Powtier Controls Limited
505MST Thermostat
Instruction Manual
For example, using Table S1 (SW1=0, SW2=1). During the rising ambient temperature and at
15°C, the unit automatically switches to summer period; during a falling temperature and at
12°C, the unit automatically switches to winter period.
Table S1, Winter/summer setpoint switch
SW1
SW2
Winter
Summer
0
0
<9°C
>12°C
0
1
<12°C
>15°C
1
0
<15°C
>18°C
1
1
<12°C
>15°C(default value)
Note that the SW1 and SW2 setpoint switches will not be provided in the final production
units, as the temperature switching would be decided after the trial period.
Winter/summer LED indication
A green Led becomes illuminated to indicate a summer ambient temperature. This LED is
visible from the outside of the MST505/M unit, via the clear perplex window.
With reference to Table S1, the green LED becomes illuminated when the ambient
temperature reaches 12°C or 15°C or 18°C during the rising temperature.
The LED is off when the temperature falls below 9°C or 12°C or 15°C.
The LED is useful during testing and commissioning, as it is the only indication for ambient
temperature. For example, if the LED is off, it is in the winter switching condition and that
Table B is referred to (if SW3=0, SW4=1); if the green LED is on, Table A is referred to
(refer to Note 3 of clause 3).
Temperature setpoint switch
A PCB mounted, SW3 and SW4 parts of the 4-way (dual in line) switch is used for the
selections of temperature settings. There are three possible temperature settings, as shown
under Table S2.
Note that during the summer period (green LED on), the unit automatically refers to Table A
temperature settings.
Table S2, Temperature setpoint switch
SW3
SW4
Description
0
0
Table A
0
1
Table B
1
0
Table C
505MSTIM
Page 4
29 June 1998
Issue 1.0
