AlphaStat-Plus Users Guide.
Your AlphaStat-Plus has a microcomputer at its core that intelligently and automatically controls your hot
water system at greater efficiency. The AlphaStat-Plus measures the cylinder water temperature and turns
on the element at the optimum time.
The AlphaStat-Plus allows intelligent control of the electric element used in the hot water tank. The AlphaStat-
Plus can prevent the electric element coming on while you are on holiday (‘Away’ mode), maintain an
efficient temperature in your hot water cylinder using two user-configurable reference points (Reheat) and
ensure that safe water conditions are maintained (BioSafe) and a one off heat up (Demand). These controls
will save a considerable amount of electricity.
The AlphaStat-Plus has advanced features that protect the system from damage, run self diagnostics, self
correct some problems and will keep you informed as to what the AlphaStat-Plus is measuring and what
decisions it is making.
Principle of operation.
The hot water tank sensor is called: ‘TANK’
The upper temperature threshold is called: ‘SET OFF’
The lower temperature threshold is called: ‘SET ON’
The AlphaStat-Plus is a HWC electric element controller. The controller measures the temperature at the
‘TANK’ sensor and compares this to the ‘SET ON’ threshold. If the tank is below this threshold, then the
element is turned on and heats the water in the cylinder. Once the tank has reached the ‘SET OFF’
threshold, the element is turned off to save power.
The AlphaStat-Plus has other special features to those mentioned above.
The Demand mode is where the user can initiate an immediate reheat of the cylinder for times when
there will shortly be a heavy draw off of. This will heat the cylinder to a factory- or installer- defined
‘Demand’ value (60C standard) which will normally be higher than the regular ‘SET OFF’ target temperature.
The BioSafe mode is to prevent the growth of dangerous organisms within the hot water cylinder.
The cylinder must reach a preset temperature (60C standard) at least once every 72 hours. If this does not
happen, the element is turned on and held on until a safe temperature is reached.
The ‘AWAY’ function is to allow for long periods where electric boosting of the hot water is not
required. Pressing the ‘AWAY’ button prevents the cylinder from turning the element on. This takes
precedence over all other functions . To leave ‘AWAY’ mode, simply press the ‘AWAY’ button again.
NOTE: Senztek NZ Ltd recommends that when the ‘AWAY’ button has been turned on and then off sometime
later, no hot water be drawn off until the Biosafe light goes off. This is to ensure that the water has been
heated up to safe level.
Sensor diagnostics: The AlphaStat-Plus constantly checks the sensor. If the sensor is below -20C
the display reads ‘Lo’. If the sensor is above 140C the display reads ‘Hi’. If the sensor is outside the
specified temperature range of -40C to 150C then the Display reads ‘SSd’ and the controller enters Smart
Shutdown mode. When the display reads ‘SSd’ the sensor has either a steady light for a temperature above
150C (possibly shorted sensor or wire) or a flashing light for a temperature below -40C (possibly open
sensor or broken wire). For example if the sensor wire is cut during some building work then the AlphaStat-
Plus display reads ‘SSd’, the ‘Tank’ light flashes and the controller enters Smart Shutdown mode until the
wire is repaired.
Smart Shutdown (SSd): In Smart Shutdown mode, the Display reads ‘SSd’ and the element is held
on to ensure hot water. The Hot Water Tank Temperature will be controlled by the Hot Water Tank Thermostat
for the electric element.
Test: Briefly pressing this button will cause all the lights to flash on for 3 seconds then display for 3
seconds the number of times the element has been on. This count will reset and start again after ‘999’.
19.08-4
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