#21  
Old 12-20-2009, 01:57 AM
nissanneill's Avatar
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Thumbs up Re: Brick Oven (Gas fired)

Hi Aldream,
your pictures tell the true story. Your fire is like putting a series of candles in the oven to heat it. The flames should be much bluer and 3 to 4 times the height.
I am assuming that your LPG cylinder is coupled to your jets through a pressure regulator - yes?
Well, let me tell you a story of a close friend who had a powder coating business and heated his oven with electric elements which proved too slow, only 2 firings per day, so he contracted a gas installation with a jet of natural gas squirting into a 8" diameter black steel pipe that went across the back 8ft of the oven and then 20 ft down the length and then 4 ft up towards the top of the oven. The pressure in the gas input line was 2 lbs/sq. inch (which is only permitted with a permit into commercial and industrial applications over here), when compared to a household pressure of only around 1/2 to 3/4 lbs/sq inch. However, the increased pressure would shoot a flame almost 20 odd feet through the pipe heating it to a glowing red hot in around 5 minutes.
I think that you need to contact a specialist who can professionally advise you an the proper and safe installation, but I feel that with lpg, you will not need a regulator.

Neill
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  #22  
Old 12-21-2009, 12:18 PM
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Default Re: Brick Oven (Gas fired)

That is true... the gas tank is coupled to pressure regulator, but I have set on the max. I played around witht he air/gas mixer; however, that is the best setting I was able to acheive. Unfortunately, I am not able to find a specialist around here.

I called the gas company and requested a regulator that has a higher pressure rating but they advised me that with the size of tank I have gas might freeze if I utilize a higher pressure regulator!

I think the first thing I will do is to replace the burners with normal CS ones.
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  #23  
Old 12-21-2009, 12:23 PM
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Default Re: Brick Oven (Gas fired)

For all those who asked about the insulation and bricks used in the oven, I called the guy who made it for me and he told me that the bricks are fire bricks (except the ones used on front door). As for the insulation, he told me that he used salt as an insulator under the floor bricks and on top of the dome. I remember he dumped many salt bags over the oven after building it.
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  #24  
Old 12-21-2009, 12:24 PM
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Default Re: Brick Oven (Gas fired)

oh, one more thing: he told me that I can increase the temperature of the oven floor by wiping it with a wet peice of cloth once in a while while the oven is heating up.

Last edited by Aldream; 12-21-2009 at 12:47 PM.
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  #25  
Old 12-21-2009, 01:04 PM
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Default Re: Brick Oven (Gas fired)

Quote:
Originally Posted by cannyfradock View Post
Aldream

Can't give you any advice the gas topic, but would like to compliment you on the brickwork in your pizza-oven. Very nice job, but they don't look like fire-bricks to me. What type of brick are they? Also nobody has asked you what type of insulation is under the hearth. If the hearth itself is'nt made from a heat retaining brick and their is no insulating layer between your slab and the hearth then this might cause you problems. There probably is, and I'm just summising.

Interesting thread. Shall keep tuned in and I hope you find a solution to your problem.

Terry (C.F)
Thank you for the compliment. The guy who built it for me did a good job. I will try to take more pictures of the oven from the outside and also the chimney and post them here. I had also a fire place built from these bricks which I will try to also post here.
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  #26  
Old 12-21-2009, 02:16 PM
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Default Re: Brick Oven (Gas fired)

Aldream

I built my wood-oven by masonry experience and guesstimation. I came across this forum AFTER my build and I'm sure that if I described exactly how my oven was built, I would have recieved a lot of constructive criticism. I believe that is what you have recieved in the latest posts to your thread. After following this forum for a while I realise that the people of knowledge on this forum are only voicing their genuine concerns, and giving you the benifit of their experience

Keep battling on with your original concerns about your wood-oven and USE the comments voiced to find a solution.

Best of luck

Terry (C.F)
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  #27  
Old 12-21-2009, 02:25 PM
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Default Re: Brick Oven (Gas fired)

Quote:
Originally Posted by cannyfradock View Post
Aldream

I built my wood-oven by masonry experience and guesstimation. I came across this forum AFTER my build and I'm sure that if I described exactly how my oven was built, I would have recieved a lot of constructive criticism. I believe that is what you have recieved in the latest posts to your thread. After following this forum for a while I realise that the people of knowledge on this forum are only voicing their genuine concerns, and giving you the benifit of their experience

Keep battling on with your original concerns about your wood-oven and USE the comments voiced to find a solution.

Best of luck

Terry (C.F)
I do very much appreciate all the criticism I am receiving in this forum. I am learning and hoping that someone else will learn from my experience.
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  #28  
Old 12-23-2009, 04:53 AM
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Default Re: Brick Oven (Gas fired)

And, before we build a bigger fire is the flue adequate?

As far as running small LP tanks without a regulator it can be done and you can squirt a HUGE flame out the burner—but the tank will chill and gas flow will diminish to something that is probably less than adequate for heating all this masonry. I have a 450,000 BTU weed burner attached to a 30# unregulated cylinder that will put out a flame-and-a-half—it's impressive!! But after a few minutes of wide-open burning the tank does develop frost on the outside and fuel pressure/flow drops, limiting the flame size and heat output.
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  #29  
Old 12-23-2009, 01:59 PM
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Default Re: Brick Oven (Gas fired)

Quote:
Originally Posted by lwalper View Post
And, before we build a bigger fire is the flue adequate?

As far as running small LP tanks without a regulator it can be done and you can squirt a HUGE flame out the burner—but the tank will chill and gas flow will diminish to something that is probably less than adequate for heating all this masonry. I have a 450,000 BTU weed burner attached to a 30# unregulated cylinder that will put out a flame-and-a-half—it's impressive!! But after a few minutes of wide-open burning the tank does develop frost on the outside and fuel pressure/flow drops, limiting the flame size and heat output.
I think I have got a problem with my burners. The flame they shoot is mostly yellow in colour. If I increase the air opening, the flame starts getting bluer but it gets shorter and blows away from the burner. I am now doing some reading on burners and hopefully I will know why I have this problem. Although I have already decided to change the burners since they are galvanized steel as recommended by dmun earlier in this thread, but I want to make sure that I have the right design before doing that.
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  #30  
Old 12-23-2009, 06:39 PM
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Default Re: Brick Oven (Gas fired)

Yep, those are HUGE holes in the pipe. At low pressures and gas flows that's great, but when the flow increases you will blow more gas and blow it faster than the flame front can travel. There's a particular velocity that gases in various air/fuel mixtures like to burn. You're blowing pure fuel out those holes and snuffing out the flame with excess fuel (more than it can burn at the time). What you've got there is a good setup for a fireplace, but not so good for what you're trying to accomplish.

Check these Raku venturi burners: Ward Burner Systems - Power Burners, Raku Burners, and Kilns

They'll put some heat in your oven!

You might also look at getting a tank with a horizontal configuration which will give more surface area for the gas to change from a liquid to a vapor in the tank—or, tilt the existing tank about 15-20 degrees - that will accomplish the same thing. Just beware that when you tilt the tank there is always the possibility of squirting LIQUID fuel out the burner nozzle which makes a REALLY BIG and probably unexpected flame (read: DANGEROUS!!)

Last edited by lwalper; 12-23-2009 at 06:47 PM.
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