Where the danger comes from
A gas flame needs oxygen. When a heater burns properly and its fumes go outside through a flue, it is safe. When it burns without enough air, or its fumes stay in the room, it produces carbon monoxide (CO), which stops the blood carrying oxygen.
The most dangerous set-up is a heater with no flue, or a blocked or disconnected one, inside a small bathroom with the door and window shut during a long, hot shower. Steam makes it worse by hiding the early signs. Gas leaks are a separate danger: natural gas has an added smell, so a smell of gas means a leak, not carbon monoxide.
Warning signs, and what to do
Early symptoms feel like flu or tiredness: headache, dizziness, nausea, weakness, drowsiness and confusion. If they ease when you leave the bathroom and return when you go back, treat it as carbon monoxide. Signs on the heater itself include a yellow or orange flame instead of a steady blue one, soot or brown marks around it, and a pilot light that keeps going out.
If you suspect it: turn the heater off, open the windows and door, get everyone into fresh air, and call an ambulance on 123 if anyone feels unwell or has collapsed. Do not use the heater again until it has been checked. If you smell gas, do not touch light switches, open the windows, close the gas valve if it is safe to reach, leave and call the gas emergency number, 129.
Prevention: the flue and the air supply
Every gas water heater needs a flue that carries its fumes outside, the right diameter for the heater, sloping and sealed at every joint, and ending in open air rather than a light well or under a balcony. A fan-assisted, room-sealed heater, which takes its air from outside and sends its fumes back out through a sealed duct, is the safest kind for an indoor space.
The room also needs a permanent air supply: ventilation openings that are never blocked, including in winter. The safest choice of all is to place gas heaters outside the bathroom, on a balcony, in a kitchen or utility area with good ventilation, or to replace them with electric heating or a central system, so there is no flame where people shower.
Alarms and servicing
A carbon monoxide alarm costs little and is the only way to detect the gas before symptoms start. Fit one near any room with a gas appliance, test it regularly and replace it when it reaches the end of its life. A smoke alarm does not detect carbon monoxide.
Have every gas heater and boiler serviced once a year by a qualified technician who checks the burner, the flue and the safety devices, and never let anyone remove a flue or cover a vent during renovation work. The same rules apply to gas boilers for central heating, which are normally room-sealed and fitted with flame and flue safety controls.
Make your hot water safe this winter
Check every gas heater in the house today: is there a flue, is it connected and does it lead outside, is the flame blue, and are the vents open? If the answer to any of these is no, stop using it until it is fixed.
Conversion EG has designed, installed and maintained hot water and heating systems in Egypt since 2010, with one team from design and supply through installation and maintenance. Book a site survey and we will check your heaters and flues, or plan a central or electric system that takes the flame out of the bathroom.
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