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Ei Electronics - Fire and Gas Detection. Smoke, Heat and CO Alarms. eSeries Smoke and Heat Alarms Ei141e, Ei144e, Ei146e, Ei2110e Multi-sensor Alarm. Carbon Monoxide Alarms.

Carbon Monoxide FAQ's

This section provides answers to Frequently Asked Questions about Ei Electronics Carbon Monoxide alarms.
What are the "Deadly Facts" about Carbon Monoxide

Click here to download vital information regarding Carbon Monoxide

Is there a single document containg a comprehensive list of Carbon Monoxide (CO) FAQ's?

Click here to download a comprehensive set of Carbon Monoxide (CO) FAQ's.

What is Carbon Monoxide?

Carbon Monoxide (CO) is an invisible, odourless, tasteless & extremely toxic gas. CO is a result of incomplete combustion of fossil-fuels such as natural gas, bottled gas, solid fuels (wood, coal etc). CO is absorbed by the red blood cells in the lungs in preference to oxygen, resulting in oxygen starvation & rapid damage to the heart & brain.

Here are a few UK statistics that will set the alarm bells ringing:

  • 23 deaths from Carbon Monoxide poisoning in 2009/2010
  • 176 near misses from Carbon Monoxide poisoning in 2009/2010
  • 72% of Gas Safe (formally CORGI) registered engineers discovered a Carbon Monoxide leak when performing routine services on appliances
  • 40% of recorded Carbon Monoxide incidents were caused by bad installation and repair of appliances

However, incidents of Carbon Monoxide poisoning are often unrecorded as they can easily be misdiagnosed – low level exposure to Carbon Monoxide results in symptoms similar to flu. Due to this the actual number of poisoning incidents is almost certainly much higher than the figures shown above.

CO is produced by any fossil-fuel burning appliances such as gas or oil boilers/furnaces, gas/solid fuel fireplaces, gas appliances, solid fuel stoves etc. Heavy doses of CO will cause a person to collapse & die within minutes [see adjoining table]. Lesser doses of CO may cause flue-like symptoms, headaches, drowsiness, fatigue, nausea, vomiting [see table below].

Sources of Carbon Monoxide

If a home has any of these appliances it is a potential source of Carbon Monoxide.


Toxic amounts of CO can be produced if there is:

  • An appliance not working correctly due to poor installation, lack of servicing or blocked chimney or flue.
  • Inadequate ventilation, resulting in insufficient oxygen for the fuel to burn properly.
  • A cracked chimney or flue.

Where to place Carbon Monoxide Alarms

CO Siting

Table A Effects of Cumulative CO Exposure
CO ppm Inhalation Time (approx) and Symptoms Developed
35 The maximum allowable concentration for continuous exposure in any 8-hour period according to OSHA**.
150 Slight headache after 1.5 hours.
200 Slight headache, fatigue, dizziness, nausea after 2-3 hours.
400 Frontal headaches within 1-2 hours, life threatening after 3 hours.
800 Dizziness, nausea and convulsions within 45 minutes.Unconsciousness within 2 hours. Death within 2-3 hours.
1,600 Headache, dizziness and nausea within 20minutes. Death within 1 hour.
3,200 Headache, dizziness and nausea within 5-10 minutes. Death within 25-30 minutes.
6,400 Headache, dizziness and nausea within 1-2 minutes. Death within 10-15 minutes.
12,800 Death within 1-3 minutes.
OSHA ** Occupational ppm
Safety & Health Association parts per million


If the CO Alarm gives a warning you MUST believe that Carbon Monoxide is present (because it is invisible, odourless & tasteless you cannot verify!) and you MUST take immediate corrective action.
[see panel below “What to do if Carbon Monoxide is detected”].

What do you do if Carbon Monoxide is detected

  • Turn off all fuel burning appliances
  • Open doors and windows to ventilate.
  • Leave the property.
  • Contact your appliance service company
  • If in doubt contact the emergency services for advice
  • Don’t re-enter the property until the alarm has stopped
  • Don’t use appliances until checked by a qualified person.

What are the effects of exposure to CO Gas?

CO is absorbed by red blood cells in the lungs, in preference to oxygen – this results in oxygen starvation. Heavy doses of CO will result in rapid damage to the heart and brain and cause a person to collapse and die within minutes. Lesser doses can cause headaches, fatigue, nausea or flu-like symptoms.

What are the sources of Carbon Monoxide?

Toxic amounts of CO can be produced if there is:-
  • Inadequate ventilation, so there is insufficient oxygen for the fuel to burn properly.
  • Blocked or damaged flues or chimneys.
  • An appliance not working properly because of poor installation or lack of servicing.

What types of fuel burning appliances can be a source of CO?

Types of fuel burning appliances can be a source of CO:
  • Gas Boiler or Furnace.
  • Oil Burner or Furnace.
  • Gas Cooker
  • Solid Fuel / Oil Stove.
  • Gas Fuel Fire Place.
  • Solid Fuel Fire Place.
  • Portable Gas or Paraffin Heater.
  • Does the CO Alarm sound different to a smoke Alarm?

    Yes, the alarm from a CO Alarm is the Evacuation-tone, 3 beeps – off – 3 beeps.

    How many alarms do I need and where do I install them?

    It depends on the level of protection you wish to have.
  • Ideally you should have 1 in or near every room that has a fossil-fuel burning device.
  • Desireable to have 1 in the Main Living Room.
  • Recommend to have 1 in the Main Bed Room.
  • Where do I locate/position the CO Alarm in the room?

    (a) Room with the fuel burning device.
  • Locate above the level of doors/windows.
  • On wall or ceiling, minimum of 1 metre from the appliance.
  • Keep away from any vents, windows, doors.
  • (b) Other Rooms.
  • Locate at breathing height.
  • (c) Bedrooms.
    Locate at bed-height.

    Are there different types of CO Alarms?

    Yes, there are battery powered and mains powered CO Alarms.

    In the Ei Electronics range, the following models are available.



    To Install


    Battery Powered

    Easily installed by Householder


    Battery Powered with Memory

    Easily installed by Householder


    Battery Powered with Digital Display

    Easily installed by Householder


    Mains Powered, plug-in (with 2m lead)

    Easily installed by Householder


    Mains Powered, wired-in, interconnectable

    Electrician to install & rechargeable battery back-up.


    Mains Powered, wired in.

    Electrician to install.

    Note: The Ei261EN may be interconnected to the mains-power Smoke Alarm System.

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