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4
Description of the product
4.1
General description
4.2
Operating principle
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,
Combustion products discharged through a concentric connector,
Front control panel with display,
Lightweight and compact.
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
System boilers can provide both heating and domestic hot water.
Domestic hot water will be heated in a separate cylinder or tank by the
system primary water via a submerged coil or similar.
The system controls will prioritise the production of either heating or
domestic hot water by the operation of a diverter valve in the primary
circuit.
With a demand for heating the pump circulates water through the primary
circuit. Once the main burner ignites the fan speed controls the gas rate
to maintain the heating temperature measured by the temperature sensor.
When the flow temperature exceeds the set temperature, a 3 minute
delay occurs before the burner relights automatically (anti-cycling). The
pump continues to run during this period.
When the demand is satisfied the burner is extinguished and the pump
continues to run for a period of 3 minutes (Pump Overrun).
4 Description of the product
800 System 2
19
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