Oh yes, plumbing, so fun. Don’t worry, soundproofing these installations is more fun. Today we will take a closer look at plumbing installations and how we can reduce or “soundproof” the noise coming from these. We will divide this article into a few parts as each installation has some particularities.
There are many sources of plumbing installation noises. In order to fix them, we need to understand why they occur. After we understand the root cause of the noise, we can move ahead and apply some basic fixes some times. Other times, extensive work is required like soundproofing the whole room or adjacent rooms.
There are two types of fixes based on timing: pre-construction and post-construction. If you are a cautious person and you are here just for the pre-construction tips, I have good news. You won’t spend a lot of money to soundproof plumbing installations because you can design the construction well enough from the beginning.
Post-construction soundproofing is usually more expensive as you can’t just move the central heating unit to another room (cheaply). But if you are in the construction phase, you can easily place the central heating unit and water pump in your basement.
What we will cover
In the first part of the article, we will look at heating installations and particularly how we can reduce the noise coming from these sources:
- Central heating units
- Central heating unit pumps
Then, we will move to bathrooms and other plumbing installations and we’ll take a look at:
- plumbing pipe knock (as known as ram noise, knock noise, hammering water noise, or banging noises in pipes)
- soundproofing water taps and valves
- soundproofing water flow noises
- reducing noises produced by hydrophores
- reducing water falling noise in bathrooms and toilets
So, as you can see, we have a lot of ground to cover so pay close attention, but feel free to move to the next section you are interested in. These are very basic ideas and don’t make up for a full tutorial. However, by using this information, some common sense, and basic soundproofing principles described in other posts, you can have good insights on how to soundproof the thing you are interested in.
In order to apply these soundproofing tips, you need to know some things about plumbing installations or have some time to figure them out, but first things first.
Soundproofing Heating Installations
Soundproofing a central heating unit
So, you are here because you want to find out how to soundproof your central heating unit. Reducing the noise produced by central heating units, mainly combustion ones like gas, wood, petrol, etc., is done in most cases by installing noise interference attenuator systems. These can reduce the noise level by 10-20 dB on the most annoying frequencies.
Warning, some tech ahead:
Noise interference attenuator systems consist of two channels of different lengths, L and L/2, which together force the noise to cancel each other.
Reduction of noise in the case of boilers, for example, is done by avoiding direct connections between the boiler and the rest of its installation or other elements. This is done by installing a floating floor in the boiler room.
Apartments
If we talk about apartments, central heating units must be installed as far as possible from rooms (mainly bedrooms). Placing them further from rooms makes the most sense economically speaking. It’s much cheaper to place them far then to soundproof the adjacent rooms. If you can install it far from often used rooms such as living rooms, you are set. Moving them to a further room is also a solution which sometimes can be implemented cheaper than soundproofing the adjacent rooms.
Other ways to soundproof your central heating unit
There are other ways to reduce the noise, although not as effective. The first one is to install the central heating unit on shock absorbers or vibration isolation mounts. These can reduce the vibration that is propagated through the walls. Also, it will prevent some airborne noise if the central unit is vibrating a lot and it’s mounted directly on a rigid wall.
Another way is to build an enclosure around the central heating unit. Building an enclosure around the unit can reduce the airborne noise if it’s sealed properly. Be aware! Central heating units are very dangerous as the risk of fire and explosion is high. Whatever you do, consult with an expert in central heating units. The materials must be fire-resistant/fireproof to avoid a disaster.
Reducing the airborne noise in the central heating unit’s room without the enclosure is quite impossible. An ultimate solution is to buy a similar central heating unit with a lower noise level (less dB). This is not a cheap solution either.
Quick tips
- Place the central unit far away from quiet rooms
- Install arrestors or shock-absorbing mounts
- Build an enclosure for the central heating unit filled with sound-absorbing materials like rock wool or mineral wool
- Install a floating floor
- Install a quieter central heating unit
Soundproofing pipes noise
Using pumps in a normal setting and within the manufacturers’ limits effectively diminishes the hydraulic shocks and eliminate almost all effects of turbulence and cavitation to the maximum amount possible.
Using pumps with l0w RPM (rotations or revolutions per minute) or speeds under 1000 RPM is, although more expensive, a more advantageous solution. That’s because these pumps have a smaller intake hose and lower displacement speed. These two factors combined result in much lower noise under normal circumstances.
The connection between the pipes and pipeline network is made by using rubber sleeves with metal fittings. These should be such designed in order to absorb the water pulsations. Absorbing these pulsations will result in a much lower noise level.
Also, a final tip on pipes noise is to balance rotative parts of the pump perfectly. Otherwise, they will generate a lot of noise.
Moving on to the bathroom and other plumbing installations
Quick Tips
- Use low RPM pumps
- Use the pumps in normal conditions
- Connect it to the pipelines with rubber sleeves with metal fittings
- Check the balance of the rotative parts
Reducing noise in plumbing installations
The knocking noise in pipes
Air Chambers prevents hammer noises in pipes
The “knock shot” or “hammer noise” phenomenon occurs in closed pipes when the fluid is broken or accelerated in a very short time due to the rapid closure of the valves or the shutting down of a circulation pump. This phenomenon is also known as water hammer noise or just banging noise in pipes.
