Cover for fireplace

[ujoni08]

I want to make a cover of sorts for the fireplace, to draft-proof the chimney when it's not in use. We have a Morso squirrel, with protrudes about an inch from the fireplace. There is a register plate with a flue, which I intend to seal up first. Any ideas for that? Heat-resistant silicon any good? Then, for the cover, I was thinking of making one out of wood. It would need to have some (short) sides, to allow for the protruding Morso, if that makes sense. SWMBO is going to object if I don't make it look good...

[Baz]

Not clear why you need to make a cover as normally a stove is sealed to the flue which is sealed to the rest of the chimney. Picture would help.

[ujoni08]

@baz, I think you're right. Once I've sealed the register plate and the flue properly, I probably won't need a cover. I'll give it a go...

[Baz]

Are you trying to improve the seal between the register plate and the flue in which case high temp silicone will do. I think it goes up to around 300C but check the label. |Between the plate and the stone of the chimney it shouldn't be that hot and a normal sealer may be ok but they don't jump a big gap so may need to build up cement (ordinary not fire cement) first.

[ujoni08]

Thanks for the replies.
At the moment there is a small gap around the flue where it goes through the register plate, and also some gaps around the register plate where it rests on angle iron around the perimeter of the chimney (which isn't perfectly rectangular). It's an unlined, uncapped, open stone chimney, by the way (1820s cottage). I have done a draft test as follows on a windy day, with all windows and doors tightly shut, and all vents blocked, I held an incense stick near the fireplace. there was quite a significant draft detected. At the moment, I have a thick fleece drape over it, and it gets sucked inwards and outwards when the wind blows.
I think that once I've sealed the flue with say fire cement or high-temp silicon, and then sealed the edges of the register plate in the chimney with say cement, it should be fine. I do shut the stove vents when not in use. I probably won't need a cover, but it would probably add to the thermal efficiency of the house, as the register plate is only a thin piece of some sort of fire resistant glass-based board...

[Ivan]

Yes, sealing all the gaps you mentioned should do the trick. The morso is a single-door stove, and seals well - but check the door seals are in good condition. With double-door stoves, you find that the seal between the two doors fails fairly quickly, and so it is very difficult to get twin door stoves to seal well in practice.

The other hole that might need sealing is the hole where the external riddler exits the stove. I can't remember exactly what it's like on the Morso, but a few magnets and a large close-fitting washer would probably sort it out.

[ujoni08]

Thanks, Ivan. Yes, I replaced the rope seals about two years ago, and they still seem to be fine. The riddler goes through a hole with a small gap around it. I'm going to see if I can find a suitable washer to seal it up.