Hi

We've had our bath relocated, which means that we have a longer run of
pipe where the outlet comes out of the wall, making its way about six
feet, and an angle of 45degrees, to discharge into the hopper at the
top of the drainpipe.

All tested ok when fitted by the plumber, but when he tested it was
only a case of running the taps in the bath, and on that basis it's
fine. Problem is, when a bath full of water discharges, the force of
water coming out of the waste pipe splatters at great force against
the inside of the hopper, spraying water everywhere.

Just wondering why this is happening - is the 45degree angle such that
the water shoots at much faster than if the pipe was at a shallower
angle? Or should the pipe have a right angle turn in it at the end so
that the water exits vertically?

Mr W

Mr W wrote:
Hi

We've had our bath relocated, which means that we have a longer run of
pipe where the outlet comes out of the wall, making its way about six
feet, and an angle of 45degrees, to discharge into the hopper at the
top of the drainpipe.

All tested ok when fitted by the plumber, but when he tested it was
only a case of running the taps in the bath, and on that basis it's
fine. Problem is, when a bath full of water discharges, the force of
water coming out of the waste pipe splatters at great force against
the inside of the hopper, spraying water everywhere.

Just wondering why this is happening - is the 45degree angle such that
the water shoots at much faster than if the pipe was at a shallower
angle? Or should the pipe have a right angle turn in it at the end so
that the water exits vertically?

Probably both. Most bath wastes I see are at a shallower angle. A right
angle bend on the end might help, or it might just cause the hopper to
overflow more evenly.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Mr W wrote:
Hi

We've had our bath relocated, which means that we have a longer run of
pipe where the outlet comes out of the wall, making its way about six
feet, and an angle of 45degrees, to discharge into the hopper at the
top of the drainpipe.

All tested ok when fitted by the plumber, but when he tested it was
only a case of running the taps in the bath, and on that basis it's
fine. Problem is, when a bath full of water discharges, the force of
water coming out of the waste pipe splatters at great force against
the inside of the hopper, spraying water everywhere.

Just wondering why this is happening - is the 45degree angle such that
the water shoots at much faster than if the pipe was at a shallower
angle? Or should the pipe have a right angle turn in it at the end so
that the water exits vertically?

Mr W

The latter should work.

There is some justification for replacing the hopper with a proper junction.

In article ,
Mr W writes:
Hi

We've had our bath relocated, which means that we have a longer run of
pipe where the outlet comes out of the wall, making its way about six
feet, and an angle of 45degrees, to discharge into the hopper at the
top of the drainpipe.

All tested ok when fitted by the plumber, but when he tested it was
only a case of running the taps in the bath, and on that basis it's
fine. Problem is, when a bath full of water discharges, the force of
water coming out of the waste pipe splatters at great force against
the inside of the hopper, spraying water everywhere.

Just wondering why this is happening - is the 45degree angle such that
the water shoots at much faster than if the pipe was at a shallower
angle? Or should the pipe have a right angle turn in it at the end so
that the water exits vertically?

Changing the shape/size/position of the spout could make a big
difference. If the hopper has a 4" exit, I would direct the pipe
end down that. (Could reduce to 32mm for that purpose.)

Changing the bath U-trap for one with an air admitance valve
would help as it would draw air into the pipe, reducing the
mass of water and the power of the jet at the end of the pipe.

Reducing the pipe to 32mm at the bath end might help by
similarly restricting the flow. Doing it at the hopper end
might not help but just produce more of a jet effect (unless
directed down the outflow as mentioned above).

If the bath has a pop-up waste plug, adjust the plug so it
doesn't open so far, again restricting the flow.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 2008-07-15 08:39:27 +0100, (Andrew
Gabriel) said:

Changing the bath U-trap for one with an air admitance valve
would help as it would draw air into the pipe, reducing the
mass of water and the power of the jet at the end of the pipe.


Is that really true for this example though? I had always understood
AAVs to be there to allow air in when the pipe is empty and there's a
negative pressure further away from the appliance - purpose to avoid
trap being sucked out.

In this case, wouldn't the pressure in the pipe be a little above
surrounding atmosphere and therefore AAV wouldn't open?

Still it might work and nothing is lost by having one.


Another solution may be to fit an elbow at the hopper end to redirect
the water inside that, or perhaps change the hopper to a different
shaped one.

In article 487c57d2@qaanaaq,
Andy Hall writes:
On 2008-07-15 08:39:27 +0100, (Andrew
Gabriel) said:

Changing the bath U-trap for one with an air admitance valve
would help as it would draw air into the pipe, reducing the
mass of water and the power of the jet at the end of the pipe.


