crb
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Posts posted by crb
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On 9/28/2023 at 12:23 PM, Bill Kielb said:
More and more pressure would indicate airflow issues, so did you ever come to terms with the operation of a damper? Also cycling on and off would indicate operating limit or high limit. How is this kiln controlled? Pictures here would help. I see pilot safety and a spark igniter in an earlier picture so this kiln likely has a high limit as well.
My best guess, the flue passage behind the back wall is restricted and not clear, so maybe collapsed somewhat and the high limit sensor might be located in this passage and not sensing the true temperature of the kiln or it is set low or just out of calibration.
So things to check: everything free, clear, not obstructed or collapsed …..l and how is the kiln safety or high limit intended to work?
Thank you!
Yep all correct, when the kiln had cooled I saw debris had fallen into the burners (I'd covered them but not well enough it seems!) gave it a good clean and now firing smoothly today but requires double the pressure again.I have the manual now kindly given by a member here and the pressure increase matches the sample firing given in the manual - just trying to get my head around why it needed less gas before. I think the kiln is now well-sealed and repaired, so is there less airflow? The dampers are adjusted at the top of the kiln across the top vent. I will take pictures.
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Good morning, almost a year and a half since I started this thread and the kiln has been firing consistently beautifully until this week.
My kiln roof collapsed (the lining inside) last week (it had been on its last legs for a while) and we replaced it at the weekend, replicating the same fitting and materials as before.
BUT my firing on Monday suddenly needed almost double the pressure to get to the top temp (150mb was enough to reach the top temp before -- this time it took to 250mb), today I started the kiln as normal at 6 this morning but still needed double the pressure to get the same temp rise and then about 2 hours into the firing the kiln started turning itself off and reigniting say about every 10/15mins.I've turned the whole system off, checked the valves were clear (as much as I could from the under and side I'm waiting for the kiln to cool to check no debris has fallen from inside the kiln) and swapped the bottles over to full tanks (although the other bottles still had half tanks). Restarted the kiln and again every 10/15mins the kiln shuts off and reignites.
I've got in touch with my gas plumber but just reaching out to see if anyone has had the same problem/has any ideas about what's going on?
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On 3/15/2022 at 4:07 PM, neilestrick said:
Were you dampering the flue at all? You'll need to. Kind of an odd setup to have the flue 90 degrees to the burners. For a single burner inlet it would be better to have the flue on the opposite side. It'll be interesting to see if you get cold spots in the front left corner.
Hi Neil, I did get a cold spot in the front left, is there anything I can do to counteract this?
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The regulator -- the manual specifies up to 300mb so 30mb was going to be tricky to get to top temp I think...
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Thank you so much for all your help, I managed to find someone who has the same kiln as me and the manual!! So the correct regulator is in and she is firing beautifully. @Bill Kielb thank you for your detailed firing tips I followed it today and looking forward to opening the results on Saturday! Thank you also @Mark C. for all your help!
- Hulk and Bill Kielb
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On 3/14/2022 at 4:16 PM, Mark C. said:
As an alternate way You may with a chop stick and a piece of tape tape a letter drill bit taped to the stick and drop that down thru kiln floor thru orfice to find the size (letter drills are sized exactly) In the UK you may have some other system of measurement ??I know you do. I think the regulator may be to restrictive-you should check that out.
I did this! A 0.85mm drill bit fit into the orifice of the gas burner
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1 hour ago, Mark C. said:
The back wall is a false wall with a long slots going up.
You will need a damper-ether brick or kiln shelve or fiber board. Bricks are the hardest to use for control
looks like you close the hole with those fiber scraps when done with fire?
Yes exactly, was planning on using the strips of fiber as dampers but also have kiln bricks
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37 minutes ago, neilestrick said:
Were you dampering the flue at all? You'll need to. Kind of an odd setup to have the flue 90 degrees to the burners. For a single burner inlet it would be better to have the flue on the opposite side. It'll be interesting to see if you get cold spots in the front left corner.
I hadnt reached 850/900 which is when I used to start using dampers in my old kilns. Would you recommend doing before then?
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1 minute ago, Bill Kielb said:
How do you damper this kiln while firing?
The previous owner slid fire bricks/or kiln shelves over these top slots for reduction, half way either side
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17 hours ago, Bill Kielb said:
My thought looking at this is we are going to find an issue with how the damper works or how it is being adjusted. Do you have a picture of the damper?
My feeling is this kiln will be extremely sensitive to very very small damper adjustments for a given gas pressure.
Nice kiln BTW!
Sorry not to have got the orifice sizes to you yet, don't have small enough drill bits and couldnt get them undone but I'm sure the plumber tomorrow will have something he can measure them for me!
