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Converting Alpine EF-4 208v 3ph kiln to 240v

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I have been looking around on the web for answers to this question and this seems to be the best place to try and see if anyone has experience with this.

I got a great deal on a couple of Alpine EF-4 kilns recently ($200 for 2) and at the time knew that one was 208v 3 phase but thought one had been converted to 240v. Both kilns seem to be in great shape and so I figured that I could figure out how to convert the other 240v 1 phase... Both kilns were 208 3 phase...

I have e-mailed back and forth with Joe from Alpine multiple times and have been able to get the wiring schematics for both the 208v 3 phase kilns as well as the 220v 1 phase and am asking for the 240v diagrams now. And Joe has confirmed that the conversion from 208 to 240 can be done. I was just wondering if anyone had worked with these EF-4 kilns before and if anyone had any advise on the conversion.  I have attached a few pictures of the kilns and the wiring diagrams I have received for reference. 

Any idea's on where to start the conversion or sourcing of parts would be appreciated too.

 

Kilns.png

220v1ph.PDF 208v3ph.PDF

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While not having converted those specifically any that I have converted I have changed them to automatic operation during the conversion and scrapped the prior control methodology and relays. They look small so my inclination would be to hang a Bartlett controller on them rewire  with 240 V elements as balanced as practical using new compatible relays available for most of today’s kilns.

I don’t think I would use much of the control methodology presently installed. At least that is my first impression without seeing what is in them.. the 18kw one ought to be a bit tough electrically. 75 amps or greater at 240v single phase.

Edited by Bill Kielb

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Ok, yeah that makes sense about replacing the elements/wiring. Attached is a picture of the wiring of the 1997 kiln. There are a few components that I am not sure are depicted on the wiring diagrams sent from Alpine so I was having trouble piecing things together.

Also when I talked to Joe from Alpine he stated:

Quote

We noticed both name tags say 208v, 3 phase, although the amperage and kw stamped on the
name tags do not jive with each other or our specifications.

An EF-4, 208v, 3 phase, 28 amps, 10 kw
     EF-4, 208v, 1 phase, 48 amps, 10 kw
     EF-4, 220v, 3 phase, 24 amps, 10 kw
     EF-4, 220v, 1 phase, 45.5 amps, 10 kw

So I am not sure if I am just "Lucky" to get a 18kw, or what is going on there...

Wiring1.png

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Most of what I see is three phase stuff with the exception of the machine tool transformer that probably supplies  120v for control operation.  Nice three phase mercury relay though! I would definitely strip them and rewire using today’s relays and a today style control while maintaining proper electrical safety. My guess is the 18kw nameplate is correct so, with the size these are which appears small, I would also give thought to derating them If I could convince myself they are overpowered for pottery kilns. Doing this would definitely consume some time and calculating and likely would be much more difficult than following the wiring diagrams provided.

can you post the diagrams? I don’t want to sound hopeless. For me it would be a project I enjoy actually.

Edited by Bill Kielb

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So looking at these diagrams  it is a  straight up conversion for a 10kw kiln from 208v  3ph. to 240 v. 1ph. Much of the wiring gets replaced, the devices get replaced, 3 pole contactor with higher current two pole, etc.... and the controller is a 0-2400 degree what appears to be a soak and hold control with no way to know if segments can be programmed etc....

so my inclination is strip it out of its controls and install new with a new kiln operating controller and 240v elements. Just going through this in my head, each pair of elements can be on a single relay so three typical relays say 15.00 each or 45.00. New high temp wire #12 gauge for each circuit, A 60 amp breaker to land all the circuits on and protect the machine. Plus a new Bartlett controller 300.00 and some wiring and set them as single zone.

so I am going to say 450.00 not including the elements as a wild guess for the 10kw DIY.

Basically I would look to change it to be pretty much like the cone art diagram below.
 

