Fitting extract grille or cowl for lpg cooker vent

[TryAgain1]

Swinging flap only opens with a fan I though.
No fan pushing it open then it will remain shut

I fit this https://ebay.io/m/7vF0aB over the airbrick

 

[TryAgain1]

I dont think you need to worry too much about LPG getting stuck in a higher level vent

So this cowl hood (https://ebay.io/m/7vF0aB) can be installed over the airbrick in the kitchen in which the gas appliance has its own separate vent

 

[TryAgain1]

That's not extracting. I guess you know that reading your post...
That will let oxygen in when you burn gas.
Look up air vent with insect mesh.
Not my area but I've just seen vents in kitchen and that was good enough according to fitters.
Also trickle vents on windows.
Maybe this will help.

You are right it's not extracting it's passive vent to prevent CO buildup. The gas cooker has its own separate vent (with fan)

 

[Razor900]

If the kitchen is less than 10 cubic metres it does need ventilation. An extractor fan is usually not suitable.

https://www.screwfix.com/p/manthorpe-core-vent-brown-160-5mm-x-350mm/37873 will work fine and meets requirements with the internal baffle left in.

The gas you have is heavier than air so even if it was a thing it couldn't get stuck in the vent

 

[TryAgain1]

If the kitchen is less than 10 cubic metres it does need ventilation. An extractor fan is usually not suitable.

https://www.screwfix.com/p/manthorpe-core-vent-brown-160-5mm-x-350mm/37873 will work fine and meets requirements with the internal baffle left in.

The gas you have is heavier than air so even if it was a thing it couldn't get stuck in the vent

The kitchen is more than 10m3. Is natural gas or CO heavier than air? Though the gas cooker has its own extract vent

 

[Razor900]

You said it was 5-10 earlier. Over 10 you just need an openable window

You also said LPG gas?

 

[TryAgain1]

You said it was 5-10 earlier. Over 10 you just need an openable window

You also said LPG gas?

The original kitchen was about 9m3 conservatively. Now the kitchen plus back room (partition wall removed) is at least 15m3. The cooker is fed using LPG had from bottles

 

[TryAgain1]

You said it was 5-10 earlier. Over 10 you just need an openable window

You also said LPG gas?

LPG is about 1.5 times heavier than air according to google so , in worst case scenario, leaking LPG gas floating through the air vent out air brick should sink down to ground so the vent cowl (fitted over Airbrick) should not cause LPG gas to build up inside the cowl

 

[Razor900]

LPG is about 1.5 times heavier than air according to google so , in worst case scenario, leaking LPG gas floating through the air vent out air brick should sink down to ground so the vent cowl (fitted over Airbrick) should not cause LPG gas to build up inside the cowl

Yes, that's what I have been saying. If the gas builds up enough to reach a high level vent you really do have problems!

In any case an openable window is all you need

 

[dilalio]

LPG is about 1.5 times heavier than air according to Google physics

Fixed that for you!