DORCHESTER DR-LA 110, Руководство пользователя

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The water heater’s heating cycle
Instruction manual DR-LA 13
gis
hot surface igniter
z
ensures the ignition of the gas/air mixture. The flue gases
generated by this combustion are led through the flue tubes
d
. There are flue
baffles
e
located in the flue tubes. These slow down the flue gas exhaust,
improving the heat transfer efficiency. The flue gases leave the water heater via
the draught diverter
b
. A radiation shield/condensation tray
m
is mounted under
the burner tray. This prevents overheating of the floor surface under the water
heater and serves as a collection tray for condensate.
The insulation layer
h
prevents heat loss. The inside of the hot water tank is
enamelled to protect against corrosion. The anodes
c
provide additional
protection.
2.3 The water heater’s
heating cycle
The water heater is controlled by the burner control
q
and the control
thermostat
t
or frost thermostat
w
. The control thermostat and frost thermostat
both independently measure the water temperature (T
water
). The water heater’s
heating cycle is activated as soon as T
water
falls below the specified threshold
value (T
set
). The value for T
set
depends on the status chosen for the water
heater, see paragraph 6.2 Operating states . If the water heater is in the 'OFF
mode' (frost protection), then this value is determined by the frost thermostat
(threshold value = 20°C). If the water heater is in the 'ON mode', then the
threshold value is selectable via the control thermostat (40°C - 70°C).
As soon as T
water
falls below T
set
, the relevant thermostat (control or frost) will
close and the burner control will register a heat demand. The gas control
n
will
open and the gas will mix with the air it draws in. This mixture is ignited by the
hot surface igniter
z
and the water becomes heated. A soon as T
water
exceeds
T
set
, the thermostat will open once more. The heat demand will cease and the
burner control will stop the heating cycle.
The thermostats have a certain margin both when closing and opening. We refer
to this margin as the hysteresis. The hysteresis cannot be adjusted.
2.4 Protection for the
water heater
The burner control monitors the water temperature by means of thermostats
and ensures a safe combustion. This is achieved by:
•
the Water temperature protection ;
• the Combustion products discharge safety device ;
• the flame probe .
2.4.1 Water temperature protection
By means of the frost, high-limit and safety thermostats, the burner control
monitors three temperatures related to safety.
Table 2.1 explains the operation
of the thermostats with sensors.
Table 2.1 Temperature protection
Protection Description
Frost thermostat If the frost thermostat sensor
y
detects a temperature of 20°C or lower, the
water heater’s heating cycle will start. See paragraph 2.3 The water heater’s
heating cycle .
High-limit thermostat If the high-limit thermostat sensor
p
detects a temperature greater than 84°C,
the high-limit thermostat will open. The heat demand will be stopped and the
burner control will stop the heating cycle until the high-limit thermostat closes
again. At that moment, the burner control resets the water heater and the
heating cycle resumes. The high-limit safeguard serves to prevent
overheating and/or excessive formation of scale in the water heater.
Safety thermostat If the safety thermostat sensor
o
detects a temperature greater than 93°C, the
safety thermostat will open. The heat demand will be ended and the burner
control immediately stops the heating cycle. A lockout error will occur in the
burner control. This must be manually reset, before the water heater can be
put back into operation.