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Propane pre-heating in WFO??? Possible or crazy?

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  • Propane pre-heating in WFO??? Possible or crazy?

    Good morning everyone,

    I built my WFO and have completed the curing stages, now it’s time to begin enjoying all of the hard work to this point. I have a question for all those here on the forum. My problem in attempting to use the oven in the evening is preheating it for the number of hours required to get to the proper cooking temperature. I simply don’t have the time in life to sit and slowly build temperature prior to cooking, so I began thinking how I could expedite the process or at least set it on “cruise control” for a couple of hours. I came up with using some sort of propane burner to begin “ heat soaking” the interior. I’m sure others have done it, but before I begin building something, I just wanted to put it out there and get your opinions.

    Here’s my idea. Build a black pipe square burner out of 1/2” pipe and a bunch of 90* elbows. Drilling holes both on top and bottom and standing it off the floor 2-3”. Smaller holes directed at the floor and slightly larger on top to heat the interior of the oven. An extension pipe out the oven opening to a 90 pointing down to a connection on a variable regulator hooked to a 20# propane tank. I got the idea looking at how people build DIY fire pit burners and figured it would work in a WFO. I could set it at a certain flame height to begin and slowly increase the flame/temp up every hour or so until I reach a given temp. At that point, remove the burner and throw in my wood to achieve the final cooking temperature and get the flavor of the particular wood I will be cooking with.

    Crazy or possible? -lease give me your thoughts or point me toward a build where someone has already done this so I don’t have to do all of the experimenting.

    Thanks as always, Dan
    My newbie build thread: https://community.fornobravo.com/for...ie-ready-to-go

  • #2
    Nobody? Really? I would have thought this has been done over and over again. Regardless, I ran it through in my head and it should work, so I built one this afternoon. Made from 1/2” black pipe and lots of fittings. Tomorrow I will drag a 20# propane cylinder with me down to the shop, grab a regulator/hose assembly and an adjustable valve. I have 1/16” holes drilled in the bottom of the pipes to heat the floor and 1/8” holes on top to heat the chamber and dome. I will report back tomorrow night with either good news or photos of burnt hair on my arms.Click image for larger version

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    My newbie build thread: https://community.fornobravo.com/for...ie-ready-to-go

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    • #3
      Originally posted by w650gb500 View Post
      Nobody? Really? I would have thought this has been done over and over again. Regardless, I ran it through in my head and it should work, so I built one this afternoon. Made from 1/2” black pipe and lots of fittings. Tomorrow I will drag a 20# propane cylinder with me down to the shop, grab a regulator/hose assembly and an adjustable valve. I have 1/16” holes drilled in the bottom of the pipes to heat the floor and 1/8” holes on top to heat the chamber and dome. I will report back tomorrow night with either good news or photos of burnt hair on my arms.Click image for larger version  Name:	0C62C314-0AF2-4C13-9E4A-81D01575DA8A.jpeg Views:	0 Size:	130.4 KB ID:	440744
      As Russell has said, DIY gas is not recommended. Having said that, I'd be keen to see it fired up. :-)
      My 42" build: https://community.fornobravo.com/for...ld-new-zealand
      My oven drawings: My oven drawings - Forno Bravo Forum: The Wood-Fired Oven Community

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      • #4
        Originally posted by UtahBeehiver
        Typically the forum does not comment on DIY gas or propane oven heating devices that have not been UL approved for safety reasons.

        I understand that a forum may not want to have an open discussion but I am a bit confused. This is a DIY forum as is most of the Internet and social sites nowadays. Most of the WFO construction done here by members is “loosely based” on what others have found to work and adapted to their own use based on their individual building experience, available building materials, space constraints and mostly budget. I would bet that most(80% or more) are not built with permits if applicable, not built to local building code or IBC, not built by a bonded/insured and licensed contractor and don’t have any type of UL approved spark arrestor on the chimney. I was in the insurance industry for nearly 12 years from an agent to a broker, then as an adjuster, an appraiser and a BI(bodily injury) negotiator. I haven’t looked into it, but I would guess that our WFO’s, if they caused a fire to our homes or an adjacent property, would be scrutinized very closely by an insurance adjuster to see whether a claim would be paid by your homeowners coverage or denied due to the reasons I listed above.

        We all take a chance when building these ovens and I gladly jumped-in with both feet. I don’t believe the propane pre-heater will be an issue and accept the liability in building it. If it is against the forum rules to discuss its use, that’s fine. If this thread can stay here, I can link a YouTube video of it in use, that would be great. No need for comments, just whether it works or not for informational purposes.

        Thanks again for all this forum has done in getting my oven built and performing properly. The last thing I want to do is cause anything I might post here to be of questionable content.
        My newbie build thread: https://community.fornobravo.com/for...ie-ready-to-go

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        • #5
          Russell,

          I appreciate all your posts to help us. I want to make sure I do it right (and once) when I finally pull the trigger.

          Giovanni

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          • #6
            OK, so here is a link to my initial lighting of the pre-heater. If this link or discussion is against forum rules, please have a moderator delete it. I don’t want to do anything that the community might deem as dangerous.