This is manifested by the rapid propagation of overpressures and depressions that cause damage inside the system along with pipes as well as noise.
Because of this, the shock absorber must be located near monocomando batteries, electrodes, spherical valves, etc. to prevent the negative effects that these devices might cause when closed quickly.
How does the knocking phenomenon, also known as water hammer noise occur?
In hydropower installations, the knock noise phenomenon or water hammer noise occurs as a result of the rapid closure of a pipe on the side of equipment such as monocomando batteries, electrodes, ball valves, etc. The quickness of the maneuver induces a disturbance in the water pressure which spreads inside the pipes in the form of overpressure waves.
The disturbance starts from the closed element (eg. tap, valves), climbs upstream, has repercussions on other equipment or pipe elbows of the circuit, and returns downstream, damping progressively. The overpressure will; therefore, add to the existing pressure in the pipelines, causing the following inconveniences:
- pipe breakage
- tanks and flexible connections
- the bonding of joints
- welding joints and sanitary items
- damage to the cutting, retention and adjustment devices
- high noise level and strong vibrations in both the piping and the structure.
Overpressure is influenced by multiple factors that make the phenomenon difficult to replicate in the laboratory:
- the closing time of the equipment
- length, diameter, and tubing material
- water speed
The animation below presents this phenomenon in an easy to understand way:
The solution
Using shock absorbers like rubber mounts is the best way to prevent knock noises.
The use of shock absorbers against water hammer noises is suggested as it can reduce the noise level produced by this phenomenon.
Also, for reducing the noise and vibrations in such cases, satisfactory results can be obtained if you install an air tube assembly into the main pipeline circuit. This is characterized by compressibility and elasticity which can absorb the shocks and noises very well and prevent sending them further into the circuit.
In some cases, you can replace the air tube assembly with a metallic tube closed at one end with a 1 1/2″ (inches or 3.8 cm) and length of about 5.9 feet (or 1.8 meters). This must have taps at both ends in order to drain the water.
Another method to reduce these banging noises in pipes is to connect the pipes using elastic materials.
Quick Tips
- Install an air chamber
- If air chamber is installed, close the main valve, open all the taps, and let them remain open for 1 minute. Then open the main valve again. This operation should clear the air chamber if it’s filled with water.
- Connect the pipes using elastic materials (like rubber mounts)
Reducing the taps noises
Taps can produce very annoying noises. Soundproofing the taps is rather hard if they are not specially designed for silent operation.
Using low noise taps with the appropriate profiles is the way to go. Also, there are special air chamber silencers or water hammer arrestors that can be placed before the alimentation pipe with an air intake.
These are pretty good and assure a laminar flow, but their efficiency is limited due to the residues that fill the air chamber of water silencers.
The usual standard noise in residential buildings, social, or cultural venues is 35dB at a water flow pressure of 2 atm and a 45dB at a water flow pressure of 6 atm. You can find a good pressure conversion calculator here.
Reducing water flow noise in pipes
In order to obtain the lowest possible water flow level for a pipeline network, it is required to size the pipeline network sections to the water flow debit that the section requires in order to obtain a good ratio.
The taps should be sufficiently large to allow free flow of water and again, sized to the required flow (debit) of that specific section of the network.
For example, reducing the flow pressure from 6 atm to 2 atm can reduce the noise level by 10-12 dB. This can be realized by interrupting the pipe continuity with an elastic gasket made of rubber or plastic. Another solution is to use a flexible metallic pipe.
The soundproofing efficiency of elastic insertions grows proportional to the frequency of perturbations. Sound dampening that can be obtained by elastic insertions of 4 – 5.9 inches (or 10-15 cm) length and 2 – 4 inches (or 5-10 cm) diameter placed near the tap can be in the range of 6-11 dB. These apply to high frequencies of about 600 Hz.
At low frequencies, the elastic insertion length can be increased up to 17-18 inches (or 45 cm) which can result in 15 dB of sound dampening.
Reducing the propagation of vibrations through metal pipes is higher on plastic pipes or lead pipes than on copper or steel ones. This is especially true on suspended pipework.
A simple way to reduce the noise caused by vibration propagation through metallic pipes by a range of 10-20 dB is to apply some weights or mass on the pipes.
Pipe dampening device
There are some other solutions that you can use. One of them is to install a sound dampening device such as a pipe filled with sand. It sounds a bit odd, I know. Using this technique, you can reduce the noise level by 4 to 8 dB for each pipe. Look at this figure.
Another way is to just wrap them in an enclosure filled with sound-absorbing materials like mineral wool or rock wool.
These techniques are most effective when applying them to the whole pipework or at least on the terminal pipes (the pipes before and inside the room you want to reduce noise in).
