mattb Posted February 23 Report Share Posted February 23 Hello all, First post here, but I've been using it as research for a few months now. Little background I've only been involved with pottery for a bit less than a year now, mostly as a way to give my mostly blind wife a hobby (I personally have to many, or maybe not enough, depending on who you ask, as my new phrase has become, my hobby is collecting hobbies). I've been a refractory bricklayer for many years, and most recently I repair and install electric kilns, as well as work for a ceramics dealer, so building my own tools or modifying other ones is not an issue for me. I recently acquired a amaco ah30 kiln and believe this will be a decent donor kiln for converting to gas. Yes I can and could build one however I'd like, but being the frugal guy I am, this kiln seems to fit the bill for my current wants/needs in terms of cubic feet and price (I was paid to remove it). As for my plans. I plan to run 2 burners coming in from the right side of the kiln front and back pointing towards the left side with the swinging door in the front, (through the electronics bay) with the flue/chimney in the center (running up through the electronics bay to the top). Since I'm 100% new to gas kilns (although I have done gas forges for blacksmithing) there are a couple things I'd like some guidance on. Firstly, size and location of the flue. I'm thinking bottom center essentially in between the 2 bagwalls from the burners, but how large of an opening is suggested for the flue/chimney? secondly target bricks on the left wall, just a hard brick cut at a 45? Thirdly, the kiln has a 20x20 opening between the walls (l/r and f/b), how much room around shelves is recommended? 16x16 shelves with 2 inches around or 18x18 for a 1 inch opening on the perimeter? If the controller still works Ill probably rewire it to just use the thermocouple zone control/monitoring since I wont need 240 for running elements. If not I'll do something else for t/c's. I'm sure I'll find something else I need to ask about, but this should be a good start of conversation. thank you all in advance, matt Hyn Patty 1 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 23 Report Share Posted February 23 Hi @mattb, and welcome to the forum. It would help if you could draw a picture of your plans. Here are some questions I have based on my understanding of the project: You're making it a downdraft, correct? What is the btu output of your burners? Powered burners or venturi? Natural gas or propane? What are you using for a safety system on the burners- Baso valve? Why do you want to run everything through the electronics bay? Seems like a lot of hassle to work in there, and you'll be restricting airflow for the burners. How do you plan to construct the chimney? Use 16x16 shelves. It needs space to breathe. You can rewire the control transformer to run the controller on 120V if you want to use the thermocouple. I'd put the thermocouple in a protection tube or it won't last long if you plan to fire in reduction. You can put the flue opening between the burner ports. Make the flue opening equal to the total area of the burner ports. You can always damper it down. The bottom shelf will need to be above the burner ports. Have a bag wall for each burner under the shelf. Target bricks can just be a brick leaning against the wall at the end of the firebox, or a brick set upright but turned at an angle to the burners about 2/3 of the way from the burner. Hyn Patty 1 Quote Link to comment Share on other sites More sharing options...
