Device comprising a boiler mounted in a unit of furniture, which comprises: - the boiler comprising: - an intake for a heat-transfer fluid; - an intake for a fuel; - an intake for air; - a means for heating the heat-transfer fluid by combustion of the fuel; - an outlet for the heated heat-transfer fluid; - an outlet for combustion gases; - a means for fastening to a mount for moving the boiler along an axis within the unit of furniture; and - a handle for moving the boiler along an axis of movement of the movement mount from the interior of the unit of furniture towards the exterior of the unit of furniture and vice-versa; - the unit of furniture, for mounting the boiler, comprising: - at least one opening for a nonremovable supply duct for heat-transfer fluid, air and fuel, for supplying one boiler intake with heat-transfer fluid and one boiler intake with fuel; - at least one opening for a nonremovable exhaust duct for combustion products and heat-transfer fluid condensates, for evacuating the combustion products and heat-transfer fluid condensates generated by the boiler; and - a mount for moving the boiler, along an axis, so as to position the boiler either opposite the supply duct and exhaust duct, or at least partially outside the unit of furniture. - the boiler comprising: - an intake for a heat-transfer fluid; - an intake for a fuel; - an intake for air; - a means for heating the heat-transfer fluid by combustion of the fuel; - an outlet for the heated heat-transfer fluid; - an outlet for combustion gases; - a means for fastening to a mount for moving the boiler along an axis within the unit of furniture; and - a handle for moving the boiler along an axis of movement of the movement mount from the interior of the unit of furniture towards the exterior of the unit of furniture and vice-versa; - an intake for a heat-transfer fluid; - an intake for a fuel; - an intake for air; - a means for heating the heat-transfer fluid by combustion of the fuel; - an outlet for the heated heat-transfer fluid; - an outlet for combustion gases; - a means for fastening to a mount for moving the boiler along an axis within the unit of furniture; and - a handle for moving the boiler along an axis of movement of the movement mount from the interior of the unit of furniture towards the exterior of the unit of furniture and vice-versa; - the unit of furniture, for mounting the boiler, comprising: - at least one opening for a nonremovable supply duct for heat-transfer fluid, air and fuel, for supplying one boiler intake with heat-transfer fluid and one boiler intake with fuel; - at least one opening for a nonremovable exhaust duct for combustion products and heat-transfer fluid condensates, for evacuating the combustion products and heat-transfer fluid condensates generated by the boiler; and - a mount for moving the boiler, along an axis, so as to position the boiler either opposite the supply duct and exhaust duct, or at least partially outside the unit of furniture. - at least one opening for a nonremovable supply duct for heat-transfer fluid, air and fuel, for supplying one boiler intake with heat-transfer fluid and one boiler intake with fuel; - at least one opening for a nonremovable exhaust duct for combustion products and heat-transfer fluid condensates, for evacuating the combustion products and heat-transfer fluid condensates generated by the boiler; and - a mount for moving the boiler, along an axis, so as to position the boiler either opposite the supply duct and exhaust duct, or at least partially outside the unit of furniture.