We recently replaced our aging back boiler in the living room with a new condensing boiler located in the garage. As part of the subsequent redecoration I want to brick up the old fireplace opening. There is a stainless steel liner in the flue at the moment with a terminal at the top.
Should I have the liner removed and the chimney sealed at the top, or leave it and put an air brick in when I brick up the opening? The latter would give some ventilation, which as the rest of the house is double glazed might be useful. If there's little to choose in practice then my preference would be the airbrick since I could do this myself. If the liner has to be removed I'll need to get someone in to do it.
Opinions and advice welcome please.
JC