mattb Posted February 23 Author Report Share Posted February 23 Bottom shelf. I figure I'd use hardback as the bagwalls and set the shelf on top of them. According to my research which is incomplete, baso valves seem to be the way to go and I will do more research before making final decisions on plumbing the burners. Propane is what I plan to use. Burners have not been decided on yet, however off the top of my head a single 200k btu should be sufficient, however I figure 2 150-200k burners will be better so I don't need run full tilt. I built my own n/a burners for my gas forge so I'll need to dig out my old notes and I may build my own. Electronics bay runs the depth 24ish inches and the full height of the kiln on the right side. It's more like a closet on the side. It is a bit narrow at about 8 inches so I'll probably have weld some additional sheet metal to surround the entire chimney. I'll probably keep this kiln outdoors so I want to protect the brick. But who knows I may move it indoors after my garage is finished. Chimney, I'll build it out of recycled soft brick from other kilns. It should be rather easy for me to mount the burners and lay the chimney based on the way the electronics bay is. It might be easier to understand if a pic of the kiln was googled. For now here's my phone drawing of how I plan to lay out the inside. Matt Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 24 Report Share Posted February 24 3 hours ago, mattb said: baso valves seem to be the way to go and I will do more research before making final decisions on plumbing the burners. Propane is what I plan to use. Baso makes lots of valves, high pressure and thermocouple powered are attractive for minimal design. That kiln is 20” X 20” X36” h so not a lot of width for burners on each side and bag walls but height might be key. You may end up atmospheric through the bottom or single powered burner. Looks like a fun project. I did find this through Google. Not dimensional but appears proportional. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 24 Report Share Posted February 24 5 hours ago, mattb said: It might be easier to understand if a pic of the kiln was googled. I've seen that kiln, which is why I don't think the electronics bay is suitable for the burners. It's probably too shallow to house the burners, and I don't know how you'll be able to get to them to make adjustments during the firing if they're enclosed. Plus you don't want anything to restrict air flow around the burners. I would cut out a big panel from the right side of the cabinet from kiln floor level to the top so you have a nice open space to work within. Make the chimney a full brick thick (4.5"), and put in a damper about 1/3 of the way up from the bottom. 5 hours ago, mattb said: baso valves seem to be the way to go and I will do more research before making final decisions on plumbing the burners. Baso with a simple thermocouple and pilot light like an old school water heater will work well and be a cost-effective safety system. 5 hours ago, mattb said: I built my own n/a burners for my gas forge so I'll need to dig out my old notes and I may build my own. Just thought- if you make a power burner (with a blower) you'd only need one, and it would also eliminate the need for a very tall chimney. The chimney height is the number one issue we see here on the forum when it comes to successfully firing converting kilns. Most of those use venturi (n/a) burners, which are cheap but require a good dose of secondary air to fire properly, which comes from a taller chimney. With a power burner the chimney doesn't need to be any taller than the top the kiln. Having the front wall of the controller cabinet would also allow for mounting a rheostat for the blower. This kiln is a much better candidate for conversion than the majority of kilns we see here. It should work well. Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
mattb Posted February 24 Author Report Share Posted February 24 as stated im 100% new to gas kilns, so thank you both, as well as anyone else who happens to chime in later. a better drawing, now that im in front of a comp. my thoughts were 4" burner openings with 1 inch on either side of them with a 1 inch bagwall. now that would leave 6 inches in the center. however reading above it sounds like if i have 2 burner ports at 4" i should have 8 inches for the flue? if that is correct i could move the bagwalls over 1 inch and re-center the burner which would then give me 8. now i guess maybe i should ask, what size opening should i have as a burner port opening? im aware this will depend on burner size, but should i shoot for 1 inch wider diameter than the burner nozzle, or maybe 2? knowing this even if it is an average number should help me when determining the built or bought burners. again im a complete newb when it comes to gas kilns, the way i understand it the burners sit outside of the burner port, unlike my gas forge where i stuck the burner down inside the chamber. granted my knowledge on that subject comes mostly from watching youtube videos where people convert top loading kilns. as for chimney height, would the 36ish inches from the bottom of the chamber/flue to the top of the kiln be sufficient? or should i consider that i may need to take it higher? this would determine my fabrication needs on the chimney. granted i can always easily add to it later if need be, but id rather not do it nice because i did it twice, if possible. on my drawing above in haste i completely forgot to consider the 17 inches of brick when i put 24 inches for the depth of the kiln. so the overall depth of the kiln is more in the 40 inch range (not that it matters for the chamber). Quote Link to comment Share on other sites More sharing options...
