Need advice/suggestions on a COMPLETE retrofit of older L&L J2927 kiln

[starrs_ridge]

I have acquired an old (1996) L&L kiln. It is 29" w by 27" deep (10cf) with three sections. It is a single phase, 208v, 60amp setup. (Model J2927)

My goal is to completely replace all the elements, thermocouples, controller, etc with all-new parts. Essentially, I am only going to keep the bricks, and the aluminum shell, which are in good shape.

I know that "hotkilns" dot com has all the OEM L&L parts I would need, (and I will probably need to go there for the elements) but I would like to know if anyone else has good suggestions for starting from scratch when it comes to all the electrics and controls for a kiln. Budget is a minor consideration, but at the same time, this does not need to be high-end. Just a modern, electronic controller solution with new electrics all around.

I want to make this a 240v setup, since 208v is not standard in residential electric service.

Any and all suggestions are welcome -- thanks!

[neilestrick]

You'll want to get the elements and thermocouples from L&L. Relays you can find online for 1/3 of the price, like HERE. If you're going to replace the wiring,  getting a wiring harness from L&L would be the fastest way to go, but you can buy  insulated wires, controller wiring, and terminals ends by the foot online and save some money there. Search SRML wire for insulated wire, I buy HERE. For jumper cords make sure you get cords rated for 105C/220F- you can buy SEOOW cable from McMaster and put your own plug ends on it. You can use SEOOW for the power cord, too. You can get insulating sleeving on Amazon. For the element blocks, use stainless steel hardware from the hardware store. You don't have to use the hex head bolts since they're hard to find, just use 10-24 panhead bolts.

Make sure all your wires are the appropriate gauge for what you're doing.

Get a Bartlett Genesis 2.0 controller. There may or may not be deals out there, just order from Bartlett if not.

[starrs_ridge]

Excellent advice, Neil, exactly the sort of input I was looking for -- thanks!

[starrs_ridge]

20 hours ago, neilestrick said:

You'll want to get the elements and thermocouples from L&L. Relays you can find online for 1/3 of the price, like HERE. If you're going to replace the wiring,  getting a wiring harness from L&L would be the fastest way to go, but you can buy  insulated wires, controller wiring, and terminals ends by the foot online and save some money there. Search SRML wire for insulated wire, I buy HERE. For jumper cords make sure you get cords rated for 105C/220F- you can buy SEOOW cable from McMaster and put your own plug ends on it. You can use SEOOW for the power cord, too. You can get insulating sleeving on Amazon. For the element blocks, use stainless steel hardware from the hardware store. You don't have to use the hex head bolts since they're hard to find, just use 10-24 panhead bolts.

Make sure all your wires are the appropriate gauge for what you're doing.

Get a Bartlett Genesis 2.0 controller. There may or may not be deals out there, just order from Bartlett if not.

Follow-up questions:

The new controller (Bartlett Genesis 2.0) would have to be the complete controller/element assembly (not just the panel), correct? By which I mean: there are two "boxes:" the one with the controller panel, and the box which it mounts to (the element/thermocouple wiring box). In other words, I cannot re-use the existing element boxes/connectors (this is a 3-zone, three-jumper setup. Three sections on the J2927 - see picture #1). 

These existing element boxes do NOT have thermocouples -- only the kiln sitter has a thermocouple (in the center section of the three sections). The bricks in the top and bottom sections have a peep hole, however, I THINK that I would need to replace the bricks in each section (where the element connections currently exist) with NEW brick sections that have proper holes for both the connection AND a thermocouple, yes? (See picture #2)

The old analog control box has the Robert Shaw Infinity knobs and the old-style fuses -- and because that is all 208v, it has to go completely.

Summary: Do I need new brick sections if upgrading to modern elements/thermocouples? And, do I need to get an all-new element connection box PLUS the controller box (such as the example in picture #3)

Thanks again for the assistance!

[neilestrick]

4 hours ago, starrs_ridge said:

The new controller (Bartlett Genesis 2.0) would have to be the complete controller/element assembly (not just the panel), correct?

You may be able to retrofit the old box with the new controller system if it's big enough to hold all the parts. Look at the current Jupiter models- the control box mounts on top of the element boxes, and connects with jumper cords. L&L recently switched to a much larger control box, but the old box was a lot smaller and everything fit fine. You'll need to fit 3 relays, a transformer, and a fuse. Otherwise you can buy a bigger box and either mount it to the element boxes or wall mount it and use longer jumper cords. If you're going with 3 zones, you'll need 3 thermocouples, and you can drill holes for those in the kiln body.

