© Aerionics 2018. All rights reserved.
Macurco is a trademark of Aerionics, Inc.
Carbon Monoxide

1. Where should I mount a CO detector in a home?

There are two usual sources of CO in homes – defective heat sources (furnaces and wood burning stoves) and
automobiles running in adjoining garages. For best protection mount the CO detector in the hallway near each
bedroom. In addition, another CO detector may be mounted just inside the door from an adjoining garage. Consider
placing another detector in a bedroom that is adjacent to a furnace room.

2. Should I place a CO detector in a residential garage?

Macurco does NOT recommend mounting a residential type CO detector in a garage. They are NOT intended for use
in parking garages or as the controller of exhaust systems.

3. What is the difference between a residential / office CO detector and CO detectors manufactured for
commercial applications?

CO detectors for residential and office use comply with standards set by Underwriters Laboratories (UL). Alarms from
these units usually cause evacuations or emergency unit dispatch. Macurco residential/ office units CM-E1 are
designed to meet this standard.

- Designed for use with a UL Listed Fire Alarm/Burglary Control Panel
- Listed to UL standard 2075 for the Standard For Safety for Gas and Vapor Detector and Sensors
- Tested to UL 2075 using UL 2034 Sensitivity limits for carbon monoxide gas.

CO detectors and controllers for commercial applications are manufactured to comply with standards set by national
organizations such as: the OSHA, NIOSH or Uniform Building Code. These units are designed to start ventilation at
lower concentrations and to alarm at higher levels.

4. What are the common standards for CO exposure?

The alarm points are: 70 ppm of CO after 60 to 240 minutes, 150 ppm of CO after 10 to 50 minutes, and 400 ppm of
CO after 4 to 15 minutes, in accordance with the provisions of UL Standard 2034.

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for carbon
monoxide is 50 parts per million (ppm) parts of air (55 milligrams per cubic meter (mg/m(3))) as an 8-hour time-
weighted average (TWA) concentration.

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit
(REL) for carbon monoxide of 35 ppm (40 mg/m(3)) as an 8-hour TWA and 200 ppm (229 mg/m(3)) as a ceiling [NIOSH

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned carbon monoxide a threshold
limit value (TLV) of 25 ppm (29 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH
1994, p. 15].


5. Is a CO detector used to detect the exhaust from diesel engines?

The toxic chemicals of most concern in diesel exhaust are the nitrogen oxides (NOx), sulfur dioxide, aldehydes,
primarily formaldehyde, acetaldehyde and acrolein. Nitric oxide or NO, is a problematic, short lived pollutant because it
converts to NO2 in the presence of oxygen. The higher average temperature of combustion of diesel engines
generates more nitrogen oxides than gasoline engines. Nitrogen dioxide or NO2  is one of the several nitrogen oxides.
At ordinary temperatures and atmospheric pressure, it is a reddish-brown gas with a characteristic sharp, biting odor.

6. What is the difference between carbon dioxide and carbon monoxide?

Carbon Dioxide CO2
A naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land-use changes and
other industrial processes. It is the principal anthropogenic greenhouse gas that affects the earth's radiative balance.

Carbon Monoxide CO
Carbon monoxide is colorless, odorless gas resulting from the incomplete combustion of hydrocarbon fuels. Carbon
monoxide interferes with blood's ability to carry oxygen to the body's tissues and results in numerous adverse health


Macurco has a full technical support staff to answer any installation and application questions that you may have about
our products. Technical support hours are 8:00 AM to 5:00 PM Central Standard Time.

Macurco products are sold through Wholesale Distributors in the Fire & Security, HVAC/R, Electrical, Safety and
Industrial markets. Please contact a professional contractor in these industries for pricing and availability of all Macurco products.
Frequently Asked Questions

1. What is the spacing for Macurco detectors?

Below is the typical spacing for detectors. This spacing is based upon an
open area with good airflow. Narrow hallways and areas where there is not
good airflow may require additional detectors.

         Residential: home, office, hotel, etc.
         Carbon Monoxide - one detector per 900 sq. ft.
         Heating Gases - one detector per 900 sq. ft.

         Commercial: parking garage, warehouse, etc.
         Carbon Monoxide – one detector per 5,000 sq. ft.
         Combustible Gases – one detector per 900 sq. ft.
         Nitrogen Dioxide – one detector per 5,000 sq. ft.

2. What is the mounting height for Macurco detectors?

The mounting height for Macurco gas detectors depends upon the type of
gas that you are trying to detect.

Carbon Monoxide:
  • Normally mounted at breathing level, about 4-5 feet above the floor.

Combustible Gases:
Mounting height depends on the molecular weight (density) of the gas.
  • Heavier than air (propane, LP, refrigerants): Low in the room, about one foot above the floor
  • Lighter than air (methane, natural gas, hydrogen): High in the room, about one foot below the ceiling.

Nitrogen Dioxide:
  • Normally mounted at breathing level, about 4-5 feet above the floor.
3. What gauge wiring does Macurco recommend?

Macurco recommends using the wiring sizes that are recommended by the National Electrical Code.

Distance of run - Wire Gauge

575 feet - 20 AWG
686 feet - 18 AWG
1300 feet - 16 AWG
2100 feet - 14 AWG
3200 feet - 12 AWG
3601 N St Paul Ave
Sioux Falls, SD 57104

Phone: 512-524-3414
Toll Free: 877-367-7891
Fax: 512-524-3415