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APPLICATIONS VAV COOLING & HEATING VAV COOLING & TERMINAL REHEAT ADVANTAGES Individual control Reversing change-over option Easy installation No commisioning Accurate control No regular maintenance

The RICKARD VARIABLE GEOMETRY THERMO-DISC Ceiling Diffuser is a thermally powered VAV diffuser which contains its own temperature sensing and volume control mechanism. In appearance and construction the Thermo-Disc is similar to the popular electronically controlled vari-disc diffuser but has the advantage that it requires no external wiring or power supply. The Thermo-Disc is available in two basic options. The 5 series is a cooling only VAV diffuser while the 4.02 series will provide full VAV temperature control in both cooling and heating modes. The change-over between control modes is automatic and is carried out by means of a unique patented change-over mechanism.

Supply air is discharged horizontally in a uniform 360 degree radial pattern while the Variable Geometry feature ensures that adequate room air movement is maintained throughout the full range of volume variation. All diffusers are manufactured from electro-galvanised sheet steel and are finished in a chip-resistant baked epoxy powder coating which is available in a wide range of colours.

2 OPERATION

GENERAL DESCRIPTION

Room temperature is controlled by varying the supply air volume in accordance with demand. No other system is more energy efficient, since the volume of air is controlled to match exactly the requirements of the space served by the unit, no more or less. Volume control is achieved by moving a disc, known as the control disc, vertically up and down in the diffuser so as to vary the aperture through which air passes. This results in the “Variable Geometry” concept which effectively maintains constant air movement in the room throughout the range of control, from 100% down to approximately 30%. The position of the control disc is varied by means of a wax filled thermal element which responds to changes in sensed temperature. The wax contained in the thermal element melts at the formulated temperatures to expand or contract. With a rise in sensed temperature the expanding wax extends the plunger, causing the amplifying lever-arm mechanism to move the control disc such that the supply air volume is changed to the extent that is required to maintain constant room temperature. When the wax cools down the plunger retracts under the action of the return spring, causing the control disc to move in the opposite direction to counter the change in sensed temperature. The room temperature sensing element is located inside an air induction channel above the appearance panel trim-plate. Adjustment of the room temperature setpoint is achieved by rotating the blue adjustment knob. To access this knob, unscrew the support pins, unhook the hook from the support post so the trim disc & thermal actuator can be removed from the diffuser. The adjustment knob has calibrated markings and the setpoint may be adjusted to suit individual requirements. It is advisable that no changes are made to the factory setpoint of (22deg.C) 72deg.F until the space is occupied. This will give realistic operating conditions, after which individual units may be adjusted to suit individual requirements.

HEATING/COOLING THERMO-DISC

The Series 4.02 heating/cooling Thermo-Disc is identical in appearance and performance to the cooling only version, the only difference being the addition of a change-over pill which automatically changes the action of the diffuser when in the heating mode. This allows full VAV control of room temperature when warm air is supplied to the diffuser. When the supply air temperature exceeds (22deg.C) 72deg.F the changeover is initiated and at (26deg.C )79deg.F the change-over to heating mode is completed. Now the diffuser will open as sensed room temperature decreases, and vice verse. Change-over back to cooling mode is completed when supply air temperature drops to (19deg.C) 66deg.F. For best results the supply air temperature should be maintained above or below the change-over temperature range although operation within this range is feasible. For a full description of VAV systems go to Section 1 of this catalogue.

3 DIMENSIONS AND MOUNTING METHODS

The basic THERMO-DISC ceiling diffuser concept supports a wide range of diffusion unit styles. The basic diffuser usually drops into a square opening between ceiling tees or can be circular in plastered ceilings.

4 ADVANTAGES OF THE THERMO-DISC

Personalized comfort

The Thermo-Disc controls its own VAV zone, with each diffuser adjusting between (20deg.-24deg.C.) 66deg.F - 77deg.F. The Thermo-Disc will sense and control the temperature within (1.5deg.C) 3deg.F of set temperature. (Factory setting (22deg.C) 72deg.F). There is no need for thermostats, which are often situated incorrectly i.e. in incorrect room. This is because it is situated in the diffuser itself.

Capital & operating cost savings

The Thermo-Disc is a self powered system, which requires no other power source i.e. electrical or pneumatic. There are numerous savings on cabling/piping, thermostats and other electrical/mechanical equipment.

Low maintenance

The Thermo-Disc is reliable and requires no routine preventative maintenance. The absence of electrical or pneumatic equipment and accessories also means less maintenance and fewer potential problems. All moving components are easily accessible from below the ceiling. The entire control mechanism can be removed from below in seconds. The only items ever likely to need attention are the thermal elements and these can be easily replaced.

Flexibility

The Thermo-Disc can be easily relocated, there is no need to move electrical cables/pneumatic tubes or other related equipment. If additional units are required, their addition does not disrupt the rest of the air handling system.

5: TEN YEAR WARRANTY

Rickard warrants that its Thermo-Disc diffusers, exclusive of any options or accessories (whether factory or field installed) shall be free from defects in material or workmanship for a period of ten (10) years from the date of shipment and agrees to repair or replace, at its option, any parts that fail during said period due to any such defects which would not have occurred had reasonable care been taken,provided that such parts have been inspected by Rickard and found defective and provided the diffusers have been given normal and proper usage and all parts and controls remain unaltered. Rickard makes no warranty of merchantability of products or of their fitness for any purpose or any other express or implied warranty which extends beyond the limited warranty above. Rickard’s liability for any and all losses and damages resulting from defects shall in no event exceed the cost of repair or replacement of parts found defective upon examination by Rickard. In no event shall Rickard be liable for incidental, indirect or consequential damages or damages or injury to persons or property. Rickard shall not be responsible for freight to or from its premises in connection with the inspection, repair or replacement or parts under the terms of this limited warranty nor for the cost of removal or installation. Rickard Air Diffusion Pty. Ltd. reserves the right to change specifications and data without prior notice.

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