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Gas fireplace - regulation regarding ventilation

Hello, I recently bought a flat with a gas fireplace which is supposed to be working. I called a Gas Safe engineer to confirm it and show me how to use it and he said it is not in line with regulations and to do so I would need 1) to do a big whole in my wall and put a ventilation grid, so that there is permanently air coming into the flat and 2) fix the plate the closes the liner permanently so that it is always open ( right now I can move it so it closes/opens the liner).
I am really surprised: why would I need to permanently keep the liner open and not just when I use the fireplace? And why would I have to get a massive hole in my wall all year round? I don't want any cold air to come in in winter!
I am confused. May thanks in advance for your advices!

Can I just replace the gas system? I quite light the fireplace like this. If yes, what other gas system would not require me getting a big hole in my wall?
Many thanks again this is really usefull (although I still don't understand why this ventilation must be maintained all year round and not just when we actually use the fireplace!).

5 Answers from MyBuilder Gas Engineers

Best Answer

Hello If your gas fire is what we call a" Decorative",basket effect gas fire then automatically gas regulations state a 100mm ventilation hole through the wall directly to outside air.If the fire is classed as an "inset" or surface mounted gas fire and as soon as it is rated over 7killowatts of power then you will also need ventilation direct to outside.The reason for this is that potentially if it was a cold winters night and you had a gas fire on in a room . If you closed all windows and doors to the room and you had two to three people in the room ,then your bodies as well as the gas fire would use the oxygen up quickly. .This would starve the fire of oxygen for a healthy flame.79 % of air is nitrogen and only 21 % is oxygen.Nitrogen is no good to you or the fire so you are potentially relying on only the 21% oxygen.So,to your next question about the "flue damper "the bit of metal that closes off the flue above the fire .Imagine that two to three people are asleep in the room and all windows and doors to the room are closed.Nice and snug. All of a sudden there is down draught in the chimneys flue,the wind blows closed that flue damper. Now there is no way of the fires combustion to leave the room .The fire and your bodies are starved of oxygen after a short period of time. Now the flame will form CARBON MONOXIDE POISONING.You`ll be dead within half an hour. Carbon monoxide poisoning affects people in different ways. Flue like symptons . Tiredness. Fatigue are the most common to begin with before symptons get worse. Two reasons for Carbon Monide poisoning. Lack of oxygen or " flame inpingement"anything that interferes with the flame.Trust your Gas Safe engineers judgement.Your installation is classed as " AT RISK".Visit and view the videos of real life people who have lost loved ones through Carbon Monoxide poisoning.Oh,and one last thing.BUY YOURSELF A CARBON MONOXIDE DETECTOR FROM B&Q , SCREWFIX. TOOLSTATION OR ANY OTHER STOCKISTS.CARBON MONOXIDE IS COLOURLESS AND ODOURLESS.IT COULD SAVE YOUR LIVES.COST AROUND £15.00.Good Luck.


Answered 4th May 2019

I assume you have an open flued fire. regulations state you need perminant ventilation to prevent the products of combustion coming back into the room.

Your gas engineer is correct in what he said.

I suggest you consider replacing the old fire


Answered 31st Jul 2011

the advice he gave you is spot on


Answered 31st Jul 2011

They do, see link below:


Answered 22nd Aug 2016

If the gas fire is under 7KW you don't need ventilation for it unless it's LFE gas fire or a flueless gas fire.


Answered 14th Nov 2020

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