Any holes in the control box that wires go through will need some sort of strain relief, and everything must be grounded. If you need advice as you move forward, post lots of pictures here and we can review it.

 

[oldlady]

if i read it right, you plan to use the present hole that is part of the kiln sitter for a thermocouple in the center section and use the current peep holes for thermocouples in the top and bottom rings?   sounds sensible to me.

[Dick White]

11 hours ago, starrs_ridge said:

Follow-up questions:

Summary: Do I need new brick sections if upgrading to modern elements/thermocouples?

As noted by Neil above, you can drill new holes where you want the thermcouples to go. Measure carefully so you know where to start the hole through the metal shell to ensure it comes out the other side in the right place. Regarding new bricks, be aware that L&L has changed the size of the hard ceramic element holders several times over the years. Your kiln from 1996 has the original smallest size channels and thus can only hold the smallest diameter elements. When you order from L&L, they will ask you the serial number (which is the manufacturing date) so that they can send the proper size.

Also, regarding the reuse of the top-mounted control box with the Robert Shaw switches, yes that could possibly be used - if you are facile with basic metal working. The Bartlett controllers (either the V6-CF or Genesis) require a rectangular hole through the face of the control box so that the faceplate of the controller is on the outside while the circuit board and connectors are on the inside. You'll have to cut that hole yourself - after ensuring there is enough space inside for the controller, transformer, fuse, 3 relays, and the existing three 250 volt 25 amp sockets for the jumper wires to each kiln section. When I was rebuilding my J230 of a similar vintage, I didn't think I could cram all that in, so I built a new box with a metal enclosure box I got from the big river in South America dot com. Even then, there was some cutting and drilling required.

dw

[starrs_ridge]

Thanks for all the advice and ideas to Neil and everyone else. I will definitely keep updates with photos as I go.

I will start with the control box retrofit to make sure that I can use the new Genesis controller mounted on the old box -- along with the new relays and transformers. With any luck, this will be ready to go by winter, when my wife plans to be spending more time at the wheel and will have pieces ready to fire.

Thanks again!

[starrs_ridge]

21 hours ago, neilestrick said:

You'll need to fit 3 relays, a transformer, and a fuse.

 

The Bartlett Genesis 2.0 is on order.

I have these lined up next:

Three Relays:  Schneider Electric 12VDC, 6-Pin Bottom Flange, Din Rail Enclosed Power Relay; Electrical Connection: 1/4" Tab Terminal (92S7D22D-12D) as pictured below.

Transformer: DP-241-5-24, Power Transformer, Laminated, Pri: Dual 115/230VAC, Sec: 24VCT 0.5A; Center Tap; Power - Max 12VA; Mounting Type:Chassis Mount (see picture)

Fuse:  What amp rating/form factor for the fuse? Does the Bartlett documentation cover the schematics for wiring and components? Or am I on my own for that?

 

Thanks again.

 

[PeterH]

Are you going to fit a current sensor?

[neilestrick]

16 minutes ago, starrs_ridge said:

Fuse:  What amp rating/form factor for the fuse?

A standard AGC fuse and holder will work fine, 1/2 amp.

HERE is a wiring diagram for an L&L Easy Fire kiln. You may or may not want to include an on/off toggle like they do. Everything would be the same except the output from the relays will go to the outlets on your control box that the jumper cords plug into.

[starrs_ridge]

11 minutes ago, neilestrick said:

HERE is a wiring diagram for an L&L Easy Fire kiln.

Yep, this is a perfect wiring diagram. Will do very nicely. Thanks!

[starrs_ridge]

14 minutes ago, PeterH said:

Are you going to fit a current sensor?

I had not thought of that -- do you mean for the incoming 240v current? Or at some other point in the circuitry?

[PeterH]

48 minutes ago, starrs_ridge said:

I had not thought of that -- do you mean for the incoming 240v current? Or at some other point in the circuitry?

From https://tinyurl.com/jtcjby88

We also purchased this $34 amperage detector from Bartlett which is a tiny circuit board you connect to the kiln controller and has two white leads connecting to a ferrite ring.

