Could I use two split firebricks instead of one full firebrick?

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xprs

New Member
May 27, 2023
3
NL
So two 9" X 4.5" X 2.5" firebricks instead of one 9" X 4.5" X 1.25"? Nowhere local seems to carry the full bricks, and to get them shipped here would cost a lot. This is for a Newmac furnace if it's relevant to know.
 
I'd think that thermally that's fine. But mechanically they'll break more easily.

And I don't know how this would affect the safety certification?
 
I'd think that thermally that's fine. But mechanically they'll break more easily.

And I don't know how this would affect the safety certification?
They're the bricks on the side so they shouldn't be exposed to much impact damage, and if it doesn't work out then I'll just bite the bullet and order online and have a full size shipped in, main concern is for the thermal aspects, whether having two together would somehow affect the insulating quality. Not sure about safety certification, this furnace came with this house when I moved in.
 
Thermally the additional interface will be good. If they bricks are tight and no airflow goes between them.

Sides can get busted, so do be careful.
 
two 9" X 4.5" X 2.5" firebricks instead of one 9" X 4.5" X 1.25"
"Glue" them together with furnace cement...I've done this on broken bricks many times, it works great.
Wet the surface first, apply the cement evenly, a lil on both sides, put them together, then set them aside for 24 hours to dry before firing up...another brick or two on top while they cure would be good too.
 
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"Glue" them together with furnace cement...I've done this on broken bricks many times, it works great.
Wet the surface first, apply the cement evenly, a lil on both sides, put them together, then set them aside for 24 hours to dry before firing up...another brick or two on top while they cure would be good too.
Oh nice thanks, I didn't realise they had such a thing, that could definitely work, in fact the crack in the original brick itself could probably just be sealed using that, I haven't removed it yet to look closely but it looks like a fairly clean break.
 
in fact the crack in the original brick itself could probably just be sealed using that, I haven't removed it yet to look closely but it looks like a fairly clean break.
Absolutely...I've glued some pretty busted up ones back together that I didn't think would hold, but were fine...never had one break at the same spot again
 
All firebricks are not the same, there are different densities and you probably won't find the more durable high density bricks on any store shelf, wood stoves don't use them. I think there is also a temp. rating that differentiates the bricks. If you can find a manual online or contact the company directly they can probably tell you which bricks need to be used.