Monitoring the temperature of water within a hot water cylinder provides essential data for managing energy use to save costs. Often this simple information is not recorded accurately.

Usually, a thermostat is strapped around the centre of the tank which triggers the boiler on or off. Operationally, this has worked well for many years. However, accurate measuring provides greater benefits than simply switching immersions on and off, particularly when used with a system such as Irus in hotels or student accommodation.

Energy saving
A complete overview of the tank’s temperature range means that energy use can be controlled more accurately. Maintaining optimum temperatures efficiently will result in huge cost savings.

In a twin element tank, a sensor aligned to each heating element will identify if either of the two elements fail. The maintenance team are sent alerts automatically from the system so they can replace the faulty part – ensuring efficiency and safety.

Finally, and perhaps most importantly, monitoring heating patterns and setting programmes can greatly reduce the risk of Legionella developing in stored water. Monitoring temperatures accurately and collecting the data ensures water safety plans are adhered to and evidential data is logged.

The PRE2000W2-3 kit
The Prefect Irus PRE2000W2-3 is a complete kit of components for connecting a twin element hot water tank system to the Prefect Irus control system.

Control unit
The PRE2000CU3 is the control head unit and the control element of the kit. The head unit collects and stores data from the sensors and controls the power unit and slave relay switching power to the elements.

Power unit
The PRE2000PU3 power unit is the power supply for the low voltage head unit and the slave relay. The power unit houses a 16A relay for switching the 1st element when commanded by the head unit. The power unit utilises mains borne signalling to transmit and receive data and commands between the head unit and Prefect Irus central control. Using the RJ45 connection, the PU3 connects the slave relay to the control unit affording the use of a second relay.

Slave relay
The PRE2000SR3 slave relay is a secondary relay unit. The slave relay is connected by either a low voltage wiring connection or direct connection to the PU3 using the supplied 300mm RJ45 patch lead.

Once connected to the PU3 the slave relay can be directly controlled via the control unit alongside the power unit, the slave relay has a 16A relay output to control the second element.

Tank temperature sensors
The PRE2000TTS-TR & PRE2000TTS-BB are temperature sensors for hot water tanks with either a foam or metal jacket. The TR is the top temperature sensor coloured red for easy and reliable identification. The BB is the bottom temperature sensor and is coloured black. The sensors incorporate a copper contact and isolated pressure spring covered by an insulating foam sleeve.

1.25ml of thermal paste is applied to both copper contacts to thermally bond the sensors to the copper surface of the hot water tank providing an accurate and consistent temperature reading. The copper contact is forced onto the tank by a spring, the spring is thermally isolated and insulated so as not to corrupt temperature readings. A high tack adhesive 0.55mm polycarbonate overlay is then applied over the sensor opening, compressing the spring, and forcing the contact onto the tank surface while resealing the insulating jacket.

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