As far as the 18kw, it’s just a lot of energy at 240 volts single phase so the rewire would likely be something very different or if the same physical size I would lean towards making them both 10 KW.

C88B6B42-2B4C-43F0-86AF-758B8587A066.jpeg

Edited by Bill Kielb

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Would it be worth trying to reuse the existing control equipment that is currently attached to the kins? They both have Chromalox 2104, as well as Fire Right Jr.

Also just to answer the Size question these 2 kilns are exactly the same size. Not sure why 1 is 10kw and 1 is 18kw. But I would plan to convert both to 10kw.

Chromalax.png

FireRight.png

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15 minutes ago, HamiltonStoneware said:

Would it be worth trying to reuse the existing control equipment that is currently attached to the kins? They both have Chromalox 2104, as well as Fire Right Jr.

Also just to answer the Size question these 2 kilns are exactly the same size. Not sure why 1 is 10kw and 1 is 18kw. But I would plan to convert both to 10kw.

Chromalax.png

FireRight.png

Nice old controls. I would replace for convenience but it appears you can program these. Maybe a bit difficult but doable. With that in mind then I would maybe buy one large 60 amp contactor, new breaker or you could cartridge fuse as they did, new elements, new rewire to the contactor and operate that way. So 100.00- 200.00 in parts (not including elements) but a bit more difficult to program.

I think I would go for full upgrade and potentially keep the chromalox as a  redundant high limit though.

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@HamiltonStoneware Yes, the current equipment will work just fine. To continue using it, you'll need to change out the main relay to one that can handle the higher amperage from being on single phase. You may also need to change the fuses so they can handle the increased amperage. You'll have to change the power distribution since you'll only have 2 hots instead of 3. Make sure the wires are big enough to handle the increased amperage. And you'll have to change the elements to go from 208 volts to 240 volts.

The Chromalox is just being used as a high temp shutoff. The FireRight Jr will control rate of climb. The downside of the existing controls is that they don't measure heat work, just temperature. You'll need to make sure you're programming the peak temp correctly to achieve the cone you want at the speed you're firing. The Chromalox is a general purpose heating controller- it's not designed specifically for pottery kilns. As such, it's got a ton of programmable parameters in it that you won't need, and adjusting the peak shutoff temperature is a pain. If I remember correctly there's a point where you have to scroll through something like 16 other parameters to get to the one you need. So if you bisque and glaze at different temps, it can be a bit of a hassle to make the changes. But you'll probably get used to it after a few uses. Together with the FireRight Jr you've got a perfectly functional system, it's just not easy to use compared to modern controllers. I think there's a way to put the FireRight on 100% power and then use the Chromalox for custom firing schedules.

Switching to a proper kiln controller would require a lot more rewiring and parts, and cutting the panel to fit the new controller since it's not the same size as the old ones, but it would be easier to use. It's something you could always do later, though, after trying out the current system for a while to see if you get the hang of it.

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7 hours ago, HamiltonStoneware said:

Would it be worth trying to reuse the existing control equipment that is currently attached to the kins? They both have Chromalox 2104, as well as Fire Right Jr.

Chromalax.png

 

I did check out the chromalox 2104 control and it is a full feature PID temperature controller that can be programmed. It is very complicated if you are not used to these things but it does have a learn function. So to that end two things struck me.
 

One - you can come pretty close to getting your cones to tip when you want if you follow the schedules that are in the Bartlett controller. The important part is the last 250 degrees of the firing so if you use their rate for this final segment you should be close and can tweak from there for a bisque or glaze fire. And two- you would be able to put these programs in segmented memory and just run them as you need.

the setup and learning curve could be extremely difficult if you are not familiar but once done, you pretty much have two kilns with easy to use cone fire programs that really could be set at 100% power as far as the FireRight jr is concerned. The 2104  allows you to build slow preheat segments etc.... and it does have a self learning function so it is doable with some effort.

good luck !

5860E198-8B0F-40FC-B710-32E072804616.jpeg

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