I have a concealed loo cistern behind a panel, which has developed a
leak at the exit, which is clearly the result of the exit pipe being
shoved up against the AAV on top of the soil stack, and the joint being
severely strained. So I want to reposition the cistern a bit. Ideally,
it would go forward and a bit lower than before, in order to be able to
gain access to the cistern from above (it's completely blocked by a
large purlin at the mo. Don't ask - he wasn't a great plumber.)

Question - at the moment the bottom of the cistern is about 30 cm above
the rim of the bowl, which is fed by an L-shaped pipe 1.75"?) from the
cistern. If I lower the cistern so that the drop is only, say 10cm
above the bown, would this mess up the flush? I can't decide logically
whether the answer is "yes of course", or "no the length of the drop is
irrelevant".!

Thanks all
David

Lobster wrote:

Question - at the moment the bottom of the cistern is about 30 cm above
the rim of the bowl, which is fed by an L-shaped pipe 1.75"?) from the
cistern. If I lower the cistern so that the drop is only, say 10cm
above the bown, would this mess up the flush? I can't decide logically
whether the answer is "yes of course", or "no the length of the drop is
irrelevant".!

No. 2, - irrelevant, within reason.
The L shaped pipes come in a size of around 60cm x 30cm, and are
supplied to be cut to size.
Alignment is key to a good fit - as you know. I've found it is the
cistern joint that leaks before any other - the rubber connector to the
pan seems a lot better than the little rubber o ring on the cistern
joint.
Alan.

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To reply by e-mail, change the ' + ' to 'plus'.

In an earlier contribution to this discussion,
Lobster wrote:

I have a concealed loo cistern behind a panel, which has developed a
leak at the exit, which is clearly the result of the exit pipe being
shoved up against the AAV on top of the soil stack, and the joint
being severely strained. So I want to reposition the cistern a bit.
Ideally, it would go forward and a bit lower than before, in order to
be able to gain access to the cistern from above (it's completely
blocked by a large purlin at the mo. Don't ask - he wasn't a great
plumber.)
Question - at the moment the bottom of the cistern is about 30 cm
above the rim of the bowl, which is fed by an L-shaped pipe 1.75"?)
from the cistern. If I lower the cistern so that the drop is only,
say 10cm above the bown, would this mess up the flush? I can't
decide logically whether the answer is "yes of course", or "no the
length of the drop is irrelevant".!

Thanks all
David

Bearing in mind that close-coupled cisterns sit directly on top of the bowl,
I would think it would be ok - even though the water from close-coupled
cisterns has a more direct path than yours.
--
Cheers,
Roger
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The message
from Lobster contains these words:

I have a concealed loo cistern behind a panel, which has developed a
leak at the exit, which is clearly the result of the exit pipe being
shoved up against the AAV on top of the soil stack, and the joint being
severely strained. So I want to reposition the cistern a bit. Ideally,
it would go forward and a bit lower than before, in order to be able to
gain access to the cistern from above (it's completely blocked by a
large purlin at the mo. Don't ask - he wasn't a great plumber.)

Question - at the moment the bottom of the cistern is about 30 cm above
the rim of the bowl, which is fed by an L-shaped pipe 1.75"?) from the
cistern. If I lower the cistern so that the drop is only, say 10cm
above the bown, would this mess up the flush? I can't decide logically
whether the answer is "yes of course", or "no the length of the drop is
irrelevant".!

It probably makes some difference but probably not enough to matter. The
higher the cistern the more potential energy the water starts off with
but set against that the longer the pipe the more resistance to flow. I
must admit it is a long time since I have seen one but I don't think the
old high level cisterns that used to be commonplace were conspicuously
better flushers and close coupled cisterns of course sit right on the
bowl and mostly work ok with less water per flush than was the norm.

--
Roger Chapman

A.Lee wrote:
Lobster wrote:

Question - at the moment the bottom of the cistern is about 30 cm above
the rim of the bowl, which is fed by an L-shaped pipe 1.75"?) from the
cistern. If I lower the cistern so that the drop is only, say 10cm
above the bown, would this mess up the flush? I can't decide logically
whether the answer is "yes of course", or "no the length of the drop is
irrelevant".!

No. 2, - irrelevant, within reason.
The L shaped pipes come in a size of around 60cm x 30cm, and are
supplied to be cut to size.
Alignment is key to a good fit - as you know. I've found it is the
cistern joint that leaks before any other - the rubber connector to the
pan seems a lot better than the little rubber o ring on the cistern
joint.
Alan.


I changed the height and the horizontal distance on mine recently, both
by about 75mm, and it all works fine.

On 2 Jan, 21:36, Roger wrote:
The message
from Lobster contains these words:

I have a concealed loo cistern behind a panel, which has developed a
leak at the exit, which is clearly the result of the exit pipe being
shoved up against the AAV on top of the soil stack, and the joint being
severely strained. So I want to reposition the cistern a bit. Ideally,
it would go forward and a bit lower than before, in order to be able to
gain access to the cistern from above (it's completely blocked by a
large purlin at the mo. Don't ask - he wasn't a great plumber.)
Question - at the moment the bottom of the cistern is about 30 cm above
the rim of the bowl, which is fed by an L-shaped pipe 1.75"?) from the
cistern. If I lower the cistern so that the drop is only, say 10cm
above the bown, would this mess up the flush? I can't decide logically
whether the answer is "yes of course", or "no the length of the drop is
irrelevant".!

It probably makes some difference but probably not enough to matter. The
higher the cistern the more potential energy the water starts off with
but set against that the longer the pipe the more resistance to flow. I
must admit it is a long time since I have seen one but I don't think the
old high level cisterns that used to be commonplace were conspicuously
better flushers and close coupled cisterns of course sit right on the
bowl and mostly work ok with less water per flush than was the norm.

Ya reckon ? The outside loo I removed when demolishing, could have
flushed a cat down, such was the ferocity (and noise) of the flush. I
should imagine the cat would add to the noise also. Of course the
enormous amount of water helped too. The water head was around 1.5
metres.
Simon.

Stuart Noble wrote:
A.Lee wrote:
Lobster wrote:

Question - at the moment the bottom of the cistern is about 30 cm above
the rim of the bowl, which is fed by an L-shaped pipe 1.75"?) from the
cistern. If I lower the cistern so that the drop is only, say 10cm
above the bown, would this mess up the flush? I can't decide logically
whether the answer is "yes of course", or "no the length of the drop is
irrelevant".!

No. 2, - irrelevant, within reason. The L shaped pipes come in a size
of around 60cm x 30cm, and are
supplied to be cut to size.
Alignment is key to a good fit - as you know. I've found it is the
cistern joint that leaks before any other - the rubber connector to the
pan seems a lot better than the little rubber o ring on the cistern
joint.
Alan.


I changed the height and the horizontal distance on mine recently, both
by about 75mm, and it all works fine.

Thanks all, I'll get me hacksaw out then. And if the lowering does have
an adverse effect, I'll just have to feed more all-bran to SWMBO.

David

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