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Kiln Conversion Updraft Downdraft Chimney?


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I guess I'll have to plead poverty.  Though I have to say, my squirrel cage blower was not whisper-silent either.  I found the noise irritating, but I put the vac in the laundry room and fed the hose out to the kiln, which was behind the laundry room.  Tolerable, at least.  An oil burner is not an intrinsically quiet device, unfortunately.  I imagine a forced air gas burner could be a lot less noisy, but I have no personal experience with forced air gas burners.  Mine were always naturally aspirated; in fact they were always home-made Bendel burners.  Another possibility for forced air is an old cannister vac.  With any of these cheap solutions, you should have a backup.  You don't want the vac to die half-way through the firing and have no way to finish.  You probably don't have to ask me how I know that.  Well, okay, I'll tell you-- my squirrel cage blower packed up mid-firing, which was when I discovered that a Shop-Vac would work.  It was fortunate that my big old surplus blower had to spill a lot of air too, so I had a way to do that.  At the time, my main consideration was that it was free.

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I started with forced air homemade burners in the 70's and quickly switched to venturi as power failures and noise plagued them and me. Now when the power goes off like yesterday during a bisque fire the kiln just kept going up.I love the natural gas deal.

I;m sure the forced air burners are more efficient and definitely burn hotter.

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Guest JBaymore

Among some I'm likely forgetting to write here, the main advantages of forced air ("power") burners over venturi-type aspirating burners or non-venturi "pipe"-type burners are that they:

 

1.)  are able to cause better mixing of the fuel and air before it actually reaches the wares in the kiln.  So you can get more even atmospheric conditions in the chamber.

 

2.)  are able to supply 100% or even 100%+ aeration of the fuel.  Even the most efficient and expensive casts of venturi's can entrain no more than about 70% primary air.  And those 'really good ones' are not the typical ones that potters tend to use (industrial units).

 

3.)  are able to remove the dependency of the entrainment of secondary air by the kiln system itself for complete combustion to occur. 

 

4.)  are able to somewhat isolate the kiln/burner system from being impacted a lot by variations in the weather and in the stacking of the load.

 

5.)  are able to reduce or remove the need for a contigious chimney on crossdraft or downdraft designs, thereby cutting construction complications and/or costs.

 

6.)  help to assure that no unintended fuel gas is left unburned when it exits the chamber.   

 

7.)  Produce a more uniform atmosphere in contact with the wares when the kiln is adjusted for "reduction" conditions.

 

8.) typically have better turn down ratios than atmospheric burners. (stability at lowest setting compared to highest setting).

 

 

best,

 

.......................john

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Can only remember one power outing in the 20 years being in the house but I will keep it in mind. There seem to be a few pc centrifugal fans that say output 28m3/h that could be a 12v backup with a battery. If it did go and I was near the end I could always try the venturi burner to hold it and wait or something.

 

Decided to go with that one you posted neil as only £8 postage and seems to look the part and spec right. Went over to the house and filed out the hole a little bigger. Luckily the left-hand propane to right hand thread nipple was the exact size for my gas tap :D you would have thought I planned it but I only dreamed that it would fit.

 

Now all I need is a 240 to 115 volt transformer and fitting to the end then it can get a real test.

 

med_gallery_23281_1039_1880388.jpg

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Other benefits of power burners:

-You can build them cheaper than buying Venturi burners as far as cost per BTU is concerned

- They can be modified for more or less power as needed by changing the orifice and doing so doesn't affect performance.

- A power burner will cost the same to build whether it's putting out 5,000btu or 500,000btu.

- You can use fewer burners.

- The cost savings in not having to build a tall chimney will offset the cost of the burner parts.

- In salt and soda kilns, power burners give better dispersal of the vapor.

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Little update as the parts have arrived. I went with the blower Neil had posted but being 115v I either had to buy a transformer and a fan controller or get a variable transformer. Luckily one day before I started searching somebody was selling a variable transformer they had never used, basically brand new but old. Cost about £40 with the postage so I think a good deal. 240 volt input and 0 - 265 output. 2.5 amp max load and the fan is only 0.5 amps I think. Didn't measure how much it was drawing yet.

 

Been testing and all seems to work, the fan comes on at ~30 volts and I haven't bothered going above 115 volts as I don't want to break it.

 

I wasn't really sure what to do with the earth from the plug as I only have two inputs so I lobbed it onto the transformer case. I can see an earth on the blower so shall be attaching it to there as well in the future.

 

med_gallery_23281_1039_118322.jpg

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Interesting idea lou, I think that would be a similar things to my transformer, at least in how they vary the voltage. I did have a look at some more basic dimmers but by the time I had bought a 240v to 115v transformer that was rated for the current and bought the switch I would have been around the same price point and this just seemed like the simpler option with less to break. Also it looks cool and I might have other uses for it later on.

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i like the looks of yours..... Retro

im not sure how your power system  comes into play,   all of forced air burners ive seen used the dimmer switch like in the link.     then mount in   http://www.lowes.com/pd_70972-223-B118A___?productId=3129409&pl=1&Ntt=electric+utilityu+box.    looking forward to see how yours works

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Well my foot is not broken but stuck on crutches for the next week or so :( not going to do a full firing till I am fixed but had a quick test with gas and air today. Having a little problem with fine tuning but a variable block on the air intake should solve that.

 

Went up to 3psi and no problems with blowing off the end.

https://instagram.com/p/BCbTtBzmGiz/

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NICE!!! You'l want to use a combination of dialing the air speed with the rheostat and blocking the air intake on the blower ( a magnetic business card works well for that). The rheostat will adjust air speed, the flap will adjust volume at any given speed. The speed adjustment comes in handy to keep from blowing the flame out at lower gas pressure. You'll likely never need to run it full speed, though.

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Strange, it should have worked but I did post from my mobile. Shouldn't have to download instagram but maybe I grabbed the wrong link.

 

Worked for me without installing anything......

 

Pleased to hear that your foot is not broken. Take it easy and follow doctor's orders.

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