Dick White

Further to Min's answers to your stated questions -
1. Don't buy a hydrometer. Contrary to popular wisdom, hydrometers are useless. Do a forum search for some of the other threads where we have discussed using a 10 or 100ml syringe and a digital scale to accurately measure specific gravity.
2. Not glazing the interior of a pot increases the risk that the pot itself will fail due to unequal tension/compression of only one side of the ceramic being glazed.
3. What Min said.

Further to Min's answers to your stated questions -
1. Don't buy a hydrometer. Contrary to popular wisdom, hydrometers are useless. Do a forum search for some of the other threads where we have discussed using a 10 or 100ml syringe and a digital scale to accurately measure specific gravity.
2. Not glazing the interior of a pot increases the risk that the pot itself will fail due to unequal tension/compression of only one side of the ceramic being glazed.
3. What Min said.

The picture of the electrical rating plate is a bit fuzzy, but looks to me like 24 amps. Thus, in the US national electric code, that would require a dedicated heavy duty 30 amp circuit, not an ordinary household plug. I don't know about the Aussie electric code, but it is probably similar. The circuit requirement includes not just the plug and receptacle, but the wiring back to the mains and the breaker. Since you will probably need an electrician to install the special circuit, you have a choice to hardwire it or have the electrician install an appropriate plug on the power cord.

Single firing is usually no different EXCEPT that it is really just a bisque firing to glaze temperature. The raw clay body needs to be fired slowly during the early stages so that it does not explode or fracture. Bisque schedules usually provide for this; glaze schedules for previously bisqued ware just charge ahead, damn the torpedoes. The glaze work itself is just fine, it's the clay body that you need to worry about.

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.

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.

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

My understanding of the physics (fluid dynamics) behind the downdraft vent is that the box under the kiln (L&L calls it the bypass collection box, Skutt calls it the plenum cup) has an opening on the opposite side from the hose connection so that the fan at the output on the far end of the system can pull a significant volume of room air through the box and thus create a venturi effect to draw the kiln fumes down through the holes in the base of the kiln. The L&L collection box has an adjustable "sliding valve" to regulate the amount of room air drawn through the box (thus adjusting the venturi suction across the holes in the kiln base) while the Skutt plenum cup just has a hole. This flow of room air also serves to cool whatever fumes are being drawn out of the kiln and up through the fan. The system does not apply direct suction to the holes in the kiln.
Because air flows seek the path of least resistance, the hole in the pipe of your vent will both increase total air flow at the fan and reduce suction at the base of the kiln when everything is in good condition. However, it introduces the necessary cooler room air at some distance after the fumes leave the kiln. Also, your design with the fan in the middle of the duct run provides the appropriate negative pressure from the kiln to the fan, but applies positive pressure after the fan, blowing the exhaust into the stove hood in hopes that it will be picked up. As Bill notes, this may not work, but also as the duct work corrodes over time (it will, count on it), the positive pressure will blow the stinkies back into the room long before they come out by the stove hood. The design of the Skutt and L&L systems places the fan right on the outside wall of the room so that the whole system remains under negative pressure until being exhausted to the outside. Then, any minor leakage in the duct work will draw air in, not push the fumes out.

My understanding of the physics (fluid dynamics) behind the downdraft vent is that the box under the kiln (L&L calls it the bypass collection box, Skutt calls it the plenum cup) has an opening on the opposite side from the hose connection so that the fan at the output on the far end of the system can pull a significant volume of room air through the box and thus create a venturi effect to draw the kiln fumes down through the holes in the base of the kiln. The L&L collection box has an adjustable "sliding valve" to regulate the amount of room air drawn through the box (thus adjusting the venturi suction across the holes in the kiln base) while the Skutt plenum cup just has a hole. This flow of room air also serves to cool whatever fumes are being drawn out of the kiln and up through the fan. The system does not apply direct suction to the holes in the kiln.
Because air flows seek the path of least resistance, the hole in the pipe of your vent will both increase total air flow at the fan and reduce suction at the base of the kiln when everything is in good condition. However, it introduces the necessary cooler room air at some distance after the fumes leave the kiln. Also, your design with the fan in the middle of the duct run provides the appropriate negative pressure from the kiln to the fan, but applies positive pressure after the fan, blowing the exhaust into the stove hood in hopes that it will be picked up. As Bill notes, this may not work, but also as the duct work corrodes over time (it will, count on it), the positive pressure will blow the stinkies back into the room long before they come out by the stove hood. The design of the Skutt and L&L systems places the fan right on the outside wall of the room so that the whole system remains under negative pressure until being exhausted to the outside. Then, any minor leakage in the duct work will draw air in, not push the fumes out.

