Air bricks

[Andy M]

Hi everyone, 

Im currently in the stage of ripping up my carpet and replacing with wood flooring, 

In doing so I found a vent in my floor under one of the cupboards. The house is built on rafts I believe, is has air bricks on the front and the back of the house both located just off ground level. I understand that you cannot block the air bricks up due to obvious reasons of rot and damp. My question is, is this hole due to an old heating system maybe ? It gives off a massive draft you can actually feel the cold air being pumped into the house (not ideal in the winter with these heating costs!). Am I okay to block it up as the air bricks at the front of the house are still venting under the floorboards surely ? I’d be much appreciative of any help and advice. Thanks 

(picture attached) 

[Conor]

That'll be reminants of an old warm air heating system.

[Andehh]

Yep, warm air. I had them in the ceilings in a previous house, but floor ones also an option. 

[Andy M]

Okay great thanks guys. So I’m okay to go ahead and block that bloody black hole up 🥶