Wood fired heater & vermiculite clay bricks

[mickmac42]

I'm going to throw this one out to the masses because i'm out of my depth. I recently had my wood fired heater cleaned and the guy sold me on installing some vermiculite clay bricks. He said they'd help protect the cast iron body as well as retain heat for longer. I've seen a number of newer heaters are lined with clay bricks and figured it the refit would be worthwhile. Old mate installed the bricks by sticking them to the cast iron walls with a silicone based glue designed for high temperature applications. I don't know what it was, but it hasn't lasted. About three weeks after they were installed, all ten bricks have come away from the wall.

In the past i'd have chased him up and got him back around to fix his work. I'm getting tired of having to do this with so many contractors, and would rather just do it myself. That said, i've got no idea what product to use. Has anyone done this themselves, or have any knowledge to share? I've done a Google search and learned about adhesives for fireplaces. Does anyone have any experience, tips & tricks to share with this sort of thing?

Mike

[dales133]

Sika make a high temp fire resistant polyurethane adhesive.
It's avaliable at most places that sell sika products.
I can't say I've used it but I've used plenty of thier gear over the years and it's not cheap but it does what it says it does, in fact it's the industry standard for all its competitors

[steppenwolf]

I read all about the Vermiculites in the Old Testament. "Yea, and Joshua did smite the living crap out of them."

[KeithB]

In a previous life I used to be furnace engineer for one of the big aluminium companies.
I can't see any kind of chemical adhesive lasting more than few hours and I'd look to what they do in furnaces, where bricks are bedded in with a suitable refractory mortar. You can go to an industrial supplier or use Fondu Cement or look at this Selleys stuff from Bunnings, which looks like it might do the business.
http://www.bunnings.com.au/cement-rtu-selleys-850g-fireproof_p1210135
Keith

[stropp]

Go into a wood heater shop and get silicone based fire cement, that will do the trick no worries.

[Suncruise]

I have got those bricks in mine and they are just held in place by a piece of angle iron that sits on top running the three sides of the fire box.

[Ozsnowman]

I have got those bricks in mine and they are just held in place by a piece of angle iron that sits on top running the three sides of the fire box.

+1
Yeah, mum has had a few fires over the years, and he bricks always sat in an iron channel.

[mickmac42]

I ended up calling the guy and talking to him about it and he came out to have a look. He admitted they were having problems with a batch of their sealant and offered to refund the money for the bricks. He did say that the bricks aren't usually held in place by sealant, but rather slot into place (like the angle iron bracket). That's not an option on mine, so he had another crack with another type of sealant. I can't remember what brand it was, but i saw it was rated to 800 degrees. Unfortunately it still wasn't enough. Within a couple of days the fire had cooked the sealant and turned it to dust. I figure i'll just leave it be. Thanks for the help, guys.

Mike

[dales133]

Yea that selleys stuff or the fireproof  sikaflex should work

[CC2005]

For what it is worth, I'd try contact several boiler manufacturers. 

One company that I had an association with used to use cement bricks, and a vermiculite type of product to render the domed and cylindrical internals of fire tube boilers.  Not my area of expertise.

Aira Pty Ltd  (Vic)  [Boiler & Pressure Vessel manufacturer]
Head Office - Victoria
144 Colchester Rd
Kilsyth, VIC 3137
Tel:  61 3 9839 8000

Hunt Boilers (Vic)  [Boiler & Pressure Vessel manufacturer]
Hot Water System Supplier
Address: 11 Helen Kob Dr,
Braeside VIC 3195
Phone:(03) 9580 9377

Tomlinson Boilers  [Boiler & Pressure Vessel manufacturer]
u16/45 Normanby Rd,
Notting Hill VIC 3168
(03) 9541 8600

[kylarama]

Forget fire rated sealants/mastic. It's fire rating is basically for 1 use. I use tonnes of this stuff at work for fire rated walls like comm's rooms and secure vaults. Its designed to withstand intense heat for only a few hours, after that it's shot.

Allot of the fire rated cements are no good either. They either have no adhesive properties or set hard. Metal expands and contracts very differently to hard cement, so will eventually break free.
The silicon based cement (I assume flexible) someone mentioned earlier would last the longest.

Could you get some say 30x3mm flat bar bent up in a U shape to the internal size of the wood heater with the bricks fitted. Wedge it in around the 3 walls to hold the bricks up?

Sent from my GT-I9507 using Tapatalk

[mickmac42]

I had been thinking of something similar, though using three pieces of angle bar welded into a U, so they brace against themselves. I really just want to keep the bricks from falling into the fire if they get nudged by a log.

Mike