My understanding of the physics (fluid dynamics) behind the downdraft vent is that the box under the kiln (L&L calls it the bypass collection box, Skutt calls it the plenum cup) has an opening on the opposite side from the hose connection so that the fan at the output on the far end of the system can pull a significant volume of room air through the box and thus create a venturi effect to draw the kiln fumes down through the holes in the base of the kiln. The L&L collection box has an adjustable "sliding valve" to regulate the amount of room air drawn through the box (thus adjusting the venturi suction across the holes in the kiln base) while the Skutt plenum cup just has a hole. This flow of room air also serves to cool whatever fumes are being drawn out of the kiln and up through the fan. The system does not apply direct suction to the holes in the kiln.
Because air flows seek the path of least resistance, the hole in the pipe of your vent will both increase total air flow at the fan and reduce suction at the base of the kiln when everything is in good condition. However, it introduces the necessary cooler room air at some distance after the fumes leave the kiln. Also, your design with the fan in the middle of the duct run provides the appropriate negative pressure from the kiln to the fan, but applies positive pressure after the fan, blowing the exhaust into the stove hood in hopes that it will be picked up. As Bill notes, this may not work, but also as the duct work corrodes over time (it will, count on it), the positive pressure will blow the stinkies back into the room long before they come out by the stove hood. The design of the Skutt and L&L systems places the fan right on the outside wall of the room so that the whole system remains under negative pressure until being exhausted to the outside. Then, any minor leakage in the duct work will draw air in, not push the fumes out.

I've never done it, but some things to consider - The preheat segment on a Bartlett controller is 180-200F, depending on the age of the controller (some of the older models I have preheat at 200F, the newer ones at 180F). If 240F is right, why does Bartlett keep it lower than boiling? With an electric kiln w/ controller, there may be some thermocouple offset programmed in, so the apparent temperature showing on the screen may not be the actual temperature of the atmosphere in the kiln? It takes time for the temperature to penetrate the clay body, so the surface may be already dry and hotter than the interior which is still cool enough that it doesn't turn to steam? A principle of phase change is that evaporation leaves the surface from which it evaporated cooler, so 240F may be the perfect atmospheric temperature to balance the evaporating moisture and surface temperature of the ware?
dw

Well, actually, it can be kludged to do that. I didn't feel like paying $180 for the feature, so I built one with $20 of parts to control the shared vent for both my bigger kilns. The wire from output 4 triggers a standard relay that turns on the vent power cord. I ran the wires from both controllers' output 4 to the relay, so now whichever kiln turns on first starts the vent fan and whichever kiln turns off last stops the vent fan. But one must be adventuresome to open the box and do that.
dw

The elements of the US version are all the same, 11.4 ohms. However, because the middle and bottom elements are wired in parallel, for a service person taking a resistance reading across either of these two with everything in situ will include the other, yielding a reading of half, or 5.7 ohms.

The elements of the US version are all the same, 11.4 ohms. However, because the middle and bottom elements are wired in parallel, for a service person taking a resistance reading across either of these two with everything in situ will include the other, yielding a reading of half, or 5.7 ohms.

According to Wikipedia, the standard mains voltage in Taiwan is 110V, or 220V when measured across both poles of the split-phase service. The US version of the Skutt 714 is designed for 120V mains. Something to note about the design of the 714 is that it is actually two stacked but electrically separate 120V kilns. It requires a 4-wire (two 120V hots, a shared neutral, and ground) NEMA 14-30 plug.  One 120V side of the line powers the top element and the other 120V side powers the middle and bottom elements (which are wired in parallel). It is designated as either 120/208V because, in the US, 208V service in commercial locations is also 120V from either line to neutral/ground. So what does this mean for Didiho? In the best of circumstances, the kiln when used in Taiwan will have about 10% less heating power than in the US simply because the standard mains voltage is 110V vs 120V. If the Diag function (which measures across both lines without regard to the neutral) is getting only 217V with no load and 207V under load, that suggests the power supply from the utility is lagging or the household usage is overloading its capacity. This yields a performance loss of at least 20% from the nominal US design.  Further, as the elements wear through usage, the heating power will decrease, until at some point it simple can't finish the job and the dreaded E-1 error appears. You can't fix the utility supply problem, but you can check whether the elements are worn past their prime. The three elements for the 714 are all the same, with resistance specified as 11.4 ohms. You can use a digital multimeter to test the resistance of each element. If the resistance measures more than 12.5 ohms, the element is worn out and should be replaced.

Nice discussion on copper/tin interactions in
Copper Red Glazes https://digitalfire.com/article/copper+red+glazes
Well worth reading the whole page, but the highlight is perhaps
Sn does a couple things. First it improves the solubility of Cu. Metals, per se, aren't really very soluble in glaze and if you can't get the metal dissolved, it can't very well be precipitated in any organized fashion. Second, on cooling, Cu tends to attract Sn atoms from the glaze. These atoms sort of "coat" the crystals as they are developed and thus serves to control their size by limiting the attachment of further Cu atoms to the crystal. This behavior is that of a protective colloid and it is of great advantage. Because if the crystals get big, the glaze turns "livery" looking, and the doughnut remains elusive. Third, to the extent that Sn has limited solubility in SiO2 or B2O3 based glassy material, it probably also serves to provide nuclei on which the coloring crystals can grow.
Tin oxide is added to all practical non-lead Cu red glazes in amount way beyond what's necessary to promote good solution of Cu in the glaze - many compositions contain up to 4-wt%. Of course, if there's too much tin it doesn't all dissolve -- causing opacity. This may or may not be desirable.
 
