12
2.6
Description of the most important boiler parts
1. Fan
The fan is a compact unit: the motor and fan housing are an integral part and can be replaced as a complete unit.
The fan varies in speed due to the boiler control, which ensures that the modulation of the boiler is attained.
2. Gas train
The boiler has two equal gas control valves (one for each burner).
Both gas control valves have two main gas valves internally that are opened simultaneously. When there is a heat
demand, modulation takes place under the influence of the fan speed variation. The correct amount of gas is sucked
in, by creating an under pressure through the fan, from the gas control valve.
3. Mixer
There is a mixer on the suction side of the fan(s) in which the gas and air are mixed together until a uniform gas/air
quantity is obtained. This is pushed into the burner.
4. Boiler pump
(not in drawing on this page)
The separately supplied boiler pump must be connected to the return of the boiler. The head of this pump must be
sufficient to overcome the boiler resistance and the external system resistance for a connection to a low loss header.
5. Burner control
The boiler has two equal burner controls: one for each burner unit. One of the burner controls has a built-in cascade
manager for the overall control of the boiler.
6. Electrical connections
All electrical components can be connected at the rear/top of the boiler. A relay has been installed to give power to
the boiler pump.
