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ARBB65 Black Bulb Controller

ARBB65 Black Bulb Controller

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Air temperature has long been used as a convenient measure of warmth but there ore many cases where it is unsatisfactory and misleading. For example, air temperature as a measure is unsatisfactory where surrounding surfaces are warm or where there is high air velocity.

A person's bodily heat loss and hence his feeling of warmth depends on Air Temperature, Radiant Temperature of Surroundings and Air Velocity.

Only by taking account of all three variables can a true measurement of human comfort be achieved. Various Indices of comfort have been devised in the course of studies on environmental warmth. The Index known as globe temperature is a practical measurable indicator and has been found to correlate well with subjective assessments of warmth.

The AmbiRad Black Bulb Thermostat is based on the principle of the Globe thermometer. For convenience of installation the Globe is in the form of a hemisphere of high thermal conductivity material with a blackened surface.

Encapsulated within the hemisphere is a highly temperature sensitive element. The rear of the hemisphere is well insulated.

Because of its high sensitivity and its ability to respond to radiation, air temperature and air velocity the Ambirad Black Bulb Thermostat is able to constantly adjust the heating system to the instantaneous thermal needs of the building.

By recognising the true heat requirements of the human body - continuous comfort conditions are maintained yet at no time is the building overheated. By ensuring that temperature overshoot or overheating never occurs, substantial energy economies ore achieved.

The "black bulb sensor" is Installed within the heated room or building at a height of 1.5m from the floor. The signal from the sensor is fed back to an electronic control unit via a three core cable which can be up to 200m In length.

The control unit can be located in, for example, a plant room controls cabinet supervisors office etc where it is protected from unauthorised adjustment. The control unit incorporates separate knobs for the selection of day and night temperatures. The operating periods for the day and night temperatures are controlled externally by time-switches or manual switches (not supplied).



Range of adjustment


Calibration Accuracy

1% of scale range


Better than 0.5°C

Power Supply

220/240 ~ 50Hz

Power consumption


Supply voltage variation

+ 10% - 15%

Switching contacts:


Single pole

Maximum voltage

230V ac

Maximum current AC

16A resistive, 8A inductive

Control Knob functions:

1. Day temperature

Left hand knob adjusts the day temperature within the range 0 to +30°C

2. Night temperature

Right hand knob adjusts the night temperature within the range –5 to +30°C (linear scale)

Instructions for fixing sensor unit

1. A position should be selected 1.5m from the floor where the sensor will be free from undue draughts and if possible between 4m and 5m from one of the heaters to be controlled. Avoid placing the sensor where it will be in an area shadowed from radiant heat (behind racking etc.)
2. Remove the cover of the sensor unit by undoing the four screws.
3. Fix the base to the wall with two screws.
4. Connect the sensor using a three core cable of not less than 0.5mm². maximum length of cable is 200m if 0.5mm² is used. Secure wires in the cable gland provided.

Instructions for fixing the control unit

1. Select a position for the control unit where it will be protected from unauthorised interference or adjustment e.g. supervisors office, controls room etc.
2. Remove the front panel by undoing the four screws.
3. Fix the housing to the wall by means of two screws.
4. Connect incoming and outgoing mains connections, time switch connections and sensor connections as shown in the wiring diagram. Secure connections in cable glands provided by others.
5. Re-fix front panel of control unit.

Typical Wiring Schematic

Under no circumstances should mains voltage be connected to terminal 8 or 9.
Note Terminals 1 and 2 are both neutral and are linked internally. Terminals 3 and 4 are both live and are linked internally.

Time switch Must be of 4 terminal type with separate connections for clock motor and contacts. Contacts closed for day temperature, open for reduced (Night) temperature).

If no time switch used, fit manual shorting switch or permanent link between terminals 8 and 9.

ARBB65 Brochure.




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704150 ARBB65 OandM Instruction Manual 0312.pdf

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Last Modified on 07/07/2016.
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