Air Distribution Grilles, Louvres and Diffusers

VAV Units Variable Air Valves

VAV Unit Model HQ

Our VAV Units – have been designed to regulate the flow of conditioned air in single duct Variable Air Volume or Constant Volume air conditioning systems whilst providing the following design features:-

  • Low Noise Levels.
  • Integral Non Fibrous Attenuation.
  • Suitable For Supply Or Extract Systems.
  • Unique Multi-point Flow Sensor For Easy On Site
  • Commissioning.
  • Low Minimum Inlet Static Pressures.
  • Electronic Or Pneumatic Control.
  • Multi Outlets.
  • Electric Or Water Terminal Reheat

The terminal VAV units – provide air volume control whilst meetings today’s acoustic requirements without the need for additional attenuator sections. The terminal units consist of a low noise, removable, blind type damper, multipoint flow sensor and integral attenuator fitted within a sheet metal housing. The built-in attenuator section is manufactured from non fibrous acoustic material to eliminate the danger of fibre migration. Control components are fitted to an external heavy duty mounting plate and are supplied calibrated and wired prior to shipment. A control panel enclosure is fitted as standard. The unique multipoint flow sensor allows accurate control of the terminal unit air volume in conjunction with either electronic or pneumatic control systems, and easy on site commissioning without loss of control, due to the incorporation of additional flow measurement tappings.

Terminal units are available in 7 different sizes covering the volume range from 0.024 mJ/s to 1.885 mJ/s, suitable for supply or extract applications and inlet static reassures up to 1500 pascals. Hot water or electric heaters can be supplied along with multiple outlet plenum sections. Additional discharge attenuators can be supplied for projects requiring even lower noise levels.

Model HQ VAV Terminal Unit

VAV Terminal Unit


VAV Unit Model HN

The model HN induction air terminals are designed for use in low to medium pressure variable volume, single duct air distribution systems. In addition to regulating the primary air flow as a single duct throttling air terminal the primary air damper operation induces warm ceiling plenum air via the induction ports to provide the excellent air circulation characteristics normally associated with constant volume systems whilst retaining the energy efficiency of a VAV system. The amount of primary air is determined by design air quantity settings (both maximum and minimum). Space thermostats position the primary air dampers to satisfy the space load. On full cooling, the primary air damper is open to provide maximum cool air with the induction of plenum air through the side ports at the minimum. On a decrease in room temperature, the primary air dampers start reducing the cool air flow which increases the air flow through the induction ports raising the total air and thus keeping the air change rate at a much higher level than can be achieved with a straight VAV system In circumstances where heating demands cannot be satisfied with induced plenum air alone optional auxiliary heat may be added by the incorporation of hot water heating coils.

Terminal controls are electrically or pressure independent pneumatically operated. The unique multipoint flow sensor measures primary air flow and compensates for changes in system pressure to keep the flow constant for any given space load. If there is a change in the space load, the stand-alone controller or BMS controller adjusts the 0-10 vdc output signal to reposition the damper actuator to reposition for a different primary air flow. Using the NMV-D2M actuator the maximum and minimum or nominal air flow is factory set since the air flow is “independent” of the inlet pressure. If future air volume adjustment is required our field services engineers can overwrite previous factory calibrated air flows. Our field staff use a notebook computer, interface equipment and digital manometer to reprogram the new data.

The HN range of units are constructed from high quality galvanised sheet steel. Internal surfaces are acoustically and thermally insulated with class ‘O’ acoustic foams of various densities. Available in a range of sizes from 0.070 to 0.800 m3/sec. The unit range is suitable as standard for pressure independent applications in ductwork systems up to 400 Pa static pressure. Units are electronically or pneumatically controlled to a standard range of control sequences, we can also factory fit free issue BMS control equipment. Please contact us for more details.

Model HNEW

Model HNPO

Model HN Terminal Unit Brochure

Model HN Terminal Unit Brochure .PDF