gurgle?
should I consider putting some kind of vent bypass pipe from the lower
section of the stack? I vaguely remember learning about this, but have
never seen it done. Perhaps it isn't necessary.
1. Or will it be ok re syphonage?
2. Is a Saniflo macerator a good idea, or is a conventional waste
Provided that your stack pipe is properly installed, I would not expect
a problem with syphonage. (Our ground floor WC is not under the stairs
but does connect to the stack pipe which services the upstairs WC and
bathroom. No problems. Not even a trace of a ripple on the ground floor
WC when the upstairs one is flushed.)
I suggest you look at the archive if this group for general opinion of
Saniflo. (Summary: It will need unblocking. Unblocking is extremely
unpleasant.) I can't imagine a reason for installing one if a
conventional waste is possible.
Hypothyroidism is a seriously debilitating condition with an insidious
same here downstairs loo is more or less directly below a bath shower
and two toilets with no problems what so ever, you can hear the water in
the stack pipe as its internal but you don't get any movement of water
in the downstairs loo
Surely Saniflo is a breach of Trades Descriptions: Sani == Sanitary
and Flo == Flow, both of which seem questionable.
Seriously though, provided your waste instalation complies with
Building Regs in respect to pipe sizes and open vents it will be
fine. In essence make sure it uses 110mm plastic pipe or if it's
older then the cast iron equivalent and that there is an open vent
within (IIRC) 6 instalations away and preferably on the last
installation of a run. In any normal setup these requirements are
already easily met and you'll probably find that your pipe to upstairs
goes on to roof level where it is open vented. In essence this open
venting provides an "easy" path for air to get in so that there is
never a negative pressure to induce siphonage. Even if you have an
automatic valve upstairs instead you'll probably be fine.
The only other thing you might need to look out for is wether other
wastes join the downpipe near your intended join. If so you have some
other requirements to meet to avoid backflow. Not hard usually but
you do need to meet them.
Provided that a) the distance to the stack from your new toilet doesn't
exceed 6m (or less if there are a number of bends), or b) there is a
vent on the existing stack (which there should be anyway for a toilet
above the ground floor), then you shouldn't have a problem. Even if you
do, you could stick a 'Durgo' valve on the new branch.
"If no-one on the internet wants a piece of this,
From memory Hugo I think you couldn't fit a Durgo on the new branch as
to comply with regs these need to be installed above the flood level
of all fittings so it would need to be higher than the upstairs loo.
That's from memory though so the OP might like to check the regs
before dismissing the idea. Mind you I suspect it wouldn't be
neccessary anyway as I, like you, think he's probably compliant
On Sat, 11 Oct 2008 20:32:16 -0700 (PDT) someone who may be
Not if you follow the regulations with regard to distances, falls
and the like. Make sure no other appliances join the pipe close to
the new connection.
Necessary in rare cases, which are extremely unlikely to be
encountered in a house. Even if it was necessary in a particular
installation there is a lot to be said for avoiding it by, for
example, adding another stack. It was done in the distant past when
they had less experience of the then fancy new concept of having
toilets and basins inside buildings. Toilet pans are unlikely to be
affected anyway, it is more likely to be basins.
If gravity drainage can be arranged then it is always better.
Simpler, uses no electricity and less likely to go wrong. However,
that doesn't mean one should pay much attention to the loud voices
of the trolls on the subject. Provided they are properly installed
and used macerators work fine. If they are abused they don't, but
that is true of many things (including gravity drainage).
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
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