Reflection dampening devices, which are in fact variations of sudden changes of direction in the pipe section, can reduce the noise level by 15-20 dB for a simple one and up to 30 to 40 dB for a double reflection dampening device. Take a closer look at these figures.
Quick Tips
- Adjust the water flow to the needs
- Use elastic gasket insertions made of rubber or plastic to interrupt the pipe continuity
- Use flexible metallic pipes
- Wrap the pipe inside sound dampening devices (inside of a pipe filled with sand or filled with sound-absorbing materials (mineral wool, rock wool))
- Changes in direction of the pipe can reduce the vibration and noise propagation as well
Soundproofing a hydrophore
Hydrophore noises are so annoying, but there are ways to reduce them.
The methods to reduce the noise caused by hydrophore installations are mainly focused on reducing the vibrations (or vibration propagation) of water pumps and their engines. If we can reduce the vibrations caused by the water pump assembly, we can almost make those noises disappear.
If you’ve read one of my last posts, I’ve discussed in detail how you can soundproof your water pump cheaply and efficiently. If you want to check that post, click this link here.
But, if you don’t, here are the basics. The hydrophore is “soundproofed” at the base and sides by dampening layers placed between it and the rest of the building.
You can do this by placing them on a concrete block, placing them into a soundproofing box like I discussed in the water soundproofing article, or install elastic sleeves between the hydrophore and the rest of the installation.
The hydrophore equipment needs to be quiet by itself and placed far away from the rooms in the house. If you can’t place it far from the rooms, or it is already placed and can’t be moved, the news is pretty bad for you, sorry. You will need to use some money out of your pocket, and you may be even forced to soundproof the whole hydrophore room.
So, if you have any means of placing it in the basement, that would be awesome. Making sure that the installation is as far as possible from the quiet rooms is the best soundproofing advice for hydrophores.
Quick Tips
- Place the hydrophore far from quiet rooms
- Place the hydrophore on a concrete box
- Wrap the hydrophore inside an enclosure (a box filled with soundproofing materials: rock wool or mineral wool)
- Use elastic sleeves between the hydrophore and other elements
Soundproofing falling water noise in bathrooms and toilets
This one is even more annoying than hydrophore noises. In order to reduce the noise caused by falling water in bathrooms and toilets, we need to mount elastic connectors between ceramic elements and pipes. We need to soundproof all pipes from the rest of the building and install elastic connectors before taps and valves.
Hotels and Hospitals
When soundproofing hospitals or hotels, you must install silent toilets with a tank that has a valve and a damper. These should be made of plastic materials.
Bathrooms
In bathrooms, you can install elastic rings made of rubber between the drainage gasket and the drain tap. Another way to do this is between the drain tap and soil pipe.
Bathrooms and kitchens should be grouped inside the apartment and placed judiciously inside it. In order to reduce to the maximum the structural noise transmitted to the rest of the rooms, you can install floating floors in these rooms.
The bathtubs and the boiler should be separated from the floor and the side walls with elastic rubber gaskets.
The toilet installation should be installed on elastic gaskets as well and the mounting hooks of the pipe should be insulated from the wall.
All bathroom (and kitchen) taps including shower, bathtub, toilet tank, etc. should be ideally attached to the respective object, not to the wall. This way, we prevent transmitting the noise through vibrations. So, on the sink, install the tap on the sink, not on the wall.
Showers
If we talk about showers, the best way to reduce noise is to use rubber showers. These rubber pipes absorb the noises pretty well and prevent vibration propagation.
In order to soundproof the sink, basins and toilet bowls or tanks, bathtubs, and boilers we need to mount them on shock mounts. These are usually made of rubber. [wiki]
Pipes
You will also need to place elastic gaskets between the mounting point and the building or between the pipe and the hook.
The pipes should be mounted on walls or decks. You can also use dowels insulated with cork from the rest of the building.
The gasket materials you can use are cushion, cork, or rubber. These type of materials can reduce the noise by a factor of 10 to 15 dB.
You need to pay close attention to the construction element to which you attach the pipes. It must not radiate the mechanical energy produced by the attached pipe.
Mounting water pipes and bathroom elements like (above) needs to be done on solid and rigid construction elements. Also, the contact between them and the construction need to be done using a thick elastic rubber mount. For example, between the sink a and the sink bracket or between sink bracket and the wall.
The bathroom pipes should be mounted with a fair number of hooks to massive and rigid elements of the building. These must be mounted at a good distance from the building in order to avoid excessive vibration amplitudes.
Quick Tips
- Use elastic mounts between pipes and other elements
- Use hooks to install the pipes (and keep a fair distance from the wall)
- Do not install tabs, showers, bathtubs, and toilet tanks directly to the wall if possible
Conclusion
Nobody likes annoying plumbing noises. Hearing a neighbor flushing toilet in the middle of the night is not fun. To enjoy this peaceful place named home, we need to “soundproof” these noises as soon as possible.
Remember that in order to effectively reduce the noise, we must apply the measures on all elements of the installation.