mattb Posted February 24 Author Report Share Posted February 24 9 minutes ago, neilestrick said: Just thought- if you make a power burner (with a blower) you'd only need one, and it would also eliminate the need for a very tall chimney. The chimney height is the number one issue we see here on the forum when it comes to successfully firing converting kilns. Most of those use venturi (n/a) burners, which are cheap but require a good dose of secondary air to fire properly, which comes from a taller chimney. With a power burner the chimney doesn't need to be any taller than the top the kiln. Having the front wall of the controller cabinet would also allow for mounting a rheostat for the blower. looks like you beat me to the punch on the chimney question. what kind of cfm would you suggest if i were to build or just purchase a power burner? I'll most definitely be researching this probably before you answer back, but hey it feels more personal getting an answer than just reading things. also if i move to a single burner how would you suggest my layout change for even heating? Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 24 Report Share Posted February 24 The size of your burner ports will depend on the size of your burner tips. The port should be about an inch wider in diameter than the burner tip. The end of the burner should be set back from the kiln wall 1/4" for every inch of burner tip diameter. I don't know how you'll make a bag wall that's only 1" wide and stay standing. Typically the bag wall is made of hard brick, set on side, so 2-2.5" in order to be stable. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 24 Report Share Posted February 24 5 minutes ago, mattb said: looks like you beat me to the punch on the chimney question. what kind of cfm would you suggest if i were to build or just purchase a power burner? I'll most definitely be researching this probably before you answer back, but hey it feels more personal getting an answer than just reading things. also if i move to a single burner how would you suggest my layout change for even heating? CFM of the blower will depend on the btu output needs, but for something small like this a little 50cfm squirrel cage blower would probably work. You'll want to have a rheostat on it to slow it down. The nice thing about a power burner is you can resize the gas orifice and get a really wide range of output without making any significant changes to the setup. If you really want to make it safe, put a solenoid on the gas line and connect to it a high limit shutoff, in addition to the Baso pilot system. This is one of a pair of burners I built a long time ago for a gas kiln I no longer have. About 450K btu each. Baso, solenoid, rheostat, high temp shutoff, timer. About as safe as I could make it with off-the-shelf parts and without getting into complex and expensive control systems. These can get pricey by the time you buy all the parts, but they work well and are quite safe. Ward Burner Systems is a good resource for burner info. Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
mattb Posted February 24 Author Report Share Posted February 24 10 minutes ago, neilestrick said: I don't know how you'll make a bag wall that's only 1" wide and stay standing. Typically the bag wall is made of hard brick, set on side, so 2-2.5" in order to be stable. creativity my friend, route a .5" deep by 1" wide slot in the floor and a 2" deep slot in each end wall for the splits to fit into. use sairset or no. 36 to mortar the entire thing into place. yes if and when the lower shelf needs to be removed and inserted it would need to be done carefully to avoid breaking anything. but hey when you have minimal space you gotta pick up every inch you can. thank you for the burner location information. that was what i was thinking it needed to be. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 24 Report Share Posted February 24 23 minutes ago, mattb said: also if i move to a single burner how would you suggest my layout change for even heating? Bring the burner in along one wall, and have the flue opening centered on the opposite wall. Put a target brick about halfway in. Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 24 Report Share Posted February 24 2 minutes ago, mattb said: creativity my friend, route a .5" deep by 1" wide slot in the floor and a 2" deep slot in each end wall for the splits to fit into. use sairset or no. 36 to mortar the entire thing into place. yes if and when the lower shelf needs to be removed and inserted it would need to be done carefully to avoid breaking anything. but hey when you have minimal space you gotta pick up every inch you can. I would be very concerned with the splits warping, at which point the brick slots will crack and the mortar joints will fail. IFB are not strong at all. I certainly wouldn't trust them to support the kiln shelves above, although that can probably be dealt with in other ways. The firebox is the hottest point in the kiln, and the burners blasting on one side of a brick is about as uneven a heating situation as you can get in a kiln, so lots of movement there. Alpine kilns used to use a silicon carbide kiln shelf as a bag wall, notched in to the front and back walls of the kiln. They always cracked the bricks where they were notched in, at which point you had to switch to free stacked bricks, which could move as needed during expansion/contraction. Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 24 Report Share Posted February 24 (edited) 3 hours ago, mattb said: what kind of cfm would you suggest if i were to build or just purchase a power burner? I'll most definitely be researching this probably before you answer back, but hey it feels more personal getting an answer than just reading things. Just some thoughts that might help here - nail down your approximate design heat requirements. One simple way to look at this is presently how much thermal energy does it take brand new out of the box electric. This kiln is a 16 kw so at 100% conversion efficiency, to make cone 10. 16,000w x 3.41 btu/w = 54560 btuh. That is totally sealed and converting 100% of your energy to useable heat. So estimating (approximate) Any gas burner you install will be 80% or less efficient which could range let’s say 60-80%. So minimum ballpark thermal energy range needed with no flue 54560/0.80 = 68,200 btuh min and 54560/0.60=90,933 btuh max.. But we know you need a flue so realistically 100,000 to 150,000 btuh will be necessary. From there you can begin picking approximate flue height, burner cfm, orifice sizes, etc… mostly from tables. To answer your question of approximate burner cfm: Burner CFM / secondary air cfm required from previous thread (table) Propane requires 23.82 cu ft of air for every cu ft of propane to completely combust (oxidation firing). 50% of which will come as primary and 50% secondary air. Previous thread here Maybe approximate your thermal needs or range first, then pick your other needs from tables. Edited February 24 by Bill Kielb Quote Link to comment Share on other sites More sharing options...
mattb Posted February 24 Author Report Share Posted February 24 8 hours ago, neilestrick said: I would be very concerned with the splits warping, at which point the brick slots will crack and the mortar joints will fail. IFB are not strong at all. i had entirely planned to use hard brick for this, but you are correct I could definitely foresee the potential for warping on a 1" split even with the hard bricks, as well as the potential for cracking at the slots either below or on the end wall joints due to one uneven heating of the split surface. 8 hours ago, neilestrick said: Ward Burner Systems is a good resource for burner info. i have not had a chance to research here yet but will definitely do so today, as the idea of a single powered burner is a possibility i didnt really consider. 6 hours ago, Bill Kielb said: Just some thoughts that might help here - nail down your approximate design heat requirements in my second post i mentioned that off the top of my head i said a single 200k burner should be sufficient. i used this data to get my number. If you have a soft brick kiln with 9" walls, you'll need: 6,000 - 10,000 BTU/CF for cone 06, 8,000 - 13,000 BTU/CF for cone 6, and 10,000 - 16,000 BTU/CF for cone 10. i then took the high end of 16000 and multiplied by 8.3 for the cubic foot inside the chamber which gives me 133k roughly. i added some additional being as the lining is 8.5 inches but has approx 3/4 inch cutouts on most walls and floors. however i had thought using 2 lower rated burners but stills added together went well above my needed range should allow the kiln to work without having to run at full tilt. the things i seem to be having the most trouble finding out are the draft requirements, as i am not sure how the airflow really works inside of a kiln like this. you have both given me things to consider and later i will take some time and create a new drawing based on the ideas given to me to hopefully be critiqued and pointed in the right direction. this is the reason i came here, to get the advice of those more knowledgeable than me, so thank you again. matt Hulk 1 Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 24 Report Share Posted February 24 I've been thinking about this some more. I think that if you really want to be sure that it works well, I would do smaller shelves and leave a firebox zone. There's a tendency to want to fill these kilns with as much shelving as possible, because that's how it worked when used as an electric kiln. But if you were building a gas kiln from scratch you wouldn't do it that way. While it can work with 16x16 shelves, it won't fire nearly as nicely or easily as it could/should. By using smaller shelves and leaving a firebox, it's going to fire much better, and have more options for making adjustments. Specifically, I'm thinking of the bag wall, which will undoubtedly need to be adjusted up or down, and so leaving enough space for that is important. If you go with a single burner you can bring it in from the side. If you go with two burners, bring them in from the bottom: This design leaves room for a 5-6" wide firebox, which is really about the smallest you can functionally go. The 2.25" wide bag wall is made of regular 4.5" hard bricks cut in half. It's narrow but stable. You could increase the size of the shelf all the way to the edge of the firebox by letting it sit on a short bag wall, and then put more bag wall on top of the shelf. Then you'd have a roughly 17x14 shelf all the way up. I've built little kilns like this and they fired beautifully. Quote Link to comment Share on other sites More sharing options...
