Domestic hot water control:
p. 23
Using cooling functions
In addition to controlling heating, all WLM2 masters have the ability to control the system for cooling.
• To enable the cooling function an interface module WLAC and humidity sensor WLH have to be
connected.
• On BA masters it is also necessary to install a sensor (ETF-1899) on the return water pipework
from the floor for dewpoint control.
• The WLAC must be fixed in a convenient position for the user, and connected to the sensor/
controller bus as shown in the picture (pic).
• If a BMS system in being used for the heating/cooling decision, the volt free BMS signal should
be connected to WLAC but the slider switch on the right side of the WLAC must be set to the
heating position (in this situation the BMS signal has priority and we recommend that the slider
toggle be removed to avoid incorrect overriding)
• By using the humidity sensor WLH the system limits the formation of condensation on floor
surfaces due to high humidity.
• The WLH must be fixed in a room that represents the general humidity level in the building, and
connected to the sensor/controller bus (more than one WLH can be used if necessary e.g. on
separate floors of the building). Where more than one humidity sensor is used, the master will take
the reading of the sensor detecting the highest humidity level for the controlling action.
• If a dehumidifier is being used it can be connected via a relay using number 1 output on the master
and setting DIP-7 to “on”.
(Note: This output gives either 24Vac or 230Vac depending on the WLM2 master type. Channel
number 1 cannot be used for Room controller control in this situation)
• When cooling is enabled the cooling set point will be pre-determined by the master and will
override any settings in any Room controller to ensure optimum energy efficiency.
(The cooling set point will be +3C above the master day set point)
It is possible to control the domestic hot water temperature with a special Room controller (WLCT/
HW)to ensure optimum energy saving.
A hot water sensor is connected to the Room controller and measures the temperature in the storage
cylinder.
A zone valve is then controlled via the WLM2 master, which in turn activates the boiler on demand.
• Install the hot water senser (ETF) on the hot water take off pipe immediately above the storage
cylinder. Use the fixing strap to mount it tight to the surface.
• The WLCT/HW must be fixed in convenient position for the user
• Connect the hot water controller WLCT2/HW to the WLM2 master using the sensor/controller bus.
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