Powtier Controls Limited
505MST Thermostat
Instruction Manual
Lower level damper solenoid (LLDS)
The LLDS is energised to close the damper whilst in the "Vent" or "Cooling" stages.
The LLDS is energised when the VENT LED is ON. LLDS is de-energised when the VENT
LED is OFF.
During rising temperature, when heater 1 (H1) is switched OFF, the LLDS is immediately
energised.
LLDS time delay
During falling temperature, from "Vent on", to "Heater 1 on"; there is a time delay before the
LLDS could be de-energised, that is "Vent off". If however, in the event that the saloon
temperature rises again above the "H1 off", the timer would be reset to zero and that the LLDS
would remain energised.
The time delay is adjustable between 30 to 158 seconds using a 25-turn encapsulated
potentiometer. Clockwise adjustment increases the time delay.
The LLDS time delay potentiometer is located on the top left-hand corner of the PCB, easily
identified with the following legions on the PCB (please refer to Internal board layout diagram
for detail):
PT
FULLY CW - 120 SEC
FULLY CCW - 30 SEC
Note: CW indicates ClockWise. CCW indicates Counter ClockWise.
IMPORTANT
It is important to note that the time delay PT potentiometer is the only potentiometer which is
user adjustable.
DO NOT adjust the other three potentiometers, PA, PS and PZ - these are used for factory
calibration adjustments.
505MSTIM
Page 5
29 June 1998
Issue 1.0
