3
Electronic Programmable Room Thermostats
HC75-3 with integral sensor.
HC75A-3 with remote sensor.
USER'S GUIDE
How to:
Select a 12 hour or a 24 hour clock display.
Select a °C or a °F temperature display.
Change between Winter Time and Summer Time at the press of a
button.
Convert the HC75 to act as a thermostat, controlling at the selected
temperature continuously.
Use the HC75 as a frost thermostat.
Use the holiday function.
Override the programmed temperature.
Fig. 1. Display following a
RESET. - RUN mode.
(Colon blinking)
AUTO
HEAT
COOL
OFF
AUTO
ON
Fig. 2. Clock set to 12 hour
display.
AUTO
HEAT
COOL
OFF
AUTO
ON
DISPLAY ELEMENTS
(Those that will appear whilst following these user's instructions).
AUTO
HEAT
COOL
OFF
AUTO
ON
Holiday mode
selected
Temperature
override
indicators
Indicates
temperature
display
Boiler ON
indicator
Programmed HTG
temperature
indicator
Fan
running
indicator
Day of week
Clock time,
digital
thermometer, or
number of
holiday days
Programme
override
indicators
Frost
protection
mode indicator
Programmed CLG
temperature
indicator
SELECTING THE TEMPERATURE DISPLAY
(°C or °F)
The factory pre-set temperature display is °C. If a °F display is
preferred then press and hold down the
DAY
and
COPY
buttons until
the display changes. Repeat to return to a °C display.
SETTING THE CLOCK
Press
PROG
to display the time of day on its own (the display blinks).
Press
DAY
(the display stops blinking) to select today (1 = Monday, 6
= Saturday etc).Press and hold down the + or - button to change the
time quickly in ten minute steps, or press and release to change the
time by one minute.
When the day and time are correct, press and release
PROG
once to
start the clock and further press and release again until the colon starts
blinking, (RUN mode.) The intermediate stage is explained in the
Setting Instructions.
Heating/Cooling System Performance.
The HC75 includes one in-built and one optional comfort enhancement
feature that may have been enabled by your installer. Both will affect
the way in which the heating part of your system operates, and this will
be different from that provided by conventional time controls and room
thermostats.
The in-built feature is an intelligent electronic anticipator which measures
the rate of temperature rise then switches the heating plant off before
the set temperature is reached. However the required comfort
temperature will be reached due to the residual heat in the system after
the heating planthas shut down. This feature is only activated when the
space temperature is 2°C or more lower than the set temperature.
If the optional Chrono-proportional feature has been enabled, then the
heating plant will operate at regular intervals to prevent the large
swings in space temperature caused by heat emitters alternating
between very hot and cold. In mild weather and when the system is up
to temperature the heating plant may operate only in short bursts with
long periods of inactivity. This is not a fault, and will provide increased
comfort.
RUN MODE
Whilst the HC75 is in RUN mode, i.e. controlling the space temperature
in accordance with the programme, the colon between the hours and
minutes digits blinks. The colon does not blink whilst the time and
programme are being set.
SELECTING THE CLOCK TYPE (12hr or 24hr)
The factory pre-set clock has a 24 hour display. If a 12 hour display
with AM/PM indication is preferred then press and hold down the
NEXT
and
DAY
buttons until the display changes. Repeat to return to
a 24 hour display.
Fig. 3. Temperature range
changed to Fahrenheit.
AUTO
HEAT
COOL
OFF
AUTO
ON
Fig. 4. Clock time ready for
changing.
(Colon steady, digits blinking).
AUTO
HEAT
COOL
OFF
AUTO
ON
