Protective Device for a Boiler Access Point

A protective device for a boiler access point in a boiler wall, comprising:

• a fan;
• a check valve;
• a pressure sensor;
• a gas-light connection having a pressure sensor and an ambient outlet;
• a pressure hose;
• and
• a control unit connected with the pressure sensor,
• wherein the fan having an access is connected via the access to an environment for drawing in ambient air,
• wherein the check valve is connected downstream of the fan via the gas-tight connection,
• wherein the check valve is connected via the pressure hose to the boiler access point leading through the boiler wall,
• wherein the check valve closes at a first fluid pressure present at the pressure hose if the first fluid pressure is greater than a second fluid pressure present at the fan, wherein the control unit comprises a data memory in which at least a lower first and a higher second threshold value for pressure values are stored,
• wherein a presence of a malfunction in a malfunction range is detected by the control unit when a pressure sensor signal measured by the pressure sensor and forwarded to the control unit is below the first threshold value, and
• wherein the presence of a malfunction in an overpressure range is detected by the control unit when the pressure sensor signal measured by the pressure sensor and forwarded to the control unit is above the second threshold value.