Sensor and housing arrangement for gas analysis

A combustion apparatus comprising:

• a combustion chamber;
• and
• an exhaust in fluid communication with the combustion chamber, wherein the exhaust comprises a wall and a gas stack and/or flue gas stack and/or chimney;
• a sensor unit;
• a housing with a first end, a second end, a plurality of inlet openings, and an outlet opening;
• a pair of electrical leads;
• and
• an attachment apparatus for a fixed mechanical attachment of the housing to the wall of the exhaust;
• wherein at least one electrical lead of the pair of electrical leads extends from the sensor unit to the attachment apparatus;
• the outlet opening is not one of the plurality of inlet openings;
• the sensor unit is arranged at least partially inside the housing at a first distance from the first end and at a second distance from the second end;
• the first distance is greater than the second distance;
• the outlet opening is at a third distance from the first end and a fourth distance from the second end;
• the third distance is greater than the fourth distance;
• and
• the attachment apparatus is mechanically mounted to the wall.