smoke coming out top of dome

[Behen]

We built our oven up to the vent & chimney in 2010 and for a variety of reasons didn't get to finish it until this summer. Consequently the dome had a long time to sit. It was covered with a layer of waterproof reftractory cement the entire time. We are finally starting to cure it and this morning as we lit the fire we noticed a small crack in the top of the dome with whisps of smoke coming through (the fire got up to 500 at the top of the dome for short periods last night, we found it very hard to keep the temp low). We also have a unique dome top, it isn't perfectly round. It has a kind of a point in it. I've attached photos of the dome and the crack. Can't see up into the dome its self at this time as its pretty black in the and hot at the moment. My questions are: 1) should we repair the crack and if so how; and 2) does anyone think the point in the dome will be an issue and if so would we have to grunge around inside the dome and fill it in? We're praying that will not be necessary.

[Bookemdanno]

Re: smoke coming out top of dome

Its a bit hard to tell, but after that long a lay off, you could be seeing steam rather than smoke as the moisture within the brickwork gets driven off.
Get some more fires into it, but keep the first couple at 300 or so, then build up from there. Once you've dried it out properly, then repair any "damage", insulate and get it stucco'd.

[deejayoh]

Re: smoke coming out top of dome

I thought that it might be steam too - but given the color of the stain in the second picture, it seems pretty clear that it is smoke - so there's probably a void in the brickwork somewhere letting it out.

Repair would be need to be done from the outside. Mortar applied to the inside of the dome is not going to hold.

If you are sure it is smoke getting out, and not steam - I would chip away the refractory around the leak, see what's up with the brickwork. You could probably remove some of the mortar with a grinder, and then repoint the problem area. I would not try to just cram more mortar into the existing gap, as I don't think you'd get a good seal.

The pointed top is less than ideal from a performance standpoint - but I don't see why you'd need to tear it down. Seems like you can fix this pretty easily with a little elbow grease and some cheap materials.

Can you turn those pictures before posting next time?

[Behen]

Re: smoke coming out top of dome

Thanks all for the help. I think we'll fire it slowly @ 300 for a couple days & monitor the smoke/steam. We'll also try to get a better look on the inside when it cools down to see if there are any cracks in there. If we determine its smoke & there's a crack we'll grind out the hole on the ouside of the dome a bit and put some refractory morter in there. Does this make sense? How much do suggest we grind out?
Deejayo, when you said we could fix the pointed dome issue w/ elbow grease what did you mean? I'm ok if we have a small performance loss as long as it isn't a structural problem.

[mrchipster]

Re: smoke coming out top of dome

500 is extremely high for your first day of curing. That is really day 6 or 7 curing heat. The crack does not look very serious from your photo but can you tell us how wide it is, and how long it travels.

Slow down on the heating by adding less wood, and if the fire goes out just wait until the next day to build another small fire.

[deejayoh]

Re: smoke coming out top of dome

To clarify, I meant fix the smoke problem, not the top. Elbow grease meaning the steps I suggested. I don't think the shape will be anything you really notice in the long run.

Chip's curing advice is good. you may have a crack that will settle down when the oven cools.

[david s]

Re: smoke coming out top of dome

Often once you have a crack, then you have it forever, however I've found this sometimes works.
1. Wet the crack with water and wait 10 mins
2. While waiting mix up a slurry using the cement component of your mortar (in the case of home brew 50/50 lime Portland cement.)
3. Paint this mixture in and around the crack from the inside and outside.Wait 10 mins again.
4. Squish your mor
4. Make up your mortar to a peanut butter consistency and squish it into the crack. Leave it proud of the surface on the outside, but sponge it clean on the inside.
5. Give it a week before firing it up.

Done this several times. Been about 50% successful.

[Bookemdanno]

Re: smoke coming out top of dome

If you've followed the basics of chain building, with tapered bricks, or wedges then simple mechanics will keep everything in place.
Have a bit of fun on the outside with a grinder to chase back to the brick level and follow Davids plan.
But i'd probably not worry about the inside. Parge up the outside once more and go steady with a few fires before your next full burn.

[Behen]

Re: smoke coming out top of dome

Thanks guys. We're pretty sure it's smoke coming through so we'll be grinding it out a bit and then fill it in. Two questions: should we wait to do the repair until after we've gone through several more curing fires say up to 600 or should we repair it first or doesn't it matter? Second if we repair first do we need to wait another week for it to set up before we start firing it again?

[david s]

Re: smoke coming out top of dome

I think you should repair now then wait a week before going back to fires again.

[CoyoteVB]

Re: smoke coming out top of dome

Don't Stress. I encounterd larger cracks. Attempts to fill or correct only worked temporarily. I finally gave in and insulated with ceramic blanket. The first layer was only 1" thick. after several full firings, I checked the banker. the area around the crack had been spoked but no damage... I added 5 more inched and put on the outer shell. No problems.