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  • 4-in-1 alarm protects against fast-flaming fires, smoldering smoke, carbon monoxide and natural gas (or methane).
  • 120-volt AC hardwired alarm with backup battery is suitable for houses, apartments and mobile homes.
  • Universal Sensing Technology responds 87-percent faster to slow smoldering fires and responds quickest to fast flaming fires.
  • Features a quick activation pull-tab and a front-loading battery drawer for replacement without removing the alarm from the bracket.
  • Comes with a 7 year limited warranty.
  • Revolutionary Universal Smoke Sensing Technology
Manuals

The USI Electric MDSCN111 Hardwired Smart Alarm is a 4-in-1 device that provides quadruple the protection with a single installation. This 120-volt AC alarm protects against (4) deadly household threats: fast-flaming fires, smoldering smoke, carbon monoxide and natural gas (or methane). Perfect for new or replacement installations, the MDSCN111 alarm is suitable for houses, apartments and mobile homes. Universal Smoke Sensing Technology responds 87-percent faster to slow smoldering fires and responds quickest to fast-flaming fires. Auto sensitivity calibration provides superior nuisance alarm protection and creates consistency in alarm sensitivity.

This 4-in-1 alarm has additional automatic features including: a self-diagnostics check to ensure proper operation, a sensitivity adjustment for changes in temperature or humidity and an end-of-service life warning that sounds when it's time to replace the battery. The 9-volt alkaline battery (included) continues protection in the event of a power outage. This combination alarm features a front-loading battery drawer for replacing the battery without removing the detector from the bracket. Mount the bracket to any standard wiring junction box and use the large mounting base to cover imperfections in drywall. For maximum protection, install an alarm inside every bedroom, outside every sleeping area and on all levels of the dwelling. The USI Electric MDSCN111 Hardwired Universal Smoke Sensing Smart Alarm comes with a 7 year limited warranty.

WHY DOES MY SMOKE ALARM 'CHIRP' APPROXIMATELY ONCE EVERY MINUTE?
The smoke alarm chirps to indicate a "low battery" condition, meaning the battery needs to be replaced. Battery powered smoke alarms will chirp a minimum of 30 days before the battery completely loses power.

AC powered smoke alarms with battery backup will chirp indefinitely assuming AC power is present; if battery power is low, or battery is removed; until a fresh battery is installed. Approved replacement batteries are listed on the back of each smoke alarm and in the user's manual.

Certain model smoke alarms with a silence button (designed to silence the alarm during a nuisance alarm) may chirp to indicate the smoke alarm is in the silence mode. The chirp will stop after approximately 8 minutes and the smoke alarm will return to its normal operation.
WHAT LEVELS (PPM) OF CARBON MONOXIDE CAUSE AN ALARM?
Carbon monoxide alarms are designed to alarm before the average healthy adult feels symptoms. Since you cannot see or smell CO, never assume it's not present. Underwriters Laboratories Inc. Standard UL2034 requires residential CO alarms to sound when exposure times and exposure levels of CO in the chart below. CO alarm levels are measured in parts per million (ppm) of CO over time (in minutes). The UL2034 Required Alarm Points are:
  • If the Alarm is exposed to 400 ppm of CO, it must alarm between 4 and 15 minutes.
  • If the Alarm is exposed to 150 ppm of CO, it must alarm between 10 and 50 minutes.
  • If the Alarm is exposed to 70 ppm of CO, it must alarm between 60 and 240 minutes.
IS CARBON MONOXIDE HEAVIER THAN AIR?
Carbon monoxide is not heavier than air. A carbon monoxide alarm should be installed in a location where the alarm will stay clean, and out of the way of children or pets. Refer to the user's manual for specific installation requirements.
WHAT DOES IT MEAN WHEN THE RED LIGHT ON THE ALARM FLASHES APPROXIMATELY ONCE EVERY MINUTE?
The flashing red light gives a visual indication that the smoke detector is functioning properly. It also indicates a working battery is connected to the smoke alarm.
WHERE SHOULD I INSTALL MY CARBON MONOXIDE ALARMS?
It is very important to install a carbon monoxide alarm outside each separate sleeping area, and for maximum protection, install one in every bedroom. Many states now require installation of a carbon monoxide alarm inside each bedroom. For added protection, placement of an additional carbon monoxide alarm at least 15-20 feet away from the furnace or fuel burning heat sources is recommended. Install carbon monoxide alarms a minimum of 10 feet from sources of humidity like bathrooms and showers. In multiple-story dwellings, install one carbon monoxide alarm on every level. If you have a basement, install a carbon monoxide alarm at the top of the basement stairs, and in each separate sleeping area.
WHAT AREAS SHOULD I AVOID INSTALLATION OF A CARBON MONOXIDE ALARM?
Do not install carbon monoxide alarms in garages, kitchens, furnace rooms, or in any extremely dusty, dirty, humid, or greasy areas. Do not install alarms in direct sunlight, or areas subjected to temperature extremes. These areas include unconditioned crawl spaces, unfinished attics, un-insulated or poorly insulated ceilings, and porches. Carbon monoxide alarms should not be installed in outlets covered by curtains, heavy furniture or other obstructions. Do not install in turbulent air-near ceiling fans, heat vents, air conditioners, fresh air returns, or open windows. Blowing air may prevent carbon monoxide from reaching the CO sensors.
WHAT DOES THE CONTINUOUS GREEN LIGHT ON MY SMOKE ALARM INDICATE?
When a green light is present on your smoke detector, it means that AC power is currently operating the alarm.
THE GREEN LIGHT ON MY SMOKE ALARM HAS GONE OUT, WHAT DOES THIS MEAN?
If the green light on your smoke detector is not on, it means the AC power has been interrupted to the alarm. Check the circuit breaker and AC wiring to make sure power is still reaching the smoke alarm.
HOW CAN I TELL WHICH SMOKE ALARM IN A MULTI-STATION SYSTEM INITIATED THE ALARM?
When interconnected alarms are alarming, the smoke alarm which initiated the alarm, either by test button or sensing smoke, will flash the red LED light approximately once per second. The red LED light on the other non-initiated interconnected smoke detectors will not be lit but will sound the alarm.
HOW MANY SMOKE ALARMS OR DEVICES CAN BE INTERCONNECT AT ONE TIME?
The NFPA 72 standard states the interconnect limit is 12 smoke alarms and up to 6 other alarms (heat alarms or carbon monoxide detectors) for a total of 18 total alarms. With 18 alarms interconnected, up to an additional 6 relay modules may be interconnected (for a maximum of 24 devices).

