Chch NZ build

[Lburou]

Re: Chch NZ build

Cut the bricks for the flue shoe and mortared them in place. Doing this in a howling Norwester ( a hot wind that blows of the southern alps across the Canterbury plain ) made it a bit tricky in terms of my balance and the homebrew drying out too quickly.
I allowed for a good expansion gap which i will fill with insulation / vermicrete when the flue is inserted. For once the tile saws circular blade was useful in helping to shape the necessary internal arcs.

The news reported an earthquake in Cristchurch, yesterday I think....Was it near you? I hope you are OK and that there is minimal negative affect on you and your neighbors

[brickie in oz]

Re: Chch NZ build

Brickie in Oz i note you have suggested charcoal as an alternative - how much is needed to get up to pizza temperatures?

I use the heat gun on timber too and it reduces the smoke to almost zero.

As for charcoal a couple of 5 kg bags gets the oven hot enough, at $15 per bag it can get expensive.

Try the heat gun on the timber first, set it to high and have the door slightly ajar, aim it at the base of the fire, the heat gun will melt over time.

Also had some major aftershocks today including a 4.9 - really scary!!

It must have been some fire ...

[John French]

Re: Chch NZ build

Tried to start a small wood fire but it was difficult to start and when it did catch is was very smokey. So much so the neighbours were out looking for the fire! So abandoned that venture. Used some charcoal brickets ( coconut shells source ) and a hot air gun to get a more acceptable heat source. Got upto to 80 C inside and after 6 hours the external dome temperature reached 38 C. A nice slow heat release which should be compatible with the curing process.
My really big concern is the smoke - there is no way i can produce anything like this mornings pollution in our urban situation. I really hope i have not constructed something i can never use!
Brickie in Oz i note you have suggested charcoal as an alternative - how much is needed to get up to pizza temperatures?

Also had some major aftershocks today including a 4.9 - really scary!!

[John French]

Re: Chch NZ build

Cleaned up the inside of the oven. Good to see the herringbone floor again although with the protective layer removed it was apparent that some mortar had slipped down behind the wooden framing securing the I tool. The mortar was really firm and took a fair bit of persuasion to remove.
Decided to start the heat curing process - used a gas burner to help control the temperatures. Took it up to 120 C max ( at the top of the dome ) and then let it cool down. The vent seemed to perform well with hot air being released from the chimney and not the front opening. Cooled down at about 1 deg C per minute.
Hopefully the new year will see an opportunity to use the oven in ernest!

[John French]

Re: Chch NZ build

Cut the bricks for the flue shoe and mortared them in place. Doing this in a howling Norwester ( a hot wind that blows of the southern alps across the Canterbury plain ) made it a bit tricky in terms of my balance and the homebrew drying out too quickly.
I allowed for a good expansion gap which i will fill with insulation / vermicrete when the flue is inserted. For once the tile saws circular blade was useful in helping to shape the necessary internal arcs.

[John French]

Re: Chch NZ build

Hi
Good luck with your project you will enjoy. I found that NZ is a more expensive place to build compared to US and Aus and these escalated as i worked through each stage. Hopefully the final working oven will prove worth this but i am not there yet! Certainly the time aspect is huge.
To answer your question i have used the 'homebrew' mixture throughout as outlined by previous posters - sand / portland cement / fireclay / hydrated lime in 3:1:1:1 ratio. It was easy to use especially once i got used to its consistency and application. I have not yet cured the oven by firing so i cant comment on it performance yet.

[Drewaudio]

Re: Chch NZ build

Hi John,

I've started an oven build in Hamilton, New Zealand but you're much more advanced than I am. It's good to find another kiwi working on a similar project so I can ask some questions! Did you use regular cement mortar for the arch or did you use refractory mortar?

Cheers!
Andrew

[brickie in oz]

Re: Chch NZ build

Wheres the pics?

[John French]

Re: Chch NZ build

Finished the brick vent today. After spending a long time thinking about the construction it is slightly disappointing to report that i would do it differently given the chance. However, although not perfect i think it will be adequate. I need to cut and fit brick to act as a shoe for the SS flue.
Does anyone know whether it is best to mortar the flue in or leave it 'loose' so it can expand freely?
If the latter how is it best to seal it?

Photos now added - be kind!

[John French]

Re: Chch NZ build

After a pause for thought I have resolved to fit a stainless steel flue. The availability of clay liners was nil, and to order a 10 inch one was not available for immediate delivery. Having seen some builds with the SS flue left exposed I am considdering that option. Although to build a brick chimney which will also reinforce the outer arch may become a necessity. The key for me was the ability to proceed with the vent installation asap - I was also able to get a good deal by buying direct from a flue fabricating factory.

[brickie in oz]

Re: Chch NZ build

and reinforce the vent walls to add more stability.

You sure will, gravity will win and push the arch towards the ground.
The arch will want to flatten out with gravity, its a fact.

[John French]

Re: Chch NZ build

I went ahead and built the outer arch. I may well end up having to build and extra decorative arch and reinforce the vent walls to add more stability. If i do this i will use bricks the same as our house to coordinate. The outer arch turned out okay although i am even more concerned as to its ability to stand up to the stress and strains of repeated heat cycles. I removed the form after about an hour and cleaned up the grout lines.
hopefully we have had our aftershock for the day having had a big one this morning!! About 3.2 on the Richter scale.

[Les]

Re: Chch NZ build

John,

I think the decision to add it came after I realized how much weight I was going to put on top of the entry way.

Les...

[John French]

Re: Chch NZ build

John,

I dropped some rebar into the hearth and then used cored bricks to "beef" everything up. I'm having no issues. I really don't know if it was needed but it seemed like the safe thing to do.

Les...

Just checked out your pictures - very useful. I think that will allow me to proceed and if i need to add the extra decorative arch / brick work. I do have room for it although it will take away the oven landing that i had earmarked for a counter.
At what stage did you decide to add the extra brickwork - or was it your intention from the off?

[John French]

Re: Chch NZ build

John,

I dropped some rebar into the hearth and then used cored bricks to "beef" everything up. I'm having no issues. I really don't know if it was needed but it seemed like the safe thing to do.

Les...

thanks for the info.
I thinkyour solution may be difficult for me unless i dismantle a significant number of bricks. I guess an option is to double up the vent walls or change my planned igloo for an enclosure with lateral support form the structure.
I am not intending to put any other load on the outer arch as i intend to support the vent on the side walls and inner arch / dome.
I am suprised there are not more threads reporting problems re outer arch.
Hopefully a few more builders are willing to share their knowledge and experience.