Auxiliary boiler systems, and methods of implementing and/or operating auxiliary boiler systems, are disclosed herein. In one example embodiment, an auxiliary boiler system for use in conjunction with a main steam source includes an auxiliary boiler, a deaerator coupled directly to and integrated with the auxiliary boiler, and a condensate storage tank coupled at least indirectly to the deaerator. Also, in another example embodiment, a method of implementing an auxiliary boiler system for use in conjunction with a main steam source includes setting a condensate storage tank in relation to a first support structure at a first position, and setting an auxiliary boiler at a second position. The method further includes directly coupling a deaerator to the auxiliary boiler so that the deaerator is integrated with the auxiliary boiler, and installing at least one interconnection by which the condensate storage tank is at least indirectly coupled to the deaerator.