mattb Posted February 24 Author Report Share Posted February 24 10 hours ago, neilestrick said: Bring the burner in along one wall, and have the flue opening centered on the opposite wall. Put a target brick about halfway in. im going to finish this post as i started it before i had to step out and before you posted your most recent comment, but i do like the ideas youve shown me., but since im trying to learn aswell i figure it wont hurt to ask this question. i am fine with a firing chamber slightly smaller. i am adding 3 drawings/screenshots. the one i believe is how you suggested. the second 2 would put the burner in the center and have a flue on either side that could either run 2 chimneys straight up or they could taper into a single chimney in the center. yes it would require some fabrication and extra brick either way. this is simply a design idea i had to keep everything on one side of the kiln. im aware this is probably overcomplicating things, but again if im not asking questions i wouldnt be learning what works, what doesnt, and hopefully why. i do like youre second drawing of the double burner setup from underneath. i dont remember the height of the storage area under the chamber of the kiln but i believe it is atleast 20 inches, which should give me plenty of room for burners. i may need to see about an additional way to improve draw of air under the kiln if i use venturi burners, but that should be simple enough. yo once again thank you for your time, as well as sharing your ideas. Quote Link to comment Share on other sites More sharing options...
Mark C. Posted February 24 Report Share Posted February 24 instead of me addding to the how to ,I suggest this kiln conversion site as its all covered here by many Its the kiln conversion facebook group just about these type of kilns https://www.facebook.com/groups/4124895130900261 Quote Link to comment Share on other sites More sharing options...
mattb Posted February 24 Author Report Share Posted February 24 Thank you I'll check it out Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted February 24 Report Share Posted February 24 7 hours ago, mattb said: things i seem to be having the most trouble finding out are the draft requirements, as i am not sure how the airflow really works inside of a kiln like this. For a quick approx guide: https://www.engineeringtoolbox.com/chimney-area-heat-load-d_1132.html you will basically need to be able to remove all the cfm in your kiln so primary air, sec air and propane cfm, …… worst case at lower temperatures, which won’t really happen. You won’t start your kiln at full blast. The chart above is reasonable. If you want to calculate draft in inches of WC there are some simple formulas to approximate as well. Over designing the area requirements or flue diameter reduces the scrubbing velocity of the flue gasses. Better to increase height as needed than increasing the diameter/ area a bunch Quote Link to comment Share on other sites More sharing options...
mattb Posted February 25 Author Report Share Posted February 25 this is the start of what I'm envisioning based on your sketch. i plan to go get the dimensions of the electronics bay as well as the under chamber storage to try and get a finished design concept, later today. as for bagwall height, im guessing this may be trial and error, but maybe a recommended starting wouldnt be bad. should the bagwall essentially be level with the first shelf? i know in one post i mentioned when you have minimal space youve got to try and pick up every inch you can, and in another post said I dont mind going smaller on kiln space. this sounds very contradictory, so for maybe future readers i should clarify. when i talk about using every inch available i meant to just not have wasted space. use every inch in its best way, even if that means i get less square footage for shelves, as long as the space is used proportionally my goals will have been achieved. please disregard the soldier brick on the chimney, stupid inventor wouldnt let me turn them sideways (probably my lack of skill with the tool). Quote Link to comment Share on other sites More sharing options...
