Velleman VMB1TC - Manual (Page 94)

94 VMB1TC Temperature controller manual – rev 5.0
DIFFERENTIAL THERMOSTAT
Using two sensors, a differential thermostat can be created. When the temperature difference between both sensors
crosses a preset value, a relay channel can be activated.
To achieve this, the first sensors must know the address of the second one. The second sensor must than be linked to a
relay channel. The temperature difference value is set on the first sensor.
To create a differential thermometer the set temperature difference is added to (or subtracted from) the measured
temperature of the first sensor and this value is than sent every 6 seconds as desired temperature to the second sensor.
The settings can be done via a temperature controller VMB1TC or via the Velbus link program
Schematic overview differential thermostat (sensor2 in heating mode):
SENSOR1 SENSOR2
t1
Set-up:
t2
Set-up:
Differential sensor address =
address sensor2 heating
Temp. Difference ∆t = -10°...10°
heating on when t1+ ∆t > t2
Measured temp t1 + ∆t
= Desired temperature for sensor2
Remark:
if t1+ ∆t > t
mode2
than desired temp. sensor2 = t
mode2
(mode2 = anti-freeze, night, day or comfort)
Schematic overview differential thermostat (sensor2 in cooling mode):
SENSOR1 SENSOR2
t1
Set-up:
t2
Set-up:
Differential sensor address =
address sensor2 cooling
Temp. Difference ∆t = -10°...10°
Cooler on when t1+ ∆t < t2
Measured temp t1 + ∆t
= Desired temperature for sensor2
Remark:
if t1+ ∆t < t
mode2
than desired temp. sensor2 = t
mode2
(mode2 = anti-freeze, night, day or comfort)
Refer to some applications of a differential thermostat below.