Stimmen - 1, Durchschnittliche Bewertung: 4 ( )

Hersteller: GE Dateigröße: 2 mb Dateiname: e79d889e-200b-4597-bb71-68a93d9c7390.pdf Unterrichtssprache:

The flue gases released by this combustion are led through the heat exchanger. The heat exchanger is composed of flue tubes that contain flue baffles. These retard the flow of the flue gases, thereby increasing the thermal efficiency of the appliance. The flue gases are exhausted from the appliance via the top box (46). The top box of the BFM 100 and 120 is non-standard (see box). An air distribution plate (50) mounted below the burner tray radiation shield also serves as a radiation shield. Any condensation that forms is drained towards the siphon via the air distribution plate. The PU insulation layer (24) prevents heat loss. The inside of the tank is enamelled to protect against corrosion. The anodes (9) offer extra protection. The entire appliance is controlled by the burner control (40) and the control thermostat (41) or frost thermostat (44). The control thermostat and frost thermostat both independently measure the water temperature (Twater). The appliance's heating cycle is activated as soon as Twater falls below the threshold value (Tset). The value of Tset depends on the selected mode of the appliance (8.2 "Operating modes"). When the appliance is in OFF mode (frost protection), this value is determined by the frost thermostat (threshold value = 20°C). When the appliance is in ’ON mode’, the threshold value can be set via the control thermostat (±40°C - ±70°C). The instant Twater falls below Tset, the appropriate thermostat (control or frost) will close, and the burner control will identify a heat demand. The gas control will open, and the gas will mix with air. This mixture is ignited by the spark igniter, and the water becomes heated. As soon as Twater rises above Tset, the thermostats will open once more. The heat demand is suspended, and the burner control stops the heating cycle. The thermostats have a certain margin both when opening and when closing. We refer to this margin as hysteresis. The hysteresis cannot be adjusted. Introduction The burner control monitors the water temperature by means of thermostats, and ensures that the combustion is safe. This takes place using: Instruction manual BFM 2 Working principle of the appliance gis • the Water temperature protection; • the Flame probe; • the Pressure switch. 2.4.2 Water temperature protection By means of the frost, high-limit and safety thermostats, the burner control monitors three temperatures that are important for safety. The table explains the working principle of the thermostats with sensors. Temperature protection Protection Description Frost thermostat When the frost thermostat sensor (46) measures a temperature of 20°C or less, the heating cycle (2.3 "The appliance's heating cycle") will start. High-limit thermostat When the high-limit thermostat sensor (39) measures a temperature higher than 84°C, the high-limit thermostat will open. The heat demand is terminated and the burner control halts the heating cycle until the high-limit thermostats close once more. At that moment the burner control will reset the appliance and the heating cycle will restart. The high-limit safeguard serves to prevent overheating and/or excessive formation of scale in the appliance. Safety thermostat When the safety thermostat sensor (38) measures a temperature higher than 93°C, the safety thermostat will open. The heat demand is terminated and the burner control will immediately halt the heating cycle. The burner control will go into a lockout error state. This must be manually reset before the appliance can resume operation. 2.4.3 Pressure switch The pressure switch ensures the discharge of flue gases and the supply of incoming air during the pre-purge and normal running of the appliance. The default state of the pressure switch is open. When sufficient pressure difference is reached, the pressure switch closes. However, in the event of a fault, the pressure switch is tripped open, and the heating cycle is interrupted. The table shows the trip point per appliance. Note The trip point of the pressure switch is not adjustable. Pressure switch trip points Appliance Closing pressure difference Opening pressure difference BFM 30 > 200 Pa < 170 Pa BFM 50 > 270 Pa < 240 Pa BFM 80 > 255 Pa < 225 Pa BFM 100 > 610 Pa < 580 Pa BFM 120 > 220 Pa < 190 Pa 2.4.4 Flame probe To ensure that no gas can flow when there is no combustion, the water heater is fitted with a flame probe (21). The burner control uses the ionisation-detecting properties of this probe for flame detection. The burner control closes the gas valve the instant it determines that there is a gas flow but no flame is present. Instruction manual BFM gis 2.5 Safety of the installation In addition to the appliance's standard built-in safety monitoring, the appliance must also be protected by an expansion vessel, expansion valve, pressure reducing valve, non-return valve and a T&P valve. The use of an expansion vessel, expansion valve and/or pressure reducing valve depends on the type of installation: u...

Herunterladen

Geben Sie zwei Ziffern: