Thermal device for a facility for heating and/or producing domestic hot water and/or air conditioning, the thermal device comprising: - a heat pump, and - a heat collector circuit that can be thermally connected to the heat pump and comprises: -- an auxiliary heat source, -- at least one underground collector, -- a heat transfer fluid, -- switching means for the thermal connection and thermal disconnection of the auxiliary heat source to and from the collector circuit, and -- circulation means suitable for circulating the heat transfer fluid in the heat collector circuit, the circulation means being suitable for circulating the heat transfer fluid in the heat collector circuit using a sequence in which, once the heat transfer fluid exits the heat pump, said heat transfer fluid first passes through the auxiliary heat source and then through the underground collector, the thermal device further comprising a second collector circuit that can be connected to the heat pump, the second collector circuit comprising: - at least one underground collector called cold collector, the cold collector being different from the underground collector of the heat collector circuit, - a heat exchange means suitable for cooling a piece of equipment, and - a second heat transfer fluid suitable for circulating in the second collector circuit, characterised in that the device further comprises a second heat pump comprising a condenser and an evaporator, the evaporator of the second heat pump being thermally connectable to the second collector circuit, the condenser of the second heat pump being thermally connectable to the heat collector circuit. - a heat pump, and - a heat collector circuit that can be thermally connected to the heat pump and comprises: -- an auxiliary heat source, -- at least one underground collector, -- a heat transfer fluid, -- switching means for the thermal connection and thermal disconnection of the auxiliary heat source to and from the collector circuit, and -- circulation means suitable for circulating the heat transfer fluid in the heat collector circuit, the circulation means being suitable for circulating the heat transfer fluid in the heat collector circuit using a sequence in which, once the heat transfer fluid exits the heat pump, said heat transfer fluid first passes through the auxiliary heat source and then through the underground collector, the thermal device further comprising a second collector circuit that can be connected to the heat pump, the second collector circuit comprising: - at least one underground collector called cold collector, the cold collector being different from the underground collector of the heat collector circuit, - a heat exchange means suitable for cooling a piece of equipment, and - a second heat transfer fluid suitable for circulating in the second collector circuit, -- an auxiliary heat source, -- at least one underground collector, -- a heat transfer fluid, -- switching means for the thermal connection and thermal disconnection of the auxiliary heat source to and from the collector circuit, and -- circulation means suitable for circulating the heat transfer fluid in the heat collector circuit, - at least one underground collector called cold collector, the cold collector being different from the underground collector of the heat collector circuit, - a heat exchange means suitable for cooling a piece of equipment, and - a second heat transfer fluid suitable for circulating in the second collector circuit,