A.O. Smith ADM - 115, Installation & Service Manual

Page: 51 / 74

Instruction manual ADM 51
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9 Starting and running
9.1 Introduction
Topics covered in this chapter:
•
Starting the appliance ;
• The appliance's heating cycle .
9.2 Starting the appliance
Start the appliance as follows:
1. Fill the appliance
(5 "Filling") .
2. Open (3.5 "Installation diagram") the manual gas
valve.
3. Switch on the power to the appliance using the
isolator between the appliance and the power
supply.
4. Put the appliance in ON mode by setting the
ON/OFFswitch on the control panel to position I .
5. Using the control thermostat (7.5 "Control
thermostat") , set the desired water temperature.
If there is a heat demand, the appliance will run
through the heating cycle
(9.3 "The appliance's
heating cycle") .
9.3 The appliance's heating cycle
The appliance's heating cycle is activated as soon as
the measured water temperature
(Twater
) falls below
the threshold value (T
set
). This threshold value
depends on the currently selected appliance operating
mode. For example, if the appliance is in OFF mode
(frost protection), then this value is 20°C. If the
appliance is in ON mode, for example, then this
threshold value can be selected, e.g. position 3 (±
60°C).
The heating cycle runs successively through the
following states:
1. HEAT DEMAND;
2. WAIT;
3. PRE-GLOW;
4. IGNITION;
5. RUNNING;
6. WAIT.
The entire cycle is explained in the example below.
Note
The cycle has the same steps when frost
protection is activated.
1. The control thermostat sensor measures the
temperature. The water temperature falls below
the set temperature of (for example) 60°C, causing
the control thermostat to close. The burner control
now detects a demand and starts the heating
cycle.
2. Following demand, the wait period starts. This wait
ensures that the ignition is safe. The wait period
lasts approximately 15 seconds.
3. Once the wait period has elapsed (there is audible
‘clicking’ of the relay in the burner control), the
PRE-GLOW starts.
4. After about 12 seconds (pre)glowing, the gas
control opens and ignition takes place.
5. After ignition, the flame is detected and the
appliance will be running. This means that actual
heating has started.
6. When the water reaches the set temperature, the
demand ceases. The gas control closes and the
burner tray is extinguished. A new wait period of
about 10 seconds starts.
7. At the end of this wait, the appliance enters the idle
state, and waits until the water temperature once
more falls below the set temperature.
With any subsequent heat demand, the heating cycle
will resume from step 1.