You thread one 220 volt power lines from each relay to the heating elements through the ferrite ring, which measures the power being consumed.  This allows the controller to compare your current power draw to the original power draw when you installed the elements or in our case when we installed the controller.

The controller tests the elements for about 60 seconds prior to each firing.  A decline in amperage used is charted to determine your element aging and any sudden decline indicates the failure of an element.

I think it also does other helpful things, like reporting the power consumed (and its cost). Don't know if it can detect things like stuck relays in real time.

Edited August 22, 2022 by PeterH

[starrs_ridge]

Peter:

Great idea! I have prior experience with current detectors in other applications, and what you describe makes sense. And it's very practical!

Also: I definitely have an interest in tracking power consumption. I have a very good home automation hub which is able to track any wifi-enabled current sensor which is placed in-line at the incoming AC source. You have made me think about this as an important way to track the cost of firing the kiln.

Thanks again!

[Bill Kielb]

14 hours ago, starrs_ridge said:

Transformer: DP-241-5-24, Power Transformer, Laminated, Pri: Dual 115/230VAC, Sec: 24VCT 0.5A; Center Tap; Power - Max 12VA; Mounting Type:Chassis Mount (see picture)

Small signal transformer, stamped 5 va? Looks too small, I would double check. 3  relays (~2W each) plus the electronics. I think worth double checking, picture is stamped 5va.

[starrs_ridge]

3 hours ago, Bill Kielb said:

Small signal transformer, stamped 5 va? Looks too small, I

You are correct, I need a 12va transformer -- I grabbed the wrong image here, sorry.  But thanks for pointing that out.

[neilestrick]

5 hours ago, starrs_ridge said:

You are correct, I need a 12va transformer -- I grabbed the wrong image here, sorry.  But thanks for pointing that out.

You need a 24 volt transformer. The controller runs on 24 volts, but has 12 volt outputs.

[Bill Kielb]

1 hour ago, neilestrick said:

You need a 24 volt transformer. The controller runs on 24 volts, but has 12 volt outputs.

I think he is good 24v ct so 12 and 24VAC.  His original picture is 5 va (5 watts) too small. 12 va (12 watts) sounds right

Edited August 23, 2022 by Bill Kielb

[neilestrick]

1 hour ago, Bill Kielb said:

I think he is good 24v ct so 12 and 24VAC.  His original picture is 5 va (5 watts) too small. 12 va (12 watts) sounds right

Sorry I misread that. The Genesis manual says you need at least 6va to run 3 relays.

[Bill Kielb]

1 minute ago, neilestrick said:

The Genesis manual says you need at least 6va to run 3 relays.

Makes sense, last I looked at the relays just under 2 watts each.

[starrs_ridge]

Looking at the wiring diagram, the Transformer specs are below:

TRANSFORMER 115/230 VAC - 50/60 HZ (PRI), 24 VCT (SEC) - 12 VA, L-G-TR24/00

[Bill Kielb]

1 hour ago, starrs_ridge said:

TRANSFORMER 115/230 VAC - 50/60 HZ (PRI), 24 VCT (SEC) - 12 VA, L-G-TR24/00

 

Specs are good! Funny the drawing shows off-center tap. I am guessing it’s just the drawing.

[starrs_ridge]

Update: The transformer and relays are on order, as is the Genesis 2.0

Next: I will be ordering the new thermocouples and elements from L&L.

Question: the wiring diagram which Neil linked to as an example is for an Easy Fire kiln -- which has 2 elements per ring. The J2927 has 3 elements per ring (9 elements total). Does that even matter? I don't think it does, since the elements are wired in series back to the power, and it's all about the total load -- not the number of connections.

Am I correct here?

For reference, here is a snip from the diagram with the 2-element connection:

[Dick White]

Gearing up the Ohm's Law calculator -  you want the total amperage of the kiln to remain 60 amps but at 240V vs. the original 208V. There are 3 sections, so each will pull 20 amps. Using the calculator to convert that to watts and resistance, gives us 4800 watts and aggregate resistance of 12 ohms per section. If the 3 elements in each section are wired in series, they need to be 4 ohms per element. When you order the elements from L&L, ask/confirm the design resistance of each element and the connection requirements (parallel vs. series) for the elements they are providing. It is possible they have a different plan now than in 1996.