Reducing Noise Nuisance From an Outdoor Air-conditioning or Heat Pump Unit

Insulating airborne noise (sounds) of an outdoor unit

In order to reduce the noise nuisance caused by an outdoor unit, it needs to be shielded from the surroundings. This can be achieved by means of a partial enclosure, or even better, a complete enclosure. On this page you find advice and products regarding a do-it-yourself version of a complete heat pump enclosure.

Important before you start!

We provide information concerning the acoustic insulation of an outdoor unit. You are supposed to find out yourself to what extent this unit can and is allowed to be shielded by means of an enclosure, this falls outside the scope of our advice. In case you cannot find this information, you can opt for our alternatives: the ACE and DICE heat pump enclosures. Following our advice is at your own risk.

Making an enclosure

As for building a housing, in the ideal case you use the heaviest variant of weather-resistant sheet material, such as concrete plex. Place the unit and the enclosure on an elevation in order to make sure rain or snow stay outside the housing. Make sure that the enclosure or the elevation do not touch the house.

The enclosure should become a solid construction in order to avoid vibration at low frequencies. As for the dimensions of the enclosure, it is important that your outdoor unit has enough free space in- and outside the enclosure. If you want to know the exact amount of free space necessary for your unit, we refer you to its manual. We recommend you to leave a free space of at least 4 inches at the sides and above the unit and of about 12 inches at the front and back of the unit for the supply and exhaust of fresh air. You should leave a free space of at least 20 inches at the front and back at the outside of the enclosure.

The most practical enclosure consists of two equal parts that can be taken apart, which is convenient in case of maintenance. Equip one part of the enclosure with a divider, from which you cut out the shape of the unit. This divider separates the in- and the outflow of air, it divides the enclosure at the inside in a front- and backside. As such, the unit cannot suck up the exhausted air. In the end, recirculating air makes your unit a lot less efficient!

If your unit is closely located to a wall you should make an enclosure that exhausts air at the front and sucks it up at the sides. Create a divider in this case as well, making sure the exhausted air won’t be sucked up again, also referred to as an anti-recirculation divider.

Wooden enclosure that consists of two parts containing black absorption material 

Making sound absorbing blades

The blades of the enclosure, depicted as the angled openings at the front- and backside and provided with black Akotherm sound absorption material, are the most important parts. The blades are made from the same material as the enclosure and should be provided with Akotherm Basic D40 at the bottom. This causes sound to be absorbed before it leaves the enclosure. The sharper the angle and the more blades you place, the more sound is being insulated. Pay attention to the fact that this does mean that less air can be supplied and exhausted! If you happen to be very handy, you can make adjustable blades.

Pay attention to the distance and the thickness of the absorption material as well, we advise to us Akotherm with a thickness of at least 1,6 inches (40 mm). The measurements of the openings between you have to decide yourself. Usually, the supply and exhaust of air should be sufficient if you can still see the unit from outside at a certain angle.

The unit is still visible through the openings of the heat pump enclosure

Additional tips

• Make sure to make the top of the enclosure at an angle as well to prevent water from staying on the surface.
• Install wire netting at the front and back of the blades to prevent birds from building a nest inside.
• Put outdoor units as far as away from neighbours as possible, out of sight, behind a closed fence and equip this fence if necessary with absorption material like Merfopol.
• If you build a partial unit enclosure and the chance exists that the absorption material becomes wet, you should also use Merfopol.

Questions?

If you have questions concerning this topic, feel free to contact us. However, we cannot advise you on matters of air-conditioning or heat pump installations. We also don’t have technical know-how regarding such appliances. If you are searching for a ready-made heat pump enclosure click here: DICE heat pump enclosure.

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