ANSI/UL2075, and install the carbon monoxide alarms in accordance with either the standards of the National Fire Protection Association or the minimum protection designated in the manufacturer's instructions, which the landlord shall retain or provide as proof of compliance. A landlord that installs one carbon monoxide alarm per rental unit per level shall be deemed to be in compliance with standards under this subdivision covering the location and number of alarms. The landlord shall replace or repair the carbon monoxide alarms within 15 days of receipt of notification if the landlord is notified of needed replacement or repairs in writing by the tenant. The landlord shall ensure that a carbon monoxide alarm is operable and in good repair at the beginning of each tenancy. Unless the landlord and the tenant have a written agreement to the contrary, the landlord shall place new batteries in a battery-operated carbon monoxide alarm at the beginning of a tenancy, and the tenant shall replace the batteries as needed during the tenancy. Failure of the tenant to replace the batteries as needed shall not be considered as negligence on the part of the tenant or the landlord. A carbon monoxide alarm may be combined with smoke alarms if the combined alarm does both of the following: (i) complies with ANSI/UL2034 or ANSI/UL2075 for carbon monoxide alarms and ANSI/UL217 for smoke alarms; and (ii) emits an alarm in a manner that clearly differentiates between detecting the presence of carbon monoxide and the presence of smoke. This subdivision applies only to dwelling units having a fossil-fuel burning heater, appliance, or fireplace, and in any dwelling unit having an attached garage. Any operable carbon monoxide detector installed before January 1, 2010, shall be deemed to be in