An unused chimney that howls is usually the balloon
I sat in the front room in January and the fireplace howled. A low, hollow note when the wind crossed the pot. The fire had not been lit in years. I put a hand in the opening. Cold air came down in a column. I thought the room needed another radiator. It needed the unused flue shutting. I put a chimney balloon in, inflated it until it sat, left the string where I could reach it, and the howl stopped. The chimney was still there. The hole was not open.
A chimney balloon is a bag you inflate in an unused flue so the wind cannot fall down it. A cap on the pot does the same job from above. Either is hardware for a flue you do not use. I will not tell anyone to block a working flue. If you burn anything in that opening, this note is not for that chimney. Take the balloon out before you ever light it. A blocked working flue is a different kind of danger and I am not writing that job.
A loft hatch that dumps heat is usually the catch is the hole in the ceiling. A letterbox that howls is usually the brush is the slot in the door. An unused chimney is a bigger slot. The balloon is the catch.
When I check I make sure the flue is unused. No ash, no recent heat, no one in the house who still lights it. I look up with a torch if I can. I measure the opening so the bag I buy can sit, not rattle. I inflate until it is firm on the walls and I keep the string in the room. A balloon you cannot retrieve is a lump you will regret. I do not stuff the throat with newspaper and bin bags. That is not a balloon. It falls, it rots, and you will fish it out in April.
A cap is the other hardware if I can get to the pot safely, or if someone who can is already up there. I do not climb a wet roof for a howl. I do the balloon from the room.
Skip a new fire because the old one sang. Skip sealing an unused flue with mortar as a Saturday job if you do not know the stack. Skip a balloon in a flue you might light this winter. Skip inflating until the bag creaks. Firm, not a burst. Skip forgetting the string behind a board. I tape a note on the mantel. Unused. Balloon in. String here.
I am not writing a sweep catalogue. If the unused flue is full of debris, I stop and I do not shove a bag up a blockage. If I can see daylight and the flue is clear and unused, the balloon is the job.
UK year is the first hard wind after the heating is on. I now stand in that room and I listen. If the fireplace notes, I check it is unused, then I shut it with a bag I can pull out. I do not buy a stove to stop a draught.
The room will still need a bit of air from somewhere else. I am shutting one howl, not sealing a house. If a room goes stale, I have overdone the holes I closed. I open a window I can control.
I do not need a new fireplace because the unused chimney howled. I need a balloon or a cap on a flue I do not light, and a string I can find.
If I later add a buy link here, it will be a paid promo.