Parts list, please comment

[RichC]

Got a parts list from my local refractory for kit oven. I specified a 125mm vermicrete base that 1.2 x 1.4 metres in size and to cover the dome in 2 layers of fibre blanket + 200mm layer of vermicrete.
Prices in €. Obviously I'd like to save money where possible, can anyone tell me if there's any cheaper alernatives or changes I could make to this without impacting oven performance?
1 x Pizza dome 200.00
1 x pizza circular base 120.00
1 x base front brick 10.00
3 x arch bricks shape 60.00
2 x 6" flue liners 20.00
20 x 50 bags of vermiculite @ 11.50 each 230.00
10 x rapid set cement @ 8.50 each 85.00
2 x rolls Fibre blanket @ 60 120.00
1 x din -set 14 @ 45

Thanks

Richard

[cobblerdave]

Re: Parts list, please comment

Gudday
That seems a lot of vermiculite ? I don't now how big the bags but just check the price it's nearly 3 times the price of the ceramic blanket. Vermiculite is usually cheaper than ceramic for insulation
Regards dave

[david s]

Re: Parts list, please comment

You don't specify the thickness of the two layers of CF blanket, but to back that up with 200 mm vermicrete sounds excessive. The stuff is also tricky and time consuming to place and takes ages to dry. If you plan on making a 200mm layer of it you'll be cursing your plan.

[brickie in oz]

Re: Parts list, please comment

Whats a din set?

[RichC]

Re: Parts list, please comment

CobblerDave, they're 50L bags if vermiculite.
Davids the cf blanket is 25mm.
Brickie, the dinset is the stuff used to seal the joints on the done and hearth and blobs of it are used to stick on the fibre blanket, it looks like refractory mortar to me.
So guys, should I just go for double layer of blanket and 100mm vermicrete?
I intend rendering the whole structure to make it weatherproof eventually.
Thanks for your inputs

Richard

[RichC]

Re: Parts list, please comment

I did some calculationsand my heart insulation is 1.6 X 1.2 X 0.125metres(5 inch slab)= 0.24metres.
The dome is about 1metre diameter, so allowing for about 225mm of insulation thats 0.22 metres.
Will call it 0.5metres total so thats 10 X 50Litre bags
25Kgs cement fondu per 100litres vermiculite gives 6:1 mix so 5 bags should allow me to get 5:1 mix in base and 10:1 in dome, so I need.....
500L vermiculite and 5 bags cement fondu
Am I calculating right?

Thanks

Richard

[david s]

Re: Parts list, please comment

Ciment fondu is a waste of money to make vermicrete IMO because it doesn't get hot enough to warrant it. It also goes off much faster than portland and that can lead to wastage. Portland cement is a better option unless you are getting the Ciment Fondu at a really good price.
When you listed rapid set cement in your ingredients list did you mean Ciment Fondu?
In our country Rapid Set is a dry concrete blend containing sand and heavy aggregates that you add water to not just the cement component. If you price Ciment Fondu (calcium aluminate cement) i think you will find it quite expensive.

[RichC]

Re: Parts list, please comment

Ciment fondu is a waste of money to make vermicrete IMO because it doesn't get hot enough to warrant it. It also goes off much faster than portland and that can lead to wastage. Portland cement is a better option unless you are getting the Ciment Fondu at a really good price.
When you listed rapid set cement in your ingredients list did you mean Ciment Fondu?
In our country Rapid Set is a dry concrete blend containing sand and heavy aggregates that you add water to not just the cement component. If you price Ciment Fondu (calcium aluminate cement) i think you will find it quite expensive.

Thanks David, thats just the sort of pointers im looking for. As far as I can figure the rapid set cement is cement fondu from my local refractory. It costs 8.50Euros per 25kg bag and I have to drive a 3 hour round trip to get it with a trailor(along with the other parts). I can buy portland cement in my local hardware for 5Euros per bag so thats that decided!
Whats the intended advantage when using cement fondu? I've never heard of it before. I just assumed it had better insulating properties as it was for the vermicrete? Since the bottom of my hearth slab sits on the vermicrete(and the dome also), I assume this means that the vermicrete will be exposed to oven temperatures when at full heat?

Thanks

Richard

[david s]

Re: Parts list, please comment

Ciment Fondu is calcium aluminate cement and is good for really high temperatures. Portland cement is calcium silicate and doesn't like temperatures exceeding 300 C. Because the vermicrete contains tons of air only the very surface of it which is in contact with the floor bricks would be subject to this kind of heat. Anyway in practice Portland cement has proved perfectly adequate for the vermicrete in the under floor insulation slab. Like I previously posted if you can get the stuff cheap (I can't) then you could use it, but it's overkill really.

[RichC]

Re: Parts list, please comment

Ciment Fondu is calcium aluminate cement and is good for really high temperatures. Portland cement is calcium silicate and doesn't like temperatures exceeding 300 C. Because the vermicrete contains tons of air only the very surface of it which is in contact with the floor bricks would be subject to this kind of heat. Anyway in practice Portland cement has proved perfectly adequate for the vermicrete in the under floor insulation slab. Like I previously posted if you can get the stuff cheap (I can't) then you could use it, but it's overkill really.

Would it be a better choice for around the chimney flue or would that be unnecessary also?

[david s]

Re: Parts list, please comment

The home brew is quite adequate IMO. You will presumably have blanket around the bricks at base of chimney. Mine never gets that hot anyway the inside of my flue gallery never goes white.