Fire going out dependent on weather, room pressure?

[slim reaper]

Whats the horizontal distance from the flue to window wall.

Your cowl it a terrible style and could cause problems

[Pacemaker1000]

16 minutes ago, slim reaper said:

Whats the horizontal distance from the flue to window wall.

Your cowl it a terrible style and could cause problems

3.5m

[Pacemaker1000]

1 hour ago, GarethM said:

Omit the no, it would prove your not getting enough fresh air to the fire.

 

I don't care how big the room or house is, if you open a window and the fire roars.

 

Then the fireplace isn't getting enough air to operate via the room sealed air supply vent.

If there was a lack of oxygen wouldn’t it die out gradually not stop immediately?

[Steven P]

How new is the extension? I could look back but did you say how big the stove is? My old house is quite leaky - draughts everywhere, but a modern extension I think would be pretty much sealed, not so many draughts. A 5kw Stove is generally OK for the amount of air available from draughts - you know that though.

 

Does this happen more are high pressure outside or low pressure (I am guessing at higher pressures?)

 

So looking at your description, smoke comes down the chimney (or doesn't rise) and out into the room - suggests to me that this is the easiest path for the smoke to take - higher pressure at the cowl than in the room? Might sound odd but if the room is well sealed, could the air from the room going up create a lower pressure in the room and eventually that is enough to get a backdraft? Opening the window a bit, the pressure equalises and then back to hot air rises. Air flow from duct won't affect this - maybe your extension is too well insulated? Try cracking the window open a touch when the fire is going. Would be worse if it was high pressure outside I think

 

Just off the top of my head from your description

 

I'd also look to houses all around here, the chimney is generally higher than the rest of the house

[GarethM]

As per Steven P, it's not just oxygen for the fire to burn it needs to draw sufficient air up and out of the chimney.

 

Opening that window proves your home is too air tight and the vent for the fireplace is probably blocked or is at the very least insufficient.

 

Is it a room sealed vent or are you just taking air from the room, either way do not use it until it's sorted.

[Pacemaker1000]

Yes the extension is well sealed. Doesn’t have any opening windows just opening velux roof ones. room is open into two other rooms

i doubt opening the roof vent would suddenly allow more oxygen to reach fire especially as it happens when room vent was blocked off and only using external vent?

but it would allow for pressure balance I expect.

had much success tonight with roof vent only cracked open

 

so what creates pressure difference and will a new cowl help?

 

thanks

[GarethM]

A cowl will do nothing unless you can get air into the room. Opening a window is an automatic fail for any stove installation because people can close them.

 

Not enough air = Carbon monoxide 

Edited November 26, 2022 by GarethM

[Pacemaker1000]

30 minutes ago, GarethM said:

A cowl will do nothing unless you can get air into the room. Opening a window is an automatic fail for any stove installation because people can close them.

 

Not enough air = Carbon monoxide 

CO2 alarm never gone off.

Could opening a window 4m from stove by just an inch let enough extra oxygen to quickly restart the stove which is setup to draw external air??

[GarethM]

Stop using the word oxygen, it's not just oxygen but actual air flow.

 

Yes, opening a windows provides enough air flow to get it burning but that is not a permanent solution as windows can be closed.

 

You need to see if you can fit a room sealed kit for the fireplace, as they cannot be closed even accidentally.

 

I suspect you don't have an installation certificate, as this would also identify the air supply location and sizing.

[Pacemaker1000]

58 minutes ago, GarethM said:

Stop using the word oxygen, it's not just oxygen but actual air flow.

 

Yes, opening a windows provides enough air flow to get it burning but that is not a permanent solution as windows can be closed.

 

You need to see if you can fit a room sealed kit for the fireplace, as they cannot be closed even accidentally.

 

I suspect you don't have an installation certificate, as this would also identify the air supply location and sizing.

It was installed by previous owners so no certificate 

there is a room seal kit fitted but on examination there are small gaps but 99% air comes from outside.

only happens on windy days

Edited November 26, 2022 by Pacemaker1000