Attaching Flue

[Behen]

We have finished our vent and are about to attach the flue. I have read that you should only use a small amount of morter to attach it. How much is sufficent? Just a small smear of morter up the side of the flue and down on the firebrick it's resting on an inch or two up? Also we are planning on making a brick chimney around the flue. I saw there should be a gap between the brick and the flue. How big a gap? Is there any reason we shouldn't use regular brick for the chimney? I've attached photos. Any help would be appriciated. Thanks

[cobblerdave]

Re: Attaching Flue

Gudday
Normal bricks are more than enough and lighter as well . I would leave a space around the ceramic flue to take into account Expantion. You could even put some insulation between the flue and brick if you like
I really do admire your arch that is very good work . I think you should post it at the top of the forum page for all to admire!
Regards dave

[Behen]

Re: Attaching Flue

Dave,
Thanks so much for the reply and kind complement! Sorry not to have replied sooner. Here's a photo of what it looks like now. All we're waiting on is a delivery of the ceramic blanket. Once we get the dome insullated we'll stucco it over and start the curing process! I can't wait to get the oven fired up! Thanks again!

[deejayoh]

Re: Attaching Flue

Nice looking oven! You can (and probably should) start curing before you put on the insulation and stucco.

[Behen]

Re: Attaching Flue

deejayoh,
Thanks for the kind complement. We're stating to cure it today (pre insulation and stucco), can't wait to get it all ready for a big fire...hopefully in a week or so.

[GIANLUCA]

Re: Attaching Flue

looks good!

Definitely start curing now I'm on my 5th fire and still completing

[Niro]

Re: Attaching Flue

Nice looking oven! You can (and probably should) start curing before you put on the insulation and stucco.

could anyone please explain why the curing take place before the insulation, and what will be the effect if i start curing after i put installation and plaster

[david s]

Re: Attaching Flue

could anyone please explain why the curing take place before the insulation, and what will be the effect if i start curing after i put installation and plaster

There are two schools of thought about this and pros and cons for each method. If driving off the water before insulation it can escape more easily. The downside is that it results in a far greater temp difference between the inside surface and the outside surface of the bricks or refractory. This leads to a greater difference in expansion which means stress. If you intend on adding vermicrete over the oven then you are adding a large amount of water after just having dried it out, so that water
also needs to be removed before a render coat is applied. It all depends on how you plan to build the oven. Some builders have neither wet vermicrete or wet render on their ovens. The way I build ovens is blanket over the dome, then a layer of vermicrete, to even out the bumps and leave you with a nice firm substate to render against, a week of drying in the sun (hope there is some) the drying fires, then a cement render coat.
Which ever way you do it just make sure you dry it out slowly.

[Niro]

Re: Attaching Flue

Thanks David..
I currently finished applying the insulation (blanket) and the first layer of a cement coat (there will be a second layer coat).
i wonder if to start curing now or after the second render coat?
and what was your method to maintain 300F and so on in the curing process
please advice

[david s]

Re: Attaching Flue

Thanks David..
I currently finished applying the insulation (blanket) and the first layer of a cement coat (there will be a second layer coat).
i wonder if to start curing now or after the second render coat?
and what was your method to maintain 300F and so on in the curing process
please advice

I like to retain the moisture in the outer rendered shell by wrapping it in cling wrap for a week to enhance its strength.Maybe you could do this for the final coat. Also rubbing a sponge over it when finished will produce a nice even finish.
Regarding the method for maintaining an even, low temperature, I use a method that we are not allowed to discuss (see curing thread). You can use heat beads/barbecue fuel to achieve a slow even burn also. Try to avoid too much direct flame impingement on the dome.