The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

DIY hearth oven from a propane grill

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Conjuay's picture
Conjuay

DIY hearth oven from a propane grill

I am in the process of converting a "42,000 BTU/hr" propane grill into a pizza/hearth oven. The grill is a used (and definately abused) three burner I found on craigslist. The box is rather large and mostly square, so lining it with firebrick shouldn't be difficult.


I tested it -without adding any new components- and it can produce 550* F .


I expected a higher reading; it is rated at 42,000 after all, but I was relying the grill's own therometer. I will test again with a better meter... and once most -but not all- of the bottom holes are covered with brick. (I know enough that propane sinks, and if one burner goes out...)


Anyway, this grill has a side burner that I was hoping to use for steam generation. I was thinking of incorperating a small pressure cooker and some high PSI copper tubing with a valve to serve that function.


I have 'googled': steam generation, DIY hearth oven, and a dozen different terms that I thought might give me some indication of how to proceed without scalding myself to death or causing a pressure cooker to explode, but I've come up with very little info.


I've been browsing the 'FornoBravo' forums, but they seem to frown on ANY oven that isn't wood fired.


Anyone here who has built a similiar contraption, I would love to hear back from you,


THNX


Mykl


 


 

ehanner's picture
ehanner

I have used fire brick stacked on the sides and back of my Weber Genesis gas grill. I lay a stone down and pre heat the whole thing for a while. It takes an hour to get the thermal mass warmed up. The results are pretty good and would be fine if the power goes out for any length of time. What it's missing is thermal mass in the lid. If I had one I didn't want to use as a grill again, I would find a way to mount terracotta clay tiles in the lid. But, opening it would require strength and caution.


I also have a 15 inch charcoal Weber that I cut out the bottom and heat it with a gas burner. This gets use as a pizza oven when I need to entertain myself. I can get it up to 650F which will bake a pizza in 3 minutes flat.


Eric

yozzause's picture
yozzause

I asked a rep from a welding supplies company that supplies goods to our plumbing section what they might have in the way of a gas flame thrower that could be used to heat the (wood) fired oven.


He did have a suggestion that they had a piece of equipement that applied a flame to sheet metal prior to it being processed that might work for me, i have yet to try it out, It would certainly be a good idea if smoke is a problem where the oven is situated and also if wood is poor quality.i do have to do a little more work to see if i can get a trial of the unit that he is suggesting but it will fit onto an lpg bottle


i have worked a  commercial oven with  a fuel oil burner that had a big air blower That would shoot a big flame into the chamber to heat  the oven inbetween bakes of italian breads so it will be a very similar principle, just make a stand for the flame thrower at the mouth of the oven.


regards Yozza

ehanner's picture
ehanner

Yozza,


Just remember that when you put the burning flame thrower into the oven, all the oxygen will be consumed pretty quickly by the flame. If there isn't an easy vent, the flame will be starved and eventually go out. When that starts to happen, you have a possibly for explosion or blow back. I like the idea of using gas when wood is scarce or I'm lazy. The "Fire below the chamber" concept is in my view the best way to go. This poilane video shows how you can do it. They don't show the vent chimney but it has to be built in for this to work. Any kind of fuel would work.


Eric

yozzause's picture
yozzause

Thanks Eric


The flame thrower would sit at the throat of the oven and the flame would be directed into the chamber it will have already pulled the oxygen that it needs, rather than sourcing it from the chamber. The commercial oven used a big electric blower that sounded like a jet engine whiring into life and you used to ready a naked flame and open the fuel jet and boom  away she went.


im still away off from trying the gas burner yet but do hope to try it soon


regards Yozza 

RobynNZ's picture
RobynNZ

The news here reported the WA fires started when an off-duty policeman created sparks with a grinder but ......

yozzause's picture
yozzause

Yes Robyn the fires were terrible my mother in law used to live at Roleystone so it will be interesting to see if the old place survived.


We do have from time to time total fire bans that prohibit hot metal work and anything that could be a source of ignition and even bans from moving vehicles in paddocks.


In the conditions that we have been experiencing high winds and high temps it doesnt take long before you have a raging inferno.


But worst still are the idiots that light fires deliberately.


The brave volunteer firefighters have our total admiration and although property was lost there was no loss of life.


I am about 30 klms from where the fires were, but it was still quite worrying whilst it was out of control!


Its a funny country, drowning one side and burning the other!


kind regards Yozza

Conjuay's picture
Conjuay

Flamethrowers?


Wait a minute!


No, it is a propane grill, and it will remain propane!


Ehanner, the present plan is firebrick sides and bottom, but fireclay attached to Stainless steel wire lathing (the stuff used to hold stucco to walls) in the lid. I am intending to use just clay and fine sand for this part; I don't know if I need any additional 'binding' material.


The lid is going to be cut so that only the very front of it will open, otherwise I would lose too much heat on every opening.


The original grill has a stationary warming tray that I might simply pace a second stone on, if the clay/ sand cover doesn't work out, but that will limit the size/kinds of loaves I can make.


But the thing I need some help on is the steam injecting part. I'm thinking of an old pressure cooker, on the side burner. But the valve to control it and how to plumb the pot itself is where I'm coming up short.


Any ideas?

ssor's picture
ssor

you have a secure lid. You ought not go for any pressure. with a gas flame you can control the steam very well. Try it with any kettle and a tight lid. Bring it to a boil so that the lid "dances" and then turn the burner way down.


For the lining you can buy furnace lining cement that is insulating. and quite ligt in weight.