Can't get boiler to stop heating! It's 80 degrees in the house
If this is a hydronic heating system using wax zone valves, which act both as water valves and as thermostat, these sometimes fail in the &quot;on&quot; position. If that is the case, disconnect one of the wires from the switch.
That said, as @Ecnerwal states, there is a serious issue with wiring if the boiler still fires with the safety switch &quot;off&quot;. Is there perhaps another shut-off switch??