State Water Heaters SCE 65-400, Installation, User And Service Manual

Page: 54 / 72

Putting into and out of operation
54 Instruction Manual SCE
7
gis
7.4 The appliance's
warm-up cycle
The appliance's warm-up cycle is activated as soon as the measured water
temperature (T
water
) falls below the threshold value (T
set
). This threshold value
depends on the selected state of the appliance. If the appliance is in the 'OFF
mode' (frost protection) then this value is 20°C. If the appliance is in the 'ON
mode' or 'Weekly program mode', then the threshold value can be set, for
example, position 3 (± 60°C).
The warm-up cycle runs through the following states in turn:
1. HEAT DEMAND;
2. WAIT TIME;
3. PRE-GLOW;
4. IGNITE;
5. IN OPERATION;
6. WAIT TIME.
The complete cycle is explained in the example set out below.
n
Remark
The cycle that has been completed also applies when switching on frost
protection.
1. The sensor for the control thermostat measures the temperature. The water
temperature falls below the set temperature (for example) 60°C and the
control thermostat closes as a result. The burner controller now confirms a
heat demand and starts the warm-up cycle.
2. The wait time period starts after the heat demand. This wait time ensures
safe ignition. The wait time lasts approximately 15 seconds.
3. When the wait time is complete (this can be heard by the 'clicking' of the
relay in the burner controller), the pre-glow starts.
4. After approximately 12 seconds of (pre)glowing, the gas control is opened
and ignition occurs.
5. After ignition the flame is detected and the appliance is in operation. This
means that the actual warm-up has commenced.
6. When the water is up to temperature, the heat demand is removed. The gas
control closes and the burner is extinguished. A new wait time of
approximately 10 seconds starts.
7. After this wait time, the appliance goes into its rest state and waits until the
water temperature once again falls below the set temperature.
At the next heat demand, the warm-up cycle restarts in step 1.