Air handling units (AHUs) are common in the mechanical rooms of large buildings. These mechanical rooms are designed with small footprints to maximize tenant space, leaving minimal room for noise control. As a result, the mechanical room, and in turn the air handling unit, is often situated close to the occupied space. Without a proper noise control solution, a noise problem will likely occur. AHUs are available with numerous fan types, orientations and configurations, all of which have different flow distribution requirements and static capabilities. Selecting a silencer that ensures the fan is operating the way it was designed s a challenge.The type, shape and size of the silencer does not only depend on the required insertion loss. Silencers with flow shaping internals help minimize pressure drop and provide uniform air distribution for fan intake and discharge.EX casing silencers are designed with the acoustic media out of the airstream, resulting in noise reduction at no added pressure drop (compared to ductwork).

Projects: Baystate Medical Center, Metropolitan Life Office Building, IBM Celestica Noise can break-out of duct walls and into the occupied space. This usually occurs at the point of entry into a room.Even if the silencer is located right at the noise source, noise from other equipment in the mechanical room can break in to the ductwork after the silencer and result in a noise problem. An acoustical analysis is required to determine how much breakout will occur and where the noise is likely to break out of the ductwork.HTL (High Transmission Loss) silencers and sometimes HTL ductwork is recommended in mechanical rooms where break-in is possible. Installing a silencer at the wall between the mechanical room and the occupied space will reduce break-in before and prevent breakout noise from reaching the occupied space.Projects: Charles Tupper Office Building, CBC Headquarters, Fredonia Opera House Noise traveling through the ductwork and out of the diffusers and return grills is a problem that should be addressed at the design stage.

However, where to locate the silencers, obscure duct transitions and precise calculation of the amount of silencing required are common issues that designers run into. This process always needs to start with a systems analysis that includes transmission loss calculations, aerodynamic analysis and a survey of the project-specific requirements (space, IAQ, pressure drop, and cost). A project-specific solution can then be selected and applied.Projects: Metro Center, Lietrim Computer Center, CBC Headquarters 2 AHUs usually require intake and discharge silencing solutions, however cramped layouts often don’t allow the room for them. In addition to space restrictions, shorter duct runs pose the problem of increased System Effects and potentially generated noise. Fit-the-system silencers, which take the shape of the duct, enable designers to achieve the insertion loss required across all bands in the limited duct space available, while also keeping system effects to a minimum.

ASHRAE recommends 3-5 duct diameters on either side of a silencer, however this amount of space is rarely available. Fit-the-system silencers help overcome space restrictions that most consultants face on a regular basis.Projects: Baystate Medical Center, Waterpark Office Building, IBM Celestica, Niagara Courthouse TheaterAt full 100% throughput, AirMaster heat recovery ventilation units emit only 35 dB(A) at 1m. Where noise limitation is crucial, a further reduction can be obtained by setting air flow to 80% of full throughput, resulting in only 30 dB(A) at 1m.2 ton air conditioner dimensionsEC (electronic commutation) drive motors enable the air handling unit fans to modulate between 40% and 100% of full throughput. ac unit is leaking waterThis means that air delivery is always closely aligned to room requirements, so that the power consumption profile is consistently as low as possible. my ac unit won't turn off

It is not necessary to have defined speed settings, such as trickle or boost.AirMaster heat recovery ventilation units placed against the walls of a room to be served have negligible air pressure loss. Units can also be used away from walls, with ducting of up to around 10m length. In these cases, the fan drive motor is delivered with a higher setting, so that the fan can overcome duct pressure loss and still manage the required air volume. Although noise emission for these units is higher, the duct muffling effect largely neutralises this increase and holds emitted noise to the same duct-free 30 and 35 dB(A) levels.AirMaster air handling units with only 30 dB(A) noise emission are a godsend to designers tasked with finding ventilation solutions for projects such as Special Educational Needs (SEN) schools, clinics and community centres with quiet areas.Even with the bypass damper fully open, AirMaster heat recovery ventilation units are able to reduce noise by approximately 49 dB. When placed next to classroom windows exposed to traffic noise around 60 dB(A), the muffling effect of direct ventilation units reduces the resultant noise ingress to 7 dB(A).

This is so low as to be negligible.AirMaster air handling units can provide a constant supply of fresh air without the noise ingress and pollution which result from open windows. Natural ventilation, such as opening windows, can be inexpensive to begin with. However, it is hugely energy inefficient , can cause draughts, is uncomfortable in winter and impractical on days with high winds or rain.Where the level of environmental noise is known (typically from a field survey), SAV Systems can provide a spreadsheet to establish the net impact of such noise after passing through an AirMaster unit. This would be relevant for situations such as classrooms subject to traffic noise.Having installed an AirMaster air handling unit for its low noise characteristic, any site operator can rest assured that equipment noise will not increase during its operating lifetime. With maximum throughput, it does what it says on the tin: 35 dB(A) @ 1m.For further information, please forward your request to:We look forward to hearing from you!