4 Description of the product
4.1
General description
The purpose of this gas-fuelled condensing boiler is to heat water to a
temperature that is lower than boiling point at atmospheric pressure. It
must be connected to a heating installation and to a domestic hot water
distribution system that is compatible with its power and performance
ratings. Features of this boiler:
Low pollutant emissions,
High-efficiency heating,
Front control panel with display,
Lightweight and compact.
4.2
Operating principle
4.2.1
Air-gas adjustment
The air is drawn in by the fan and gas injected directly at the height of the
venturi. The fan revolution speed is regulated automatically by the
electronic board based on the adjustment settings. The gas and air are
mixed in the manifold. The gas/air ratio ensures that the quantity of gas
and air are adjusted correctly to always obtain optimal combustion. The
gas/air mixture is fed into the burner at the front of the exchanger.
Here, the electric igniter triggers the mixture with a series of sparks that
burn, producing thermal energy.
4.2.2
Combustion
The burner heats the heating water circulating in the heat exchanger.
When the temperature of the combustion gas is lower than the dew point
(around 55 °C), the water vapour contained in the combustion gas
condenses in the flue gas side of the heat exchanger. The heat recovered
during this condensation process (the latent heat or condensing heat) is
also transferred to the heating water. Once cooled, the combustion gases
are discharged through the exhaust pipe. The condensed water is
discharged through a siphon.
4.2.3
Heating and domestic hot water production
In boilers used for heating and for producing domestic hot water, an
integrated plate heat exchanger heats the domestic water. The heated
water is then channelled to the heating installation or to the plate heat
exchanger via a three-way valve. A flow sensor detects that a hot water
tap has been turned on and communicates this to the PCB, which
switches the three-way valve to the hot water position and activates the
pump. The three-way valve is spring-loaded and only consumes electricity
when switching from one position to another. Precedence is given to a
heat request in domestic water mode.
4 Description of the product
12
400 Combi 2
