Lp gas kiln stalls (Olympic Torchbearer)

[Pklove]

I have an Olympic Torchbearer 2827g set up for propane.  It’s the older version with six small burners. The manual for this is…badly written (I deleted a lot of words here.)

I have a 250# tank, a regulator rated for 11” water column, orifaces drilled to #40, as per the manual (I’ve also tried #50 and #60.)  No leaks, ample pipe size, full tank, air wide open.  I am at sea level, I swim in Lake Michigan daily and walk there.

But it stalls on me, constantly.  It’s stalling right now.

What am I missing here?

So far no help of use from Olympic, I’d be fine if they said “oh, that burner set up never worked, scrap it and get (fill in the blank.)”

I got back into pottery for stress reduction…not this (again, fill in the blank.)

Any help appreciated.

 

 

[neilestrick]

What's the gas set at? What temp it is stalling at? How open is the flue? What size shelves are you using, and how are they set up in the kiln?

These kilns have always been problematic.  Do some searching here on the forum and you'll find a number of solutions. Sometimes people have trouble due to turning the gas up too high. Others say that there has to be a shelf an couple inches below the lid.T he best solution for this type of kiln is THIS, however that may be more work than you want to do.

[Pklove]

Thanks for the response.  
 

The top shelf is over an inch below the top.  Dampers are set to keep the atmosphere neutral, no reduction stink. The stack is loose, no plate shelves and open in the middle.  A good two inches from the walls, plenty of room to breathe. Gas is not full bore, about 75% and the flame is blue at the burner tips . 
It climbs great to about 1700 F (500 degrees an hour) and then it struggles and craps out at 1800.

I’ll check out the link, I’m guessing that you are thinking “convert it to a downdraft.”  Which is what I’m thinking.  Which I’ll probably do anyways.  I just want to fire, I’ve got a ridiculous amount of work made already.  Soon I will not be able to get into the studio without causing an avalanche.

The thing is rated to cone 10, and I’m only shooting for 6.  So I figured that it would be easy peasey.  Ha.

Time to start digging in the archive.

(That is hilarious, most of the replies are from you.  You must be shaking your head thinking “another one.”)

Edited July 19, 2023 by Pklove

[Babs]

Are you overdoing it re trying to get zero reduction? All the heat at the business end of firing going up the chimney? May be need to do a bit of playing with the damper to stop heat loss

[Pklove]

The Olympic torchbearer doesn’t have a chimney.  It is basically an octagon (like a Skutt) where the burners come in through the floor and exit is through a hole in the lid.  
I got it because it is “portable” and I like the idea of being able to move it for pop up workshops.

[neilestrick]

Have you tried backing off on everything? Those kilns don't really breathe very well, so they're easy to overpower. If the air is wide open, try closing it down and reducing the gas accordingly to get the atmosphere you want. 

[Mark C.]

To much gas is often whats going on. Open the air flaps on the burner all the way if there are any. The only adjustment I would do is the exit shelve on top.-You need a digital pyrometer to see what really going on. The 6 burners are better than the 4 burners. 6 burners is a lot for that size kilns so turn the gas down. When the climb is good leave it alone

Edited July 20, 2023 by Mark C.

[Bill Kielb]

20 hours ago, Pklove said:

orifaces drilled to #40, as per the manual (I’ve also tried #50 and #60

#40 orifices are larger than # 50 and # 60. With #40’s and a blue flame you max out at about 37000 btu per burner, which would be about 225000 btu for all six. That’s a lot of energy for a small kiln.

So stalling can be because of atmosphere but is often because of damper adjustment. Especially this kiln. Really small adjustments are needed to maximize the energy in the kiln and just keep it out of reduction. When I say really sensitive, I mean 1/32” or less to trap as much heat as practical while just staying out of reduction.

 I would also double check sizing and pressure - #50 orifices net about 34000 btu per burner, #60, 11,000 btu pr burner so a huge disparity there so likely some misunderstanding.

[Pklove]

I’m beginning to get the impression that this is the Yugo of kilns.  

I now have drill bits for 40, 5/64, 50, and 60…I’m getting seriously good at that.  No two sources have said the same thing.

It doesn’t help that the manual is so horribly done and that Olympic is …well…not in the running for when I upgrade.

I would prefer if they just said “that model is obsolete, you need a new burner system” instead of wasting my time.

Edited July 19, 2023 by Pklove

[Bill Kielb]

Looks like #40 is more correct. Their new kilns are 240000 btu and …… my mistake #40 might be a bit large in the 6 burner so #50 gets you closer. Decent table here:http://www.davegardner.org/images/GasInfo/OrificeTable.pdf If you are lucky it is on the kiln tag.

Looks like you want to max out at 240,000 btu by todays standards which means #50 or slightly larger, closer to # 48. If you drill them yourself and don’t leave the conical approach in, they will not perform quite as well as if manufactured.  If you have #40’s in there and decent blue flame then I would definitely work the damper. Small (very small) adjustments will have very dramatic effects once you  get closer to reduction.  You. Want to keep as much heat in as practical, just short of reducing. This changes as the fire progresses and  as the operating pressure increases as well.

updrafts can be tricky (especially a small kiln) but folks have fired them for years so they can be mastered. It does take a reasonable amount of patience though. It would be great if you could watch someone fire successfully. When we do this usually folks observing see a few things that they never would have realized. Demonstrating the dramatic affect the damper has often enlightens may so maybe seeing is believing I guess.

zehat are you using as a damper?

[Pklove]

Olympic recommends 5/64ths.  ( and that just made everyone who uses the metric system make a  sour milk face.)

I generally think that failure is okay, it’s how you learn.  And a kiln takes a dozen times to fire before you know what you’re doing.  I learned how to fire forced air alpine’s originally. And that took time.  After a certain amount of time I could hear when there was a problem and smell when I needed to make changes.

I would love to talk to some who knows this bugger.  I have a sneaking suspicion that the stack is very critical.  But unfortunately the manual is…bad.

[Babs]

14 hours ago, Pklove said:

The Olympic torchbearer doesn’t have a chimney.  It is basically an octagon (like a Skutt) where the burners come in through the floor and exit is through a hole in the lid.  
I got it because it is “portable” and I like the idea of being able to move it for pop up workshops.

Yes, wrong word, may need to slide brick over part of top hole to reduce the suck out of hole,  alonG with playing down the gas

[Mark C.]

(Olympic recommends 5/64ths.) In Michigan these bits are common at any hardware store.

I have been a round a few of these and even converted one to a =downdraft salt kiln (short life). Start slow with gas and as Bill said small adjustments on the flue are critical .6 burners should fire this easy to cone 10.

Digital pyro is also key to use.

Edited July 20, 2023 by Mark C.

[Pklove]

Olympic recommends 5/64ths.  ( and that just made everyone who uses the metric system make a  sour milk face.)

I generally think that failure is okay, it’s how you learn.  And a kiln takes a dozen times to fire before you know what you’re doing.  I learned how to fire forced air alpine’s originally. And that took time.  After a certain amount of time I could hear when there was a problem and smell when I needed to make changes.

I would love to talk to some who knows this bugger.  I have a sneaking suspicion that the stack is very critical.  But unfortunately the manual is…bad.