If battery backup alarms and non-battery backup alarms and accessories are mixed in an interconnect system, all devices without battery backup WILL NOT operate during an AC power failure.

CAUTION: USI alarms and accessories should only be interconnected with other USI alarms and accessories. Connecting devices from another manufacturer to USI devices may result in nuisance alarms, failure to alarm, or damage to one or all of the devices in the interconnect system. All interconnected USI alarms should be powered by the same fuse or circuit breaker. Smoke alarms shall not receive their power from a circuit that is protected by a ground fault circuit interrupter. Improper connection will result in damage to the alarm, failure to operate, or a shock hazard.
Product Details
Product Specs
UPC:
042741001113
MPN:
MDSCN111
Category:
Combination Alarms
Product Manuals

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62 Customer Reviews

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USI 4-in-1 Hardwired Smart Alarm with Smoke, Fire, CO and Gas Detection Reviews
Ralph D
September 19, 2023
Verified Purchase
Quick service

Yes, after placing my order I received my USI 4-in 1 smoke alarm in a very short amount of time. Much appreciated.

Alvaro G
January 26, 2023
Verified Purchase
Review

Your product is good, good thing I can find it on line, otherwise I would have had to change every unit thru the complex I give you all a big 5

David M
September 14, 2022
Verified Purchase
Model MDSCN111

Purchased this item to replace a unit previously installed by the builder of our home and that had reached its life end. The unit was extremely easy to install. Only had to change out the mounting plate. Michelle in customer service was extremely helpful when I called in to inquire about the new model number for this unit.

David H
August 22, 2022
Verified Purchase
Installation went smoothly

These 2 detectors replaced 2 older multi-sensor detectors that were reaching end of life. Everything needed came in the new boxes including mounting plates and wire assemblies. Smooth install in about 5 minutes each

John C
March 22, 2022
Verified Purchase
Safety first

I needed a whole house replacement for new construction detectors that were at end of life and got a good deal on upgraded 10 year battery models and got a few more carbon monoxide detectors to cover every bedroom and added a natural gas detector. Replacing the ceiling mount bracket and a couple wiring pig tails was not too hard. Very happy to not have to replace batteries and to have the best protection for my family.

Bridget L
March 18, 2022
Verified Purchase
Order confirmation

Very happy with my sales representative and the order I received.

Roger A
February 4, 2022
Verified Purchase
Great alarms that detect Smoke, Heat, Carbon Monoxide and natural Gas

I am so comfortable knowing that the alarms will detect all the hazards mentioned on the Review Heading. We have installed these on the three wood framed homes we have had since 1977 through today. While we have not had them go off in “anger” when we were asleep but we fell much better knowing we have these alarms on every room especially now that we are on our late 70s. They have each lasted over the 7 years stated and generally 8 years or more. We have also had a couple of friends during this who had fires in their homes which were not detected until the fires were really going but they luckily were unhurt but the damage was significant but not too bad. We have had gas cook stove where the pan overflowed and the gas flames were doused and gas was going into the house undetected. Thank God it was detected in time before we were gassed. It is so easy to be playing with the small kids and not smell the gas on another room in the house. A Neighbour jumped over our 6 foot fence between our yards as he realised the alarm was serious. These incidents detected early saved lives / damage to our kitchen. So thanks for the 4 in 1 alarms.

Nathan T
October 3, 2021
Verified Purchase
Easy Install

I purchased two 4 in 1 detectors. Replaced my old detectors and networked together seamlessly.

franco b
August 3, 2021
Verified Purchase

good product and went on easy

franco b
August 2, 2021
Verified Purchase

Easy to install

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