Hyn Patty Posted February 25 Report Share Posted February 25 I know nothing about gas kilns and have always used electric. Kudos to you guys. I have nothing helpful to input, just popcorning while I read along and try to learn something kewl. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 25 Report Share Posted February 25 3 hours ago, mattb said: this is the start of what I'm envisioning based on your sketch. To be clear, my sketches are top view. If you're using two venturi burners have them come up from the bottom. If you're using a single power burner have it come from the side. The bottom shelf should be an inch or so off the floor. The bag wall will need to be at least as tall as the top of the burner ports, probably a few inches above that. Trial and error indeed. It's going to force heat upwards before it can be pulled down by the flue, and protect the pots along the firebox. Quote Link to comment Share on other sites More sharing options...
mattb Posted February 25 Author Report Share Posted February 25 the drawing is looking down from the top or in from the front depending on how you look at the drawing, it has been angled so i could show the inside. im still considering the single burner from the back wall rather than 2 venturi from the bottom due to having to raise the chimney. speaking of chimney, is there any reason i couldnt use say normal pipe stack chimney (not brick, like coal stove) coming off the top to gain the additional height i may need? as in i would have the 45ish inches of brick chimney with the additional as pipe stack? not that i couldnt make a brick chimney that just gets placed on top, just pipe would be lighter and easier to take on and off if i needed to move the kiln or cover it when not in use and inclement weather. I'll continue to research this next question on my own, but figure it cant hurt to ask here. does length of burner matter. I know, i know, i keep trying to keep everything on one side of the kiln, i do this mostly because i just want as clean a look as possible. im not married to the idea, but im sure trying to keep the engagement going... id be willing to bet the length is less of an issue with powered, and more so with venturi due to a long draft. also do they need to be in a straight line, or are bends (90/180) how pipe is run. id also assume my last statement is true here as well. although i guess it might not matter at all as long as there is enough gas pressure to push to the end of the pipe. Quote Link to comment Share on other sites More sharing options...
mattb Posted February 26 Author Report Share Posted February 26 The more i think about it i do like the idea of a powered single burner. if i plan to run electric for the control panel anyway, i might as well plug in a fan while im at it. ward burners was suggested as a place i look to for information. i have been thoroughly going over the numerous articles and information on that site for the past 2 days. the facebook group was also informative. i would assume ward burners are a reliable and suggested burner, since they were mentioned as a place to gather information. the sticker shock of their burners is not so bad and the fact i wont have to build it myself and chase gremlins is appealing to me. even the additional price of safety addons and 90 degree head, i dont feel as though i should penny pinch. as i stated, frugal but not cheap. with the mb200 and 400 being the same price is there any reason not to just get the largest one , even if it complete overkill, incase i want to go larger in the future? another chimney question. as of now i have it designed to use the current sidewall as the chimney face and lay a brick up leaving a 4.5 inch opening up the center. does the outside wall need to be thicker than say 3.5 inches? 4.5 has me poking past the outer dimensions of the shell. if i can drop this to 3.5 i could enclose the entire chimney. again id like it to look clean, look like it was meant to be there. im not particularly a form over funtion kind of guy, but if i can get form and function to go hand in hand, ill try... but who knows, well im hoping someone knows, maybe im completely off base and should have 9 inch chimney walls and i should build them from hardbrick rather than soft. that would be why im here though, to get the advice and knowledge of those whove already done this. my most recent design. i believe this is what you have me going for neil. Quote Link to comment Share on other sites More sharing options...
neilestrick Posted February 27 Report Share Posted February 27 If I'm interpreting your drawings correctly, I think you've got it. Don't forget you'll need a damper in the chimney, about 12-18" up from the floor. 4.5" walls would be better. Definitely soft brick. Don't oversize the burner. That can cause a lot of problems. Have you decided what type of gas you're going to use? Be sure to order the burner accordingly. Quote Link to comment Share on other sites More sharing options...
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