Insulating an unused fireplace

[Happyhomeowner]

On this site I found this advice: "If the fireplace is never used, it may be advisable to cover it and seal off completely. It is necessary to fit a 'hit and miss' ventilator to provide ventilation for the flue." Why should the room require ventilation through the flue? No other room has such ventilation. If there is no combustion occurring in the room and the room is heated by the furnace through ductwork (like the rest of the house), why the need for ventilation through the chimney? And what is a "Hit and Miss ventilator"?

 

[xerxes]

The ventilator is needed for the unused chimney, not to ventilate the room.

A hit-and-miss ventilator has a sliding plate which allows you to close it if you want to for any reason. There's no need to fit this particular type.

 

[Happyhomeowner]

Hello Xerxes, thank you for your reply. I don't understand why an unused chimney needs to be ventilated.

The fireplace is fitted with a damper, which sounds similar to the hit and miss. It's just not an effective barrier both because it's metal and because its doesn't close with a good seal.

How about if I take a piece of rigid insulation and cut it to fit snugly just below the damper?

I'm planning on putting a gas fireplace insert into this fireplace some day, so I don't want to invest too much in this project, or do anything that is difficult to reverse.