DORCHESTER DR-FC 25, Инструкции по установке, пусконаладке и обслуживанию

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Functioning of the water heater
12 Instruction Manual DR-FC
2
gis
In this water heater the cold water enters the bottom of the heater via the cold
water inlet
n
. The tap water, heated by the combustion chamber
h
and heat
exchanger
k
, leaves the heater through the hot water outlet
b
. Once the water
heater is completely filled with water, it remains constantly under water supply
pressure. As hot water is drawn from the water heater, cold water is immediately
added.
The air required for combustion is forcibly delivered to the burner
q
by the
fan
r
. The gas is fed to the burner
q
via the gas control
p
. Thanks to the
modulated supply of gas and air, the optimum gas/air mixture is always
achieved. The special construction of the burner causes the mixture to form a
vortex (the cyclone effect), before it becomes ignited. Because of this vorticity,
ignition at the hot surface igniter
t
is improved, and the combustion efficiency
is also optimised. Through the special design of the heat exchanger
k
, the flue
gases are first led downwards via the combustion chamber, then upwards again
via the heat exchanger, then once more downwards beside the water in the
heater. In this process, the flue gases gradually become cooler. Because the
cooled flue gases flow alongside the cold water below in the heater, they start
to condense. This condensation causes latent heat energy to be released,
which is transferred to the cooler water, and thereby increases the performance
of the unit. The condensate yielded by this process is discharged via the
siphon
w
.
The PU insulation layer
x
prevents heat loss. The inside of the heater is
enamelled to protect against corrosion. The magnesium anodes
i
provide
extra protection against corrosion.
For use during maintenance, the water heater has a inspection and cleaning
opening
l
.
2.3 The water heater’s
heating cycle
The water heater is controlled (and monitored) by the control panel
d
. The
temperature sensor T
1
g
(in the top of the heater
j
) and the temperature
sensor T
2
m
(in the bottom of the heater) measure the water temperature.
These temperatures are sent to the control panel. Based on these two
observations, the control panel calculates a net water temperature: T
net
. The
value of T
net
lies between the temperatures measured at the top and bottom of
the heater. As soon as T
net
falls below the set water temperature (T
set
), the
control panel registers a ‘heat demand’. The gas control
p
is opened, and the
gas is mixed with air. This mixture is ignited by the hot surface igniter
t
and the
water becomes heated. As soon as T
net
rises above T
set
, the heat demand
ends, and the control panel stops the heating cycle.
Both when registering and ending the heat demand, the control panel assumes
a certain margin. We refer to this margin as the hysteresis (see paragraph
’9.2 Setting the hysteresis’ ).
2.4 Protection for the
water heater
The control panel monitors the water temperature and ensures safe
combustion. This is achieved by:
•
the Water temperature protection ;
• the Gas control ;
• the Fan ;
• the Pressure switch ;
• the Flame probe .