Latest revision as of 03:29, 31 July 2020

There are 3 different types of pipework noise:

waterhammer (foghorn like noise or hammering sound)
hiss
expansion noises (occasional clunks)

Each has different causes and different solutions.

Waterhammer

Waterhammer is resonance of the water column inside the pipe. This can happen at low frequency, causing a hammering sound, or at auidible frequency, making foghorn-like noise. It can be very loud!

Solutions

The usual cause is a rubber disc in a tap or fill valve oscillating. The solution is to renew the rubber washer/diaphragm.

Turning down the flow rate also usually works. Usually this gives an acceptable flow rate, sometimes not.

Installing damping on the pipework can also often work, but the forces involved in waterhammer are high and the damping needs to be a lot more effective than just lagging. One sometimes effective approach is to jam a block of damping material between the pipe and wall in roughly the half way point between 2 pipe clips. Do this in a few locations. The material can be expanded polystyrene, solid rubber or folded cardboard, and needs to be inserted fairly firmly to be effective.

Other options

Where the above don't work or can't practically be done, there are other ways to reduce the factors that cause the problems. But none of these have a large effect, so don't always work. Most work by introducing greater damping to the pipework.

Wrap the pipe with lagging.

Box the pipes in. This provides a physical barrier to sound transmission, and creates a void that can be filled with rockwool or similar for damping and sound absorption. The heavier and stiffer the boxing, the more effective it is. Minimise and fill any gaps for best performance.

Lag the noisy pipe wherever it goes outside of where it is causing the noise problem. Eg lagging added in the loft will have some benefit on downstairs noise too.

For pipe under floorboards, place a few layers of carpet offcuts onto the pipe and put the boards back. Carpet damps pipe movement. The carpet should be wide enough to droop down onto the ceiling either side of the pipe. Not recommended for incoming cold pipes due to possible condensation.

Place a weight on the pipe on every other section of pipe run (ie between pipe clips 1&2, 3&4 etc). This changes the resonant frequency of different pipe sections, reducing overall Q.

A flexible pipe section sometimes cures water hammer.

Water hammer arrestors can be added to plumbing at the source of the problem.

Air pockets can help absorb vibration. These are added by using a tee instead of an elbow, and capping the upward pointing new section of pipe. The upright fills with air or dissolved gases from the water, acting like an electrical capacitor.

Hiss

Hiss is caused by very fast water flow rate in a pipe, or by high speed water escape. Hiss is prevented by using larger bore pipe or turning down flow rate.

Other ways to treat hiss include:

lagging pipes
using plastic rather than metal pipe
using larger bore pipe
using swept corners instead of sharp corners
fixing pipe clips to rigid surfaces rather than plasterboard, which acts like a sounding board.
fitting a valve in the affected circuit, or each circuit during initial installation
boxing pipes in, filling the box void with heavy insulating material
if pipe must be clipped to a stud wall, implement noise reducing damping measures in the wall itself.

Clunking

Occasional clunks and bangs are caused by copper pipe expanding and contracting when heated and cooled. When the pipe's rigidly fixed, due to its inherent springiness it builds up force until it slips in its fixings, creating a clunk. It's mainly an issue for kids who get scared, and situations requiring complete silence such as recording studios.

Prevention

Loosen pipe clips slightly where possible
- or replace with clips that can be loosened
Plastic plumbing doesn't suffer this issue

Sound reduction

Fix pipes to rigid walls, not plasterboard
Box & insulate pipes
lag pipes
use plastic pipe

Gurgling Sinks

Air being sucked into the waste pie through the sink trap causes gurgling. One option is to fit an antisyphon trap, which has a second extra tube next to the main outlet. As you can see its simple to convert a standard bottle trap to an antisyphon type. Waterless traps are another option.

Caution

Be cautious about using expanding foam as a damping material, some types expand with huge force after they've solidified and can cause considerable damage.

