<p>The invention relates to a boiler comprising a combustion chamber which is surrounded at least in part by a combustion gas flue that is embodied as a primary heat exchanger. The combustion gas flue is enclosed at least in part by a water-conducting housing while a water-conducting secondary heat exchanger that is hydraulically connected to the housing is mounted downstream of the combustion gas flue. According to the invention, the combustion chamber is surrounded at least in part by the secondary heat exchanger.</p>
