An Electronic Control Unit for spas
was developed as a substitute for the analog systems. This allows for
more reliable switching and temperature control.
LIQUID CRYSTAL DISPLAY:
A four line / 20 character display allow for a friendly user
interface. A build in back-light will ensure that the information on the
screen will be clearly displayed even in the dark.
Keypad buttons allow for the setting of temperature, the clock and
THERMOMETER - Shows at all times the current temperature of the
water in the spa.
THERMOSTAT - By first selecting - Temp - then by selecting the
- Up or Down - buttons the water temperature can be increased or
decreased to the desired temperature.
Circulation times - A menu will allow for the start and
ending times for circulation. If the start and ending times are
set with the same time the spa will circulate
on a 24 hour basis. The water temperature will be regulated at
the set temperature. For circulation only, without heating up
the water, the set temperature is decreased below tap water
Function buttons allow for the Circulation pump, Turbo pump, Blower
and Light to be switched on or off. Depending on the installed
components i.e. a turbo pump or light some of the function buttons may
not be active. Light emitting diodes to the left on the control panel
will show when functions are switched on or off. The heater will
automatically be switched on or off depending on the water temperature
and the temperature Set.
Low voltage (+5v DC) is used at the Processor Unit, making it
All high voltage switching is done on the relay board that is placed
in he protective environment of the Distribution Box.
ADVANTAGES (above that of the analog systems):
More compact - There is only one Control Interface and Large
bellow buttons with air switches and air pipes are not needed.
Build-in Timer - By using a Swimming pool digital
timer a contactor is needed for switching due to the high load of
element. With the Digital Control Unit all switching is done through
relays which are rated far above the load it has to comply with.
Build-in Thermometer - The user can monitor water
temperature at all times.
Thermostat - Water temperature can be regulated to one degree
Celsius. The analog thermostats are rated accurate to 5% up or down.
With these thermostats the spas must first me heated to the desired
temperature, then a mark must be made on the thermostat dial to
ensure that the next time the spa can be heated to the same
temperature. When the air valve is opened or the blower switched on
the heater will switch on quicker keeping the water temperature
Safety - The water temperature is measured in the heater casing.
Should there be a sudden increase (2 degrees or more) in temperature
or a temperature increase more than 45 degrees (due to a lack of
water on the heater element) the Control Unit will shut the spa down
preventing damage or possible fires.
The relay board is fitted in the enclosed environment of the
Combo Distribution Box and Heater casing. The thermostat is placed
at the optimum position to calculate the temperature as accurate and
as quick as possible. If the thermostat becomes faulty or a wire
becomes damaged no flow of data will occur between the thermostat
and the Control unit and the spa will shut down. Capacitors protect
the contact points of the relays from arcing in very much the same
way as a condenser would do over the contact points in the
distributor of a car.
Cat 5 cable with RJ45 connectors are used for data transfer
between the Control Unit and the relay board thus allowing for
longer distances between the Control and pump units.
Paradise Spa developed the Electronic Control Unit and all blue
prints belongs to Paradise Spa. Further developments can be made
without the involvement of third parties.