@@ Line 1: / Line 1: @@
-'''Noisy Pipes''' can be quietened by several methods, most of which are of a similar nature. The amount of effect of each measure will vary, and for best results it is often desirable to combine a few measures.
+There are 3 different types of '''pipework noise''':
+* waterhammer (foghorn like noise or hammering sound)
+* hiss
+* expansion noises (occasional clunks)
+Each has different causes and different solutions.
-==Causes of Noisy Pipes==
-* Water turbulence due to high flow rate & sharp corners
-* Transmission of sound along pipe from a noisy valve
-* Waterhammer - sounds like rapid hammering
-* Lightweight walls acting as sounding board
-* Knocking - Pipe moving against restraints due to thermal expansion
-* Rubber disc in valve oscillating - causes waterhammer or a foghorn-like noise
-* Hiss caused by poor fill valve design
-* Lightweight panels with pipes clipped to them can act as sounding boards.
+=Waterhammer=
+Waterhammer is resonance of the water column inside the pipe. This can happen at low frequency, causing a hammering sound, or at auidible frequency, making foghorn-like noise. It can be very loud!
 ==Solutions==
-===General Solutions===
+The usual cause is a rubber disc in a tap or fill valve oscillating. The solution is to renew the rubber washer/diaphragm.
-Wrap the pipe with lagging.
-Box the pipes in. This provides a physical barrier to sound transmission, and creates a void that can be filled with rockwool or similar for damping and sound absorption. The heavier and stiffer the boxing, the more effective it is. Minimise and seal any gaps for best performance.
+Turning down the flow rate also usually works. Usually this gives an acceptable flow rate, sometimes not.
-Lag the noisy pipe wherever it goes outside of where it is causing the noise problem. Eg lagging added in the loft will have some benefit on downstairs noise too.
+Installing [[:Category:Noise|damping]] on the pipework can also often work, but the forces involved in waterhammer are high and the damping needs to be a lot more effective than just lagging. One sometimes effective approach is to jam a block of damping material between the pipe and wall in roughly the half way point between 2 pipe clips. Do this in a few locations. The material can be expanded polystyrene, solid rubber or folded cardboard, and needs to be inserted fairly firmly to be effective.
-===Where there is already a physical barrier over the pipes===
+==Other options==
+Where the above don't work or can't practically be done, there are other ways to reduce the factors that cause the problems. But none of these have a large effect, so don't always work. Most work by introducing greater damping to the pipework.
-Draughtproof the barrier to eliminate air paths. To see how much difference this makes, open a double glazed window by a couple of mm.
+Wrap the pipe with [[Insulation|lagging]].
-If blocking all gaps is not a practical option, add strips of wood to make any sound travelling through gaps turn round corners. The more corners it has to turn, the more effective this is.
+Box the pipes in. This provides a physical barrier to sound transmission, and creates a void that can be filled with [[insulation|rockwool]] or similar for damping and [[Noise|sound absorption]]. The heavier and stiffer the boxing, the more effective it is. Minimise and [[fill]] any gaps for best performance.
-Add damping to the barrier. Eg fix on a rubber mat, carpet, 2 layers of cardboard or roofing felt, or other deadening material.
+Lag the noisy pipe wherever it goes outside of where it is causing the [[noise]] problem. Eg lagging added in the loft will have some benefit on downstairs noise too.
-Replace the barrier with something heavier & stiffer.
+For pipe under floorboards, place a few layers of [[carpet]] offcuts onto the pipe and put the boards back. Carpet damps pipe movement. The carpet should be wide enough to droop down onto the ceiling either side of the pipe. Not recommended for incoming cold pipes due to possible condensation.
-Add a sound absorbent layer to the barrier, eg rockwool batts. This is not the same thing as a damping layer, rockwool gives both airborne sound absorption and some damping.
+Place a weight on the pipe on every other section of pipe run (ie between pipe clips 1&2, 3&4 etc). This changes the resonant frequency of different pipe sections, reducing overall Q.
-For existing boxing, it is possible to apply a 2nd layer of boxing with a sound absorbent between the 2 layers. Its not often this is necessary, but it might be desirable for internal soil stacks when total silence is wanted.
+A flexible pipe section sometimes cures water hammer.
+Water hammer arrestors can be added to [[plumbing]] at the source of the problem.
-===Specific Solutions===
+Air pockets can help absorb vibration. These are added by using a tee instead of an elbow, and capping the upward pointing new section of pipe. The upright fills with air or dissolved gases from the water, acting like an [[electrical]] capacitor.
-With waterhammer or foghorn noise, replace the rubber diaphragm in the valve or tap at the end of the pipe. This frequently cures it.
-For knocking, replace metal pipe clips with plastic U shape clips. These open fronted clips grip the pipe less firmly, allowing it to move more easily, reducing or eliminating knocking. The other type of U clip, which is open at the rear and has 2 fixing points, allows slight lateral movement, which may be sufficient.
