Air-Cooled chillers are a very common HVAC piece of equipment and are installed and operated in most commercial and industrial buildings. The chillers supply cold water and cool air to the buildings they service. The chillers operate by drawing air via large fans over copper coils filled with refrigerant that is transported by compressors. Air cooled chillers generate noise and if located in a sound sensitive location will need to be treated with some noise control measures. The main noise source is the compressors. The compressors emit a whine at a frequency that is particularly bothersome to the human ear. The second noise source is the Condenser fans. The fans generate a low frequency drone that will carry for some distance. Other sources of noise are the compressor piping, oil separators and the sheet metal housing.
eNoise Control can help you reach your chiller noise reduction goals with the many sound control products that can be applied to your chiller application. We recommend assessing your chiller noise control project and estimating the level of sound reduction you will need to reach your goal. Most chiller manufacturers can provide sound power data on their units and we can use this acoustical data to predict what the sound level will be a distance from the chiller. If the client needs to meet a local noise ordinance or code, we can assist in designing a sound control system to meet the projects objectives. We employ CadnA environmental predictive software to assist our clients in assessing the current sound levels and what different levels of noise control solutions will provide to obtain their acoustical goals.
Noise Control Solutions
The solution options are outlined in the following table and each solution is explained in more detail on the construction, installation and performance.
|eNoise Sound Control
|Economy Sound Blanket
|3 – 4 dBA
|Removable acoustic blankets for compressors only. Stainless steel wire / 2.5” Velcro vinyl flaps Double sewn construction
|Enhanced Sound Blanket
|4 – 8 dBA
|Better Sound Reduction
|Removable acoustic blankets for compressors, piping, and oil separators. Higher sound reduction
|6 – 20 dBA
|Fan Noise Above Unit
|Acoustical Silencers designed for the units airflow and pressure loss requirements. Primarily noise above the unit.
|Sound Curtain Barrier
|10 – 12 dBA
|Blocks Line of Sight
|Exterior grade curtains straight wall or multiple sides covered. Easily attaches to chain link fence.
|Steel Sound Barrier
|10 – 14 dBA
|Modular Steel Sound Barrier Wall with absorptive panels supported by structural steel columns
|Full Sound Enclosure
|15 – 30 dBA
|Highest Noise Reduction
|Full Sound Enclosure with absorptive panels and intake and exhaust silencers designed for units airflow and pressure loss.
Economy Sound Blankets
This noise control option is an easy to install and remove compressor sound blanket that provides sound reduction of the compressors only. It is an easy add on to the specifications of supply and typically reduces the noise levels by 3-4 dBA which takes the edge off the annoying tonal wine of the compressors. The sound blankets are constructed from materials suitable for being outdoor for 10+ years and a good choice for many chiller applications.
Enhanced Sound Blankets
This noise reduction option builds on the compressor sound blanket by adding coverage of additional noise generating items on the chiller – compressor intake and discharge piping, oil separator and/or economizer. This added coverage provides sound reduction up to 4-8 dBA overall. Constructed of the sound blanket outdoor rated material for may years of service.
Chiller or condensing fan silencers are a good option for unit noise control if the subjects to receive the noise are located above the unit. Multi story office buildings and apartments with units located on adjacent roof or on grade can be affected by the fan discharge noise as well as the compressor sound exiting the top of the unit. The fan silencers are engineered with very low pressure loss and designed to accommodate the published CFM of the subject fans, silencers provide high sound reduction performance to areas above the unit. Constructed of galvanized solid and perforated steel and acoustical grade fiberglass. The silencers are typically supported with a structural steel frame because their weight which the units casing is not designed to support.
Sound Curtain Barrier
Outdoor Sound Curtain Sound Barrier provide an easy to install and low cost solution as a sound barrier wall. The sound blankets can be attached to new or existing chain link or stockage fencing. The sound curtains offer an acoustical absorber and sound barrier in an rugged outdoor rated engineered material. This is a very popular solution for schools and businesses with an existing chiller security fence. The blankets can be attached with nylon wire ties, tie wire or mechanical fastener through the provided grommets located across the tip and bottom of each blanket.
Steel Sound Barrier
This is very popular solution for new construction of schools and hospitals as well as business with rooftop units. The sound barrier walls are constructed of I-beam structural steel columns with baseplates designed and sized for the local wind load and modular steel panels constructed of 16 gage solid outer skin and 22 gage perforated inner skin filled with acoustical grade sound absorber. This construction offers longevity and durability as well as superior noise control of your chiller unit.
Full Sound Enclosure
This solution offers the highest level of noise reduction. A full sound enclosure with four sides and a roof around the chiller with silenced intake and exhaust silencers to allow the required airflow for the operation of the unit. Constructed of a structural steel frame and modular steel panels constructed of 16 gage solid outer skin and 22 gage perforated inner skin filled with acoustical grade sound absorber. This enclosure contains all the chiller compressor and fan noise while acoustical silencers allow for the quiet exchange of large volumes of air to allow the chiller to function at its optimum levels.