Connecting The Dhw Sensor/Thermostat; Connecting A Frost Thermostat - REMEHA Avanta Range 24c Installation & Service Manual

Terminal
Block X9
1
2
3
DHW sensor (red band) or volt free thermostat (make on temp fall)
4
5
Exist
links
6
7
8
fi g. 26 Wiring diagram DHW calorifi er sensor or thermostat
LT.AL.W7H.000.031c
Terminal
Block X9
1
2
3
4
5
Exist
links
6
7
Modulating - using Open Therm control
eg: Honeywell Chronotherm or Celcia 20
On / Off - using simple volt free switching control
8
fi g. 27 Wiring diagram for frost thermostat
LT.AL.W7H.000.032c
X9
X9
25
2.7.6

Connecting the DHW sensor/thermostat

• If an external DHW calorifier is being used with the Avanta
Plus system boiler a volt-free DHW control sensor or ther-
mostat can be connected to connectors 3 and 4 of the X9
terminal block. The control will automatically detect whether
a sensor or a thermostat has been connected.
• For continuous DHW when using a combi boiler, the existing
link between connectors 3 and 4 of the X2 terminal block
must not be removed.
2.7.7

Connecting a frost thermostat

The boiler must be installed in a frost-free area to prevent the
condensate drain from freezing. However if the temperature of
the CH water in the boiler drops too low, the integrated boiler
protection device is activated as follows:
- at a water temperature below 7°C: the circulation pump is
switched on;
- at a water temperature below 3°C: the boiler is switched on;
- when the water temperature is above 10°C: the boiler is
switched off and the circulation pump runs for another
15 minutes.

• A frost thermostat should preferably be installed in rooms
with a high frost risk.
• Connect the frost thermostat in parallel to the room thermo-
stat - connectors 7 and 8 of the X9 terminal block (remove
existing link between connectors 7 and 8 before use).

If a 230 V switching time clock is connected to terminal block
X2, the frost thermostat wired as indicated (on connectors 7
and 8 of the X9 terminal block) it will not bring the boiler on if
the time clock is in the OFF position. In these cases the frost
stat must be connected in parallel with the time clock on con-
nectors 1 and 4 of the X2 terminal block (frost stat contacts to
close on temperature fall).

• The integrated boiler protection described above will not
provide complete system or fabric protection.
• When a Celcia 20 control has been fitted to connectors 7
and 8 on X9 (see Par. 2.7.4) an outside sensor as detailed
in Par. 2.7.5) must be used to provide system and building
fabric frost protection.
• If a frost thermostat is connected parallel to the Celcia on
connectors 7 and 8 on X9, when the frost thermostat calls
for heat (contact closed) it will override the Celcia 20 control
and cause an error message (OT ERROR) flashes in the
display and the boiler will operate continuously to achieve
the flow set point.