+=Hiss=
+Hiss is caused by very fast water flow rate in a pipe, or by high speed water escape. Hiss is prevented by using larger bore pipe or turning down flow rate.
-In some cases you can happily turn down the water flow rate with a valve, and this can have a big effect on some types of noise. If necessary, fit a valve to do this. This is well suited to toilet cisterns, where slightly slower fill is not normally a problem. This can often be enough stop waterhammer and foghorn effects, and much reduce hissing during filling.
+Other ways to treat hiss include:
+* [[Insulation|lagging]] pipes
+* using plastic rather than metal pipe
+* using larger bore pipe
+* using swept corners instead of sharp corners
+* fixing pipe clips to rigid surfaces rather than [[Partition Wall|plasterboard]], which acts like a sounding board.
+* fitting a valve in the affected circuit, or each circuit during initial installation
+* boxing pipes in, filling the box void with heavy insulating material
+* if pipe must be clipped to a [[Partition Wall|stud wall]], implement noise reducing damping measures in the wall itself.
-Plastic pipe has some acoustic damping effect, uses less sharp bends, and does not transmit noise as much as copper.
+=Clunking=
+Occasional clunks and bangs are caused by copper pipe expanding and contracting when heated and cooled. When the pipe's rigidly fixed, due to its inherent springiness it builds up force until it slips in its fixings, creating a clunk. It's mainly an issue for kids who get scared, and situations requiring complete silence such as recording studios.
-For pipe under floorboards, a cheaper option to lagging is to place carpet offcuts onto the pipe and put the boards back. Carpet damps the pipes & acts as a barrier to sound transmission. The carpet should be wide enough to droop down onto the ceiling either side of the pipe.
+Prevention
+* Loosen pipe clips slightly where possible
+** or replace with clips that can be loosened
+* Plastic plumbing doesn't suffer this issue
+Sound reduction
+* Fix pipes to rigid walls, not plasterboard
+* Box & [[Insulation|insulate]] pipes
+* lag pipes
+* use plastic pipe
-===If the pipe is clipped to a lightweight wall===
-Add damping to the wall, eg rockwool fill. Fire retardant rubber mat also works.
-Replace thin sheet materials on the wall with thicker materials with better sound absorption.
+=Gurgling Sinks=
+[[image:Antisyphon trap 2245-2.jpg|thumb]]
-Remove any clips attached to plasterboard alone, and reclip to where there are studs behind the PB. This is not normally a problem, but amplifies noise if it is.
+Air being sucked into the waste pie through the sink trap causes gurgling. One option is to fit an antisyphon trap, which has a second extra tube next to the main outlet. As you can see its simple to convert a standard bottle trap to an antisyphon type. Waterless traps are another option.
-Where pipe goes through holes in wood, sleeve the pipe with something flexible to stop direct sound transmission from pipe to wall structure.
+=Caution=
+Be cautious about using expanding foam as a damping material, some types expand with huge force after they've solidified and can cause considerable damage.
-Fit a 2nd layer of plasterboard to the wall, staggering the joints.
+=See Also=
+[[Special:Allpages|Wiki Contents]]
+[[Special:Categories|Wiki Subject Categories]]
-===Untested===
-Slightly loosen metal clips to allow pipes to move very slightly, reducing knocking noises.
-==Prevention==
-Use plastic clips rather than metal.
-Fit isolation valves, which assist maintenance and are also an easy means to reduce noise if it occurs
-Choose plastic pipe over metal
-Metal pipes that are barely big enough are noisier than bigger pipes with some flow margin.
-Lag pipes.
-Where not lagged, add occasional mechanical damping pieces to pipes, such as polystyrene blocks wedged under the pipe.
-Avoid clipping pipes to lightweight walls when other routes exist.
-When constructing a lightweight wall, 2 layers of plasterboard with staggered joint positions gives much better acoustic performance than a single layer. It is also more robust and gives longer fire protection.
-Stud walls perform better acoustically if they're made from at least 2x4 studwork. Small sizes eg 1.5" x 2.5" tend to perform poorly in this respect.
-If constructing a low cost lightweight wall without rockwoool fill or simliar, placing a concrete block on each horizontal noggin is a way to improve wall mass and reduce the sounding board effect to some extent. Placing a small piece of a damping material on top of this block will give the plasterboard panels some damping.
-==Materials==
-Materials sold specifically for soundproofing have a habit of being overpriced. In many cases its much cheaper to use standard diy materials.
-Rockwool is a general purpose sound absorber.
-layers of cardboard glued in place, or 1 layer of triplewall cardboard, is effective damping for sheet materials. 2 layers of roofing felt is more suitable where dampness may be encountered.
-Be a bit cautious about using expanding foam as a damping material. It is effective damping, but expands with force and can cause damage.
-==See Also==
 [[Category:Plumbing]]
 [[Category:Noise]]
+[[Category:Fault Finding]]
+[[Category:Heating]]

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Latest revision as of 03:29, 31 July 2020

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