Large vent blowing cold air

RelievedSheff

If you plan to get a gas fire fitted in that room then you will need ventilation.

Vents are there for a reason and should not just be blocked up.

grumbler

RelievedSheff said:

If you plan to get a gas fire fitted in that room then you will need ventilation.

Not with any fire

stragglebod

jagdipa said:

Just to be clear, I don't use the log fire, I never have used the log fire in the 2 years I have been in this house, and I was advised by someone with a hetas badge to never use it until it's checked (he said the chimney was not correct). 

I do plan to replace it with a gas fire, but that will not be for at least 5 years.
So I'm guessing it would be okay for me to block up the hole. I was thinking of using some polystyrene and foil at first, and then maybe brick it up next summer.

Do not block the vent without first removing the fire. I'm not sure why you're struggling to understand this.

It's not because blocking the vent would be 'against the rules'. It's because you could kill somebody.