Air Heater Banks for duct applications

Complete air heater banks incorporating the choice of elements are designed and built to meet the requirements of individual air conditioning installations. Once we have been provided with full details of the job, the most economic arrangement of elements, banks, etc, will be selected to comply with requirements. Terminal boxes are custom made to suit your duct size. Heaters are wired in number of steps required to a terminal block inside, therefore enabling your electrician to connect up power supply easily.

Job data required for finned or unfinned heater banks

1. Nominate the element to be fitted or standard specified, ie, AS1668 Part 1 or AS3102
2. Size of duct and entry side for bank.
3. Total kilowatts required.
4. Number of control steps needed and whether wiring is single or 3 phase.
5. Details of controls required to be fitted to banks.


Air Heater Banks for package units

Package unit heaters comprise of elements mounted in a steel frame with removable terminal cover for easy connection of power supply by electrician. Job data required as above. (Delete item 2) in lieu of, state size or brand model of air conditioning unit requiring heater.



Finned air heating elements

Element specifications



Heater bank

Controls

A) Adjustable temperature cutouts are also available.



B) Fixed set point over-temperature cutouts. Manual or automatic reset types are available for incorporation in banks, in either surface mounted Klixon or capillary tube versions such as GEC TL4.



Terminal boxes

Standard boxes

Under normal circumstances we select appropriate boxes, elements, etc, to give the most economic combination to give you the best airspace coverage inside the duct. Weather resistant boxes are also available at slightly extra cost for use in external applications.



Air heating elements

Element specifications

Air heating can be divided into two broad classes:

Air heating maintenance

In air conditioned buildings

Comfort during winter months is usually provided by ducted heated air throughout a building from a central air conditioning plant room.

This plant is either a reverse cycle unit (cooling and heating) or a cooling unit only, with electric heaters mounted along the duct or inside the air conditioning unit.

Such heaters are used to

Introduction:

If heating in winter months is provided by electrical duct-mounted heaters, you need to know these points.

Location:

Location of the heater banks can be obtained by referring to the duct design layout, supplied by the installer, which should be kept either by the building maintenance staff or in some cases in the air conditioning plant room.

  1. Generally the heater is installed and wired either single phase or three phase back through the electrical contractor, usually located in the air conditioning switch panel; this is controlled by a sensor or room thermostat located in the area heated by that particular heater bank.
  2. The quantity of heat output - for a given heater capacity - is sometimes regulated in stages or time proportional control. (For all this information above refer to Electrical Wiring Diagram supplied by installer.)
  3. Maintenance of electric duct heaters is generally minimal; however, A WARNING SHOULD BE GIVEN THAT BECAUSE OF HIGH VOLTAGE CURRENT NO ATTEMPT TO CHECK OPERATION OR REMOVE A HEATER BY ANYONE OTHER THAN BY QUALIFIED PERSONNEL IS RECOMMENDED.
  4. If a fall-off of heating in an area is experienced, firstly, the power supply should be checked; if power supply is on line, then call for the maintenance personnel to check the heater bank; a simple check on Amps/Volts/Resistance by an electrician will determine if an element is dead or open-circuited; if not, it is most likely that the fault is in the control circuit.
  5. The elements contained in a duct heater are subject after a time to corrosion from: salt, acid or excessive moistureladen air. It should be considered by maintenance personnel, say, every 3 years, to withdraw the heater from the ductwork for inspection of the element radiation finns. The operation of the safety overtemp. cut/out should be checked, together with the inspection of internal wiring for breakages or looseness of terminal connections. Providing an adequate air supply is maintained across the heating elements, a duct heater should last for many seasons of trouble-free operation. All elements and spares are available from General Elements.

Technical considerations

Technical information contained in this publication is intended only as a guide for equipment selection. Users should note that General Elements are not under any obligation for selections made, this is carried out at the users own responsibility.

Comfort heating

Guide for kilowatts required for room heating based on a 20oC difference between inside and outside temperatures (interpolate for lower differentials).

Plot A: Room with low external exposure, window and door area <15%
Plot B: Insulated room, 2 or 3 external walls, window and door area <30%
Plot C: Uninsulated room, fully exposed but lined inside
Plot D: Temporary structure, fully exposed, uninsulated,
unlined