Rendama
Doc890/3456CV02B 15
2.2.1 Description of principal components
The unit is constructed from the following principal compo nents:
Fan [24]
This consists of a fan casing, a fan impeller and an electric motor. The fan sucks in combustion air
and increases the air pressure.
Air inlet damper [28]
A specially developed air inlet damper ensures a low noise level. As an option, this can be provid-
ed with an air fi lter or with an air inlet opening so that the appliance can function as a room sealed
appliance.
Gas train [13]
The principal component of the gas train is the main gas
valve/proportional pressure regulator [23]. The quantity of gas is adjusted in proportion to the
quantity of air being supplied. The quantity of air depends on the speed of the fan. The unit is fi t-
ted with a gas fi lter [11] as standard.
Mixing chamber [29 + 31]
This area is used for the thorough mixing of the gas and the combustion air. The unit is supplied
with a main mixing cham ber [29] and a pilot mixing chamber [31]. Both are connected to the fan.
Burner [9]
After the gas/air mixture has been distributed over the burner with the aid of a distribution plate
[8], the mixture is burned on the surface of the burner in such a way that the fl ame is di rected
downward. The burner is air and water cooled. The water distribution components are made from
cast iron and have a profi le that ensures that an optimum distribution and fl ow are obtained.
Heat exchangers [10, 12 and 17]
The primary heat exchanger [10] is constructed from smooth stainless steel tubes. These transfer
most of the heat energy to the system water. The secondary heat exchanger [12], which consists
of laser welded stainless steel fi nned tubes, transfers the remaining heat from the fl ue gasses to
the system water. All the water distribution components are constructed from cast iron and have
a profi le that ensures that optimum distribution and fl ow are obtained. The space between the
burner and the secondary heat exchanger forms the combustion chamber.
At the R3600 a third heat exchanger [17] is attached wich consists of one or more stainless steel
fi n tube(s), switched in series, in form of a spiral. It is arranged on the back of the boiler on the
fl ue gas collection chamber.
The boiler pump ensures the water fl ow quantity. The third heat exchanger is switched parallel to
the boiler and has a fl ow of 5 - 10 % of the entire water fl ow.
Water circulation pipes [15]
These pipes connect the burner to the heat exchangers.
Water connections
These consist of a fl ow connection [5] and a return connection [1]. Both of these connections are
provided with a fi lling/drain valve [6]. The fl ow connection is also provided with a safety valve [4],
a fl ow switch [3] and a temperature sensor.
Boiler pump [32]
The boiler pump is mounted on the return connection to the unit and is directly connected electri-
cally to the appropriate termi nals in the connection box. The capacity and the working head of the
pump is suffi cient to overcome both the resistance of the boiler and some system resistance.
Flue gas collection chamber [19]
The stainless steel fl ue gas collection chamber is mounted under the heat exchanger. This cham-
ber is provided with a fl ue gas exhaust connection [16], a condensate drain connection [22] and an
inspection opening.