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Guide

How to Choose a Carbon Monoxide Meter

A CO meter shows the concentration live so you can find the source and judge the level. It is a different product from the alarm on the wall. This guide covers choosing a personal or investigative CO meter, and the home alarm that must be there regardless.

By the Akermin Editorial Team · 3 min read

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Choose a CO meter with an electrochemical sensor, a range of at least 0 to 500 ppm at 1 ppm resolution, a response time (T90) under 60 seconds, configurable low and high alarms (commonly 35 and 200 ppm) with sound, light and vibration, peak hold, and time-weighted average (TWA) and short-term exposure (STEL) readouts if it will be worn. Check the sensor life (2 to 3 years), whether it is replaceable, and whether the meter can be bump-tested and calibrated. For flue and appliance servicing, a combustion analyzer replaces the meter. In every case, keep certified CO alarms installed at home.

Types

Type Use Typical spec Examples
Personal single-gas CO monitor Worn by workers around engines, furnaces, garages; sounds alarms 0 to 500 ppm; TWA/STEL; 2-year sensor or 2-year disposable TOPTES CT-580 class; industrial single-gas monitors
Handheld CO meter Investigating a source in a home, garage, boat, workshop 0 to 1,000 ppm; 1 ppm; peak hold; logging on some Handheld ambient CO meters
Multi-gas detector with CO Confined space, industrial CO alongside O₂, LEL, H₂S TopTes Guard-101 class; see multi-gas detectors
Combustion analyzer Flue gas on boilers and furnaces CO to 8,000 ppm or more, O₂, temperature, efficiency Testo, Bacharach, Kane analyzers
Home CO alarm Continuous protection of occupants Certified UL 2034 / EN 50291; 7 to 10 year life Kidde and similar; see CO meter vs CO alarm

Specifications for a meter

  • Sensor: electrochemical; hydrogen-compensated if you work near charging batteries, since hydrogen causes false CO readings.
  • Range and resolution: 0 to 500 or 1,000 ppm; 1 ppm.
  • Response: T90 under 60 seconds; see why response time matters.
  • Alarms: low (35 ppm typical), high (200 ppm), with TWA and STEL for personal monitors; sound, light, vibration.
  • Peak hold and logging: peak for reporting; logging for a survey of an appliance cycle.
  • Sensor life and replacement: 2 to 3 years; replaceable cell preferred over a disposable unit for meters in regular use.
  • Bump test and calibration: compatible with CO calibration gas; see bump tests and calibration.
  • Build: IP rating, drop resistance, clip.

Reading the levels

CO (ppm) Meaning
0 to 9 Normal indoor background
10 to 35 Elevated; a source is present (traffic, gas hob, tobacco); investigate if sustained
35 to 70 Occupational 8-hour limits in this range; headaches with prolonged exposure
70 to 200 Alarms sound within hours; symptoms in most people within hours
200 to 400 Serious symptoms within 1 to 2 hours
Over 400 Life-threatening; leave immediately

Using a meter to find a source

  1. Zero in outdoor air; note the reading.
  2. Walk the building; note readings by room and near each appliance, flue, garage door and vehicle.
  3. Run each combustion appliance and watch the reading nearby for 10 to 15 minutes.
  4. Elevated readings near a boiler, water heater, stove or fireplace point to spillage or a flue problem; call a qualified engineer. Readings near an internal garage door point to a vehicle or a generator.

CO is not CO₂; see CO₂ vs CO. CO meters and alarms are in the gas detection category.

TOPTES CT-580 Portable Carbon Monoxide Detector, Rechargeable CO Detector with Vibration, Visual & Audible Alarms, 0-1000PPM, TFT Color Display for Home, Camping, Travel, Industrial & Professional Use

TOPTES CT-580 Portable Carbon Monoxide Detector, Rechargeable CO Detector with

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Kidde Carbon Monoxide Detector, AA Battery Powered, Portable for Travel or Home, 85 dB Alarm, LED Status Indicators, 3rd Edition

Kidde Carbon Monoxide Detector, AA Battery Powered, Portable for Travel

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TopTes Guard-101 Gas Detector, 4 Gas Monitor for H2S, CO, LEL and O2, with Vibration, Visual and Audible Alarms, 14h Long Battery Life, Safety Explosion-Proof, for Work, Home - Orange

TopTes Guard-101 Gas Detector, 4 Gas Monitor for H2S, CO,

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Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.

Frequently Asked Questions

What CO levels should a meter be able to read?

0 to at least 500 ppm with 1 ppm resolution covers investigation; 0 to 1,000 or 2,000 ppm for combustion and flue work. The dangerous range begins at tens of ppm sustained.

What is the difference between a CO meter and a combustion analyzer?

A CO meter reads ambient air. A combustion analyzer samples flue gas through a probe, reads CO in thousands of ppm, oxygen and temperature, and calculates efficiency. Heating engineers need the analyzer; investigators need the meter.

Does a CO meter replace my home CO alarm?

No. The alarm is certified to wake you and runs for years unattended; the meter is a handheld instrument. Have the alarm, use the meter to investigate.

Affiliate disclosure: Akermin earns a commission from qualifying Amazon purchases made through links on this page. Our editorial picks are based on documented specifications and owner feedback, not commissions.