An older Seattle house may stay quiet for years, then begin sounding alarms in the middle of the night after a remodel, especially when all the smoke and carbon monoxide units were replaced at once. In that situation, the trouble usually traces to wiring, interconnect setup, power quality, or placement rather than the alarm brand.

In the case described here, the home had no false alarms before the remodel, and the newer units are hardwired interconnected First Alert models using photoelectric sensing. The remodel is the clearest turning point, tied to new wiring, a different layout, or a new spot for one or more alarms.

A licensed electrician makes sense as the first call for hardwired alarms, because interconnected units depend on correct wiring and steady household power. Irregularities in the AC supply are one possible cause worth ruling out before anything gets replaced again.

Placement can matter just as much. A detector installed too close to a bathroom, kitchen, vent, or airflow change caused by the remodel may be prone to nuisance alarms, particularly overnight as indoor temperature and air movement shift through the house.

The practical fix is a full walk-through: trace the alarm circuit, inspect the interconnect wiring, make sure the units are compatible, and see whether any detector now sits in a spot that raises the odds of false trips. In an older house with newer finishes, alarm problems usually come from how the system was fitted into the remodel rather than from a dead battery or the need to replace every unit.