No damper at back or in flue, its at the top previous owner slid fire bricks over the chimney slots for reduction,
Thank you, really hope I can get it going
Chloé
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On 3/12/2022 at 9:21 PM, Mark C. said:
Yes what size are the orfices now? natural gas has larger orfices -LPG should have considerable smaller orfice holes.
I get that its been convered but all 4 burners in one spot is a bit strange-We need to see the inside with door open as well.
You never mentioned anything about a damper-does it have one on top (I'm assuming its a updraft?)
The only downside with the hood so close is it will rust out sooner if it gets super hot and you could always have a stainless one made like i did as they never rust-make sure to cover your chimney cap when not in use for rain.
In terms of to small a hood that whole shed is just for this small kiln and your shed has a wall of windows on one side and one opens so ventaliation is looking great to me as long as you do not sit in there all closed up firing
So the issues can be
orfice size
burners to small-burner placement (all in one spot)
The stacking load of wares and bag walls
draft -layout inside to let gas flow thru load
damper issue-size of exit flue
explain in detail these issues as best you can to help us
Photos inside are a must
Hi, thank you!
Sorry will get back to you re orifice size, I don't know how to get to the burners to measure it.Has a damper ontop its a updraft, I'll attach a pictures, yes I have a storm cap which I put on when not firing. The shed is just for the kiln and the door stays open during the firing. The clesse changeover has a 37mbar restrictor on it - is that an issue? How do I calculate the mbar/bar I need? I think my plumber should have got me the 750mbar changeover?
Many thanks,
Chloé
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On 3/12/2022 at 6:42 PM, Bill Kielb said:
This will take some doing as 24kw should be enough to power this kiln reasonably insulated. It would be helpful to know the previous orifices, the current orifices before we start calculating to figure out what the issue could be. Interesting note is propane has a little more than twice the output of natural gas so your current orifices ought to be much smaller given they are designed for propane and also designed for a higher pressure.
Some observations: if this is going to be for reduction then the hood likely needs to be a bit higher so the reduction flames don’t contact the hood. I would like to see the hood wider as well to pick up the heat and additional fumes off the kiln. I would add a weather cap to the top of your stack as well for practical reasons. Finally, the height of the stack and diameter can help this kiln with proper airflow. So in the end after all the calculation (when we know the orifices) we may recommend several minor changes so the kiln breathes correctly, the actions of your damper are more manageable and we know we can maintain a 10:1 air / fuel ratio to get the most energy from your burners.
All this may take time to learn, so if rushed or commissioned you may want to fire in a kiln you are familiar until you dial in your own kiln.
Pictures of the inside, any other secondary air ports if on the side or bottom of the kiln and a picture of the overcut around the burners which is your secondary air port.
Hiya thank you!
The hood and bars between the kiln body came with the kiln/are part of the model. Will get back to you re orifice size - I dont know how to move the burners to measure the size will ask the plumber coming on Wednesday. And I dont have contact with the previous owner who converted it for previous orifice size I'm afraid.
I attach further pictures, the clesse changeover has a 37mbar restrictor on it - is that an issue? How do I calculate the mbar/bar I need?
I really appreciate your help thank you,
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I bought a J9 Laser Gas Kiln last year and finally got it installed, but I can't get it to reach above about 750˚C.
It rises over 6.5hrs to reach my maximum 35 Mbar at 570˚C and then crawls to 750˚C at 9hrs. I thought too much gas needed more air, so I've lowered the pressure, but the temperature quickly started to drop again.
The kiln was converted from Natural Gas to LPG; its internal dimensions are 52cmsq 80cm tall. With 4 burners, it runs off 4x47kg, which has a Clesse Automatic ChangeOver Kit has a hood and flue. It came with only a couple of pages in the manual, and the lady before me hadn't fired it before. Before her, the previous owner converted it to gas (and my plumber has checked it all over and connected it up). But we can't figure out why it's not reaching higher temperatures...
I have fired 3 different gas kilns regularly for the past 6 years, but all were installed by others, and I booked to use them, this is my first own gas kiln, and I was so excited to be self-sufficient. I have been using my previous firing schedules, but this is performing miles behind. Any help would be hugely appreciated. I have a deadline for an exhibition looming ever closer I'm sure I must be doing something wrong, I will attach pics of the set-up,
My plumber thinks that the interior needs replacing, it has cracked walls, and the front door padding has sagged, but it still does seal. Or he said he could look into making the burners orfice larger.
Laser Gas Kiln Help
in Equipment Use and Repair
Posted
It was a safety thing -- it (understandably!) didn't like the debris in the valves.
Unpacked the kiln this morning -- beautiful firing and in the shortest firing timeframe reflecting the original manual. So happy a potter all round!