Is that really true for this example though? I had always understood
AAVs to be there to allow air in when the pipe is empty and there's a
negative pressure further away from the appliance - purpose to avoid
trap being sucked out.

That's correct, and may also be useful here for that reason, but
not the key point I was making in this case.

In this case, wouldn't the pressure in the pipe be a little above
surrounding atmosphere and therefore AAV wouldn't open?

It's going to depend on the pipework, but generally where you've
got a good smooth fall from the trap onwards as the OP seems to,
you are supporting that column of water by a vacuum at that point,
with the u-trap and plug grating being serious flow restrictions
resulting in the negative pressure just at the point where the AAV
is. If you look at an AAV, it generally opens all the time a full
bath or basin is emptying (but even more at the end of course).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 2008-07-15 09:47:16 +0100, (Andrew
Gabriel) said:

In article 487c57d2@qaanaaq,
Andy Hall writes:
On 2008-07-15 08:39:27 +0100, (Andrew
Gabriel) said:

Changing the bath U-trap for one with an air admitance valve
would help as it would draw air into the pipe, reducing the
mass of water and the power of the jet at the end of the pipe.


Is that really true for this example though? I had always understood
AAVs to be there to allow air in when the pipe is empty and there's a
negative pressure further away from the appliance - purpose to avoid
trap being sucked out.

That's correct, and may also be useful here for that reason, but
not the key point I was making in this case.

In this case, wouldn't the pressure in the pipe be a little above
surrounding atmosphere and therefore AAV wouldn't open?

It's going to depend on the pipework, but generally where you've
got a good smooth fall from the trap onwards as the OP seems to,
you are supporting that column of water by a vacuum at that point,
with the u-trap and plug grating being serious flow restrictions
resulting in the negative pressure just at the point where the AAV
is. If you look at an AAV, it generally opens all the time a full
bath or basin is emptying (but even more at the end of course).

Yes, now I think of it that way it seems right. Would it impact the
result at the hopper though? I'm not sure about that.

"Andy Hall" wrote in message news:487c72a3@qaanaaq...
On 2008-07-15 09:47:16 +0100, (Andrew Gabriel)
said:

In article 487c57d2@qaanaaq,
Andy Hall writes:
On 2008-07-15 08:39:27 +0100, (Andrew
Gabriel) said:

Changing the bath U-trap for one with an air admitance valve
would help as it would draw air into the pipe, reducing the
mass of water and the power of the jet at the end of the pipe.


Is that really true for this example though? I had always understood
AAVs to be there to allow air in when the pipe is empty and there's a
negative pressure further away from the appliance - purpose to avoid
trap being sucked out.

That's correct, and may also be useful here for that reason, but
not the key point I was making in this case.

In this case, wouldn't the pressure in the pipe be a little above
surrounding atmosphere and therefore AAV wouldn't open?

It's going to depend on the pipework, but generally where you've
got a good smooth fall from the trap onwards as the OP seems to,
you are supporting that column of water by a vacuum at that point,
with the u-trap and plug grating being serious flow restrictions
resulting in the negative pressure just at the point where the AAV
is. If you look at an AAV, it generally opens all the time a full
bath or basin is emptying (but even more at the end of course).

Yes, now I think of it that way it seems right. Would it impact the
result at the hopper though? I'm not sure about that.



I once fitted a 135 degree elbow at the end of a pipe to prevent this. Got
the water directed better and stopped if bouncing off the far side of the
hopper.

On Mon, 14 Jul 2008 21:47:58 +0100, Mr W
wrote:

Slow the speed at which the bath empties. Best way is to buy a
few of those chrome-coated plastic hair-traps that just drop into
the outlet.

Oh.. they also stop hairs getting into your hopper too!

(We use them all the time).

H.

On Tue, 15 Jul 2008 11:21:37 +0100, "John"
wrote:



I once fitted a 135 degree elbow at the end of a pipe to prevent this. Got
the water directed better and stopped if bouncing off the far side of the
hopper.


I'll have a go at this first, as seems the easiest, and see how it
goes.


Mr W

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Mr W saying
something like:

Or should the pipe have a right angle turn in it at the end so
that the water exits vertically?

Yep, or a 45deg elbow to achieve the same end.
--
Dave
GS850x2 XS650 SE6a

"It's a moron working with power tools.
How much more suspenseful can you get?"
- House