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Picture for category Støy fra varmepumper og motorer

Heat pumps fans and generators

Noise from heat pumps, generators, fans, motors and units

Noise from heat pumps, generators, fans, motors and units etc. is low-frequency noise that over time can lead to irritation and neighbor quarrels. This type of low-frequency noise is typically twofold:

  • Airborne noise from the engine that bothers the surroundings. Here we look at shielding / cassette with cladding of noise-reducing cloth such as Acoustiblok.
  • Structural noise from the motor that goes via the contact point into the structure and propagates. Here we look at vibration absorbers under the legs and insulation of the contact points.

How to reduce airborne noise

Acoustiblok is a subsidiary of NASA and uses Nano technology for a number of advanced products, including Acousti block 3 mm, which reduces noise by up to 80% of the noise that would normally pass through. Used in houses (ceilings, floors, walls), around engine rooms, outdoor and indoor generators, heat pumps, units, ventilation systems, etc. Comes in rolls of 137 x 914 cm. Joints should be covered with Acoustitape. For cracks and holes, use Acousticaulk noise-reducing sealant.

Shielding of noise with wooden box

You can make a simple wooden stand as a cassette around the engine, with a suitable opening for air that goes in and out. The inside of the wall is covered with a layer of Rockwool and covered with 3 mm Acousti block. The surfaces should be tight except for air openings.

For taller machines and larger tasks, you can make panels clad with Acoustiblok, or use Acoustifence. By making a framework, a higher fence or a clamped wire, you can hook on Acoustifence, a somewhat more flexible version of Acoustiblok 3 mm. It comes in 183 x 914 cm, weighs 85 kg and has eyelets every 15 cm for hanging.

Dressings as described usually provide significant help. But remember that echoes from walls behind or against, and vibration propagation to the trunk of the building, can give variable results.

The closer you get to the noise source, and the denser you get the tire surface, the lower the noise.

How to reduce structural noise

If the engine is on a foundation that can scatter structural noise, use vibration absorption under the legs and attachments. Heron 10 and 20 mm vibro mats are powerful substrates for vibrating motors. 10 mm is delivered in rolls of 1.05 x 10 m where we can cut the entire running meter. 20 mm is delivered in mats of 104 x 244 cm.

For smaller machines use Sylomer. With its rigid cells and compact shape for many applications in plants and machines, this is often used as an elastic intermediate layer similar to a spring. The elastic polyurethane material deforms under stress and compressive loads, but always returns to its original shape. Thus, it isolates and reduces vibrations that can have negative effects on people, environments and materials. The properties of this suspension can be adapted to the need for the application and of the construction, with the use of several layers for increased thickness and effect.

Sylomers come in 12 mm thick, 40 mm wide and 5 meter long rolls that can be cut up to a base on legs. If the machine is heavy, place a small plate under the leg for weight distribution and use two strips of Sylomer, preferably a double layer if necessary.

Sound trap for heat pump, machines and pumps etc.

If you want to make a sound trap that can be placed around the noise source, the sketch below can serve as a good starting point. All interior surfaces are covered with Lydac-P acoustic foam. Sylomer vibration tape is used under all contact points.

Do you want to know which noise reduction products are best suited for reducing annoying noise? Contact us for a non-binding conversation, or order the products from our website! You can also visit our store in Oslo, we have the coffee ready!

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