            I will be happy to answer any questions either here on the public forum of privately via messenger. I will be trying it in the oven on Saturday afternoon/evening and will report back.
            My newbie build thread: https://community.fornobravo.com/for...ie-ready-to-go

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            • #7
              Finally back to this topic after a few months of use. Let me just say that this “home-built pre-heater” has been an absolute game changer for us using our WFO. Previous to building this, it would take me 3-4 hours to slowly heat up the oven to cooking temperature. I cook with my floor temperature at 625-650* and to avoid damage/cracking of my cast oven, it took that long. With this heater, I connect it to the 20# LP tank, light it, insert it into the oven on a very “low flame setting” and leave it there for an hour before going back to check on it. Then the next hour, it gets turned up slightly. I can only do this by eye and judging the size/length of the flame. Let it go for another hour and then revisit it for the last hour of use at a slightly larger flame. In the 3 hours of use, I can slowly get the floor to 450*. I then turn it off, disconnect the LP tank, remove the burner and start a small wood fire. I only need to sit by the oven and “baby sit” the fire for 1 hour before cooking rather than 4 hours of tending to a slowly building fire. It gives me time to do all of my food prep work, cut the grass, get the cushions on the outdoor furniture and grab a shower before company arrives. Also, rather than 4 hours throwing small sticks into the oven and drinking beer, I now only have one hour of consuming adult beverages, so the pizzas are much more consistent being made by a sober pizziaoli rather than a drunk one!

              **** DISCLAIMER**** Although this has worked well for me and has made using our oven much more enjoyable, this is only my experience. If someone were to copy this and build their own, do so with the utmost of caution. It can be very dangerous or worse! I don’t believe I would be using the oven nearly as much if I had to continue spending 4 hours heating it up just to cook in it for an hour or so, but this is just my opinion. I think it changes the whole way that I look at using it, more so than a chore that it was becoming. It would waste 1/2 the day getting ready, running up and down the stairs to and from the kitchen prepping and trying to keep the fire going. But, no longer since this pre-heater works so well. I hope this was at least a little bit informational, but again, move forward at your own pace and PLEASE BE CAREFUL!!!!
              Last edited by w650gb500; 11-09-2021, 11:39 AM.
              My newbie build thread: https://community.fornobravo.com/for...ie-ready-to-go

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              • #8
                Glad it works for your situation and appreciate the "disclaimer" of caveat emptor.
                Russell
                Google Photo Album [https://photos.google.com/share/AF1Q...JneXVXc3hVNHd3/]

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                • #9
                  Nice write up - with the ~3 hours of burn per oven heating cycle, how many cycles do you estimate you get from a full #20 lb tank?
                  My build thread
                  https://community.fornobravo.com/for...h-corner-build

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                  • #10
                    Difficult to say since I don’t have a tank dedicated solely to heating the oven. It gets moved around and used in our upstairs fire pit and grill. I recently purchased 2 additional tanks and one will be just for the WFO. But, if I had to guess and based on the size of the flame, weight of the cylinder when moving it and considering I left one of our heaters on all night Saturday from 5:00pm until I realized it at 9:00am the next morning, I would guess I could easily get 10 firings. That’s probably a conservative number. LP gas here is $15 per refill currently. Even if a tank only lasted 3 firings, the $5 would be well worth not having to sit by the fire and drink. I think it’s 10+ uses I could get out of a tank.

                    Here is a picture of the flame in the oven on the low setting.
                    Click image for larger version

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                    Here is one on the highest setting.
                    Click image for larger version

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                    My newbie build thread: https://community.fornobravo.com/for...ie-ready-to-go

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                    • #11
                      Making up a homemade gas burner set up has been a taboo subject on this forum because of the safety aspect. I’m not sure of the current policy, but someone else may chime in. The burner should be fitted with a flame failure device (I don’t see one with your set up), as filling a hot oven with gas is a potentially dangerous situation. The problem is further compounded if wood is also used because it can provide an ignition source for unignited gas.
                      Kindled with zeal and fired with passion.

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                      • #12
                        Taboo subject or not, I think I'm going to build one! Although, I may use a standard cast iron burner available here as a "wok" burner. As it would have all the fail safe devices all I'd need to do is add a steel pipe to extend the location of the regulator and hose to outside the oven.
                        My 42" build: https://community.fornobravo.com/for...ld-new-zealand
                        My oven drawings: My oven drawings - Forno Bravo Forum: The Wood-Fired Oven Community

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                        • #13
                          Originally posted by MarkJerling View Post
                          Taboo subject or not, I think I'm going to build one! Although, I may use a standard cast iron burner available here as a "wok" burner. As it would have all the fail safe devices all I'd need to do is add a steel pipe to extend the location of the regulator and hose to outside the oven.
                          No, a wok burner does not have a flame failure device attached as it is not designed to be used in an enclosed chamber.
                          Kindled with zeal and fired with passion.

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                          • #14
                            Originally posted by david s View Post

                            No, a wok burner does not have a flame failure device attached as it is not designed to be used in an enclosed chamber.
                            Here, all wok burners designed for indoor use must have a flame failure device, per AS/NZS 5263.1.1:2016. Outdoor use wok burners do not require a flame failure device.
                            My 42" build: https://community.fornobravo.com/for...ld-new-zealand
                            My oven drawings: My oven drawings - Forno Bravo Forum: The Wood-Fired Oven Community

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                            • #15
                              Indoor or outdoor doesn't matter when your safety is of concern. An oven is a confined space where the collection of combustible gasses can occur..............with your face at the opening when they can ignite
                              Joe Watson " A year from now, you will wish that you had started today" My Build Album / My Build

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