OSO DGC 200 Installation Manual page 6

6.3 Motorised valve
To comply with regulations governing the installation of indirect unvented cylinders, a motorised valve must be fitted in
the primary pipework. Your OSO unit has been supplied with a two port motorised valve, which will act as a positive
energy cut-out should the safety cut-out operate. The motorised valve will also control the temperature of the
domestic stored water via the cylinder thermostat, which is located in the electrical box. The unit can be installed on an
"S" or "Y" plan system. Please follow the wiring instructions carefully.
6.4 Digital Dual Cylinder Thermostat
The Digital Dual Cylinder has real safety and energy saving benefits and provides accurate temperature control. It
also features a clear and informative LCD display. Leave the cylinder thermostat set at 60°C in line with current
government guidelines. Lowering the temperature will substantially reduce the amount of usable hot water available
on a daily basis and could result in bacterial growth unless the legionella facility is activated (THIS FUNCTION IS
ACTIVATED AS STANDARD see label on side of thermostat, for commissioning purposes please disable this
function selecting OF in display see 6.4.1 below).
The legionella mode gives a weekly automatic one hour "boost" to above 60°C which kills any legionella bacteria,
This function is adjustable allowing the duration of the legionella override to be adjusted from 1 to 7 days or
completely disabled to operate as a conventional Dual Cylinder Thermostat. The LCD display shows the current
water temperature and the user defined water temperature, while the red LED indicates that the unit is calling for
heat. The sensitive electronic sensors operate at a far greater accuracy than conventional thermostats. The dial
makes it easy to set the required controller temperature (between 25°C and 65°C) .The second (limit) safety
thermostat is pre-set to 80°C with a concealed manual reset, to comply with building regulations. Should the
safety cut out be brought into operation, the motorised valve will operate and close down the primary flow
to the cylinder. To reset the safety cut-out and the motorised valve the reset button must be pressed in.
Wiring Diagram
6.4.1 Adjusting the 1 Hour Boost
The thermostat has user defined settings where the duration of the legionella Override/Boost can be adjusted from 1
to 7 days or completely disabled to operate as a conventional dual cylinder thermostat.
1. To disable or adjust he legionella override/ boost turn the unit off by pressing and holding down the HOLIDAY
button until an audible click is heard.
2. Release the button and after approx. 10 seconds press and hold the holiday button again until an audible click is
heard and the LCD display flashes
3. Release the button and use the HOLIDAY button to choose between disabling the override/Boost (OF in
display) or setting delay between boost/override from 1 - 7 days (1-7 in display)
4. Once selected release the button and the unit will return to the user set position within 5 seconds
6.4.2 Holiday Mode
This is the black button located under the display. Press and hold the holiday switch
for a minimum of 10 seconds until you hear an audible click, and this switches the
digital Dual Cylinder Thermostat off completely so there is no water heating and no
weekly "boost" heating.
When in Holiday mode, the display is off. This feature should only be used when the
property is vacant for extended periods and there is no requirement for water heating
or for the weekly "boost". Pressing and holding the holiday switch again (for a
minimum of 10 seconds until you hear an audible click) will restart the Electronic
Dual Cylinder Thermostat, the display will show the cylinder temperature and the
weekly
"boost " will immediately start, and recur every 7 days at the same time depending on
the user set position.
If using a 6-wire 28mm or 1" BSP V4043H on either circuit the white wire is not needed and must be made
electrically safe.
OSO Hotwater (UK) Limited can not be responsible if alternative wiring plans are used. Important: Before
resetting the safety cut-out or altering the thermostat setting isolate electrical supply to the unit before
removal of the lid
INDIRECT HEATING SYSTEM
Also see S-Plan and Y Plan Wiring page 7 and 8
This product requires a fused permanent Live and Neutral
supply.
Holiday
Mode
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