I have an open fireplace that has had a new wood heater put in similar to pixel. What would be the best material to block the open chimney and stop all my heat going out the top and how should I do it? Thanks

I've done quite a few similar projects as part of my job.

The easy way is to cut sheets of mineral wool (i.e. one of the stiffer Rockwool variants) to fit around the new stove pipe. The sheets should be slightly oversize so they will stay in place on friction alone once pushed into place. Ideally use two layers and make sure the joints in the second layer are in a different place than imin your first layer (helps make it more airtight).

A more involved way is to use Skamolex/Vermiculite sheets or even thicker fireproof calcium silicate sheets cut to size. Use temporary supports to hold the sheet in place, and fashion a concrete lip around the underside of all 4 edges for it to rest on.

Sheet metal will also work, but requires more/better electric tools.

A calcium silicate sheet can be cut with a hand saw whereas metal requires angle grinders or special blades.

Always wear a mask when sawing calcium silicate, the dust carries a risk of silicosis on your lungs with prolonged exposure.

>>2927996
Thanks! Would the rockwool do a better job of keeping the heat in than a silicate sheet or sheet metal? Or would you use both? I imagine it would be quite difficult to get the sheet to seal around the flue

i do not think i understand if you stop the combusted material from escaping you will suffocate from the extra carbon dioxide/monoxide

>>2928030
Me again. Glad to be of help. I take it your setup is a metal flue/chimney pipe in an existing brick or ceramic pipe.

Is the metal chimney isolated? There are typically 3 types of steel chimneys: un-insulated, 25 mm insulation or 50 mm insulation. The insulated ones will have a center stainless steel pipe surrounded by 25/50 mm insulation and an outer metal pipe (typically painted black).

If yours is an isolated one, you can use an epdm rubber surround around the steel chimney to get a 100% seal i combination with vermiculite, silicate sheet or metal.

What country are you in if you don't mind me asking? Helps to know what's available in your region.

>>2928142
Yes it’s an existing brick fireplace. Im in Australia .The house itself is about 70 years old and it has a nectre heater fitted where the open fire used to be and it has the black pipe but I’m not sure about insulation on it. It does get very hot still that’s why I’m cautious to put anything too close to it

>>2927986 (OP)
they make a double wall thimble thats suitable for direct wood contact. like the other anon said theres lots of mineralwool insulation rated for thousands of degrees you just need to wrap the pipe and frame the bottom of the opening closed. id probably use piece of cement board cut to fit up in the chimney around the pipe to stop the cold draft

>>2928227
fuckin (1/2)chan punishing us phonefaggots with sideways picels

>>2928220
If you're in Australia why the fuck do you need a woodstove

>>2928269
Cause it’s bloody cold mate
>>2928227
I think this is what I’ll do

>>2928269
Negative temperatures do exist in Ausfail believe it or not. And we don't have central heating, double glazed windows or really any standards for insulation or energy efficiency to speak of. Most houses older than 20 years have barely any insulation at all. Breathing white air indoors is not uncommon in winter.

>>2928269
must be in the south

>>2928291
what there's no electricity in the outback?

You guys are insulating the pipe that takes the hot exhaust out of the house? Isn't that backwards? Don't you want that to radiate its heat back into the structure?

>>2928747
i guess the problem is that is inside a brick chimney so it doesnt really help

>>2927986 (OP)
anon you want a heat exchanger like picrel to get the heat before it goes up

>>2928747
if you cool the smoke too much it wont draw well and the chimney will plug up in a hurry
>>2928781
>heat exchanger like picrel
those are a meme that clog up
t. had a magic heat and threw it in the scrap bin

>>2928802
>if you cool the smoke too much it wont draw well and the chimney will plug up in a hurry

Basically this, an uninsulated chimney means that you lose more heat to the chimney which can lead to tar condensation problems, by insulating the chimney it's actually possible to extract more heat from the fire. The rocket stove guys have some interesting work on this see Peter van den Berg's reports.

>>2928228
I think it's because they remove the exif