Also of possible interest
The Dual Mechanisms of Tin Oxide in Copper Red Glazes https://glazy.org/posts/168150

Ask your building supervisor, and particularly, the electrician to get out their code book and look first in Article 100 (Definitions) where continuous duty is defined as 3 hours or more at full load (i.e., your kiln on high as it finishes the firing), and then at Article 210.19 (A)(1)(a) (Branch Circuits) which specifies that branch circuits supplying a continuous load must have an ampacity of 125% of the continuous load. You may not be considered qualified to argue with the electrician, but the electrician must follow the code. Good luck with it.

As Neil notes, 15 hours is an average time for a 1227 in good condition. We have 2 of them dedicated to glaze firing at the community studio I manage, and the timing generally is around 13-14 hours when the elements are new. As the number of firings progresses, the times stretch out to 18-20 hours, which sometimes exceeds the time available on the dial. That is the clear indication I need to requisition funds from park HQ for new elements. So, in this test firing of your kiln, be prepared for it to take more or less time than expected based on potentially unknown condition of the elements.

Jumping back in on this latest wrinkle in the question... As dh notes above, the technically proper representation is 1.46, as the technical definition of S.G. is the ratio of the weight of the slurry to the weight of an equal volume of plain water. 100ml of water weighs 100g and (in this example) 100ml of glaze weighs 146g. So, 146÷100 = 1.46. If you are using a 100ml syringe to weigh your glaze on a digital scale, the number on the screen is the S.G. after mentally shifting the decimal 2 places to the left. I would guess that some might just say ".46" because the 1 is implicit for glaze slurries that are heavier than water, or maybe call it 146 because the location of the decimal isn't that important. 

But moving on to the 2-digit number "46", you may find yourself in deep doodoo. In the mid 1760s, a French pharmacist named Antoine Baume "invented" a hydrometer scale for measuring the density of his liquid potions. That scale was based on the density of salt water, and is generally expressed as "degrees Baume". By whatever coincidence, 45 degrees Baume is 1.45 specific gravity. However, the rate at which the Baume scale increases or decreases is different than the rate at which technically proper S.G. changes. Consequently, terra sigillata at 1.20 specific gravity is about 24 degrees Baume, and casting slip at 1.80 specific gravity is about 64 degrees Baume. If you are using a commercial hydrometer, it may or may not have both scales marked in it. I have several hydrometers that I never use (because 1. they are notoriously inaccurate for mid-fire glazes, and 2. the 100ml syringe is so much easier) that has both scales marked on the insert. But one of the large community studios that I teach at has 2 hydrometers sold by Laguna Clay that are scaled in degrees Baume only. The glaze recipe book there specifies a 2-digit number as the target "specific gravity" for each glaze. As long as nobody enlightens them about the technical truth behind that number AND they continue to use the same hydrometers to measure their glazes, they will be okay. But heaven help anybody who takes that recipe and supposed specific gravity somewhere else.

The specific gravity is a measure of the ratio (by weight) of the glaze materials to the water in the slurry. When applying glaze to bisque, the water is immediately absorbed into the porous ceramic while the solid particles of the materials are trapped on the surface because they don't fit through the pores. If there is too much water in the slurry (the specific gravity is too low), the bisque will become saturated before enough glaze materials have been deposited on the surface.  If there is not enough water in the slurry (the specific gravity is too high), the glaze materials will overload the surface of the pot before much water has been absorbed by the bisque. Both conditions will adversely affect the outcome during the firing.
Once the specific gravity has been adjusted to the proper ratio for that glaze and that particular method of application, the viscosity of the slurry can be adjusted with a flocculant or deflocculant to achieve the desired creaminess, thickness, runniness, or whatever you want to call that aspect.

Jumping back in on this latest wrinkle in the question... As dh notes above, the technically proper representation is 1.46, as the technical definition of S.G. is the ratio of the weight of the slurry to the weight of an equal volume of plain water. 100ml of water weighs 100g and (in this example) 100ml of glaze weighs 146g. So, 146÷100 = 1.46. If you are using a 100ml syringe to weigh your glaze on a digital scale, the number on the screen is the S.G. after mentally shifting the decimal 2 places to the left. I would guess that some might just say ".46" because the 1 is implicit for glaze slurries that are heavier than water, or maybe call it 146 because the location of the decimal isn't that important. 

But moving on to the 2-digit number "46", you may find yourself in deep doodoo. In the mid 1760s, a French pharmacist named Antoine Baume "invented" a hydrometer scale for measuring the density of his liquid potions. That scale was based on the density of salt water, and is generally expressed as "degrees Baume". By whatever coincidence, 45 degrees Baume is 1.45 specific gravity. However, the rate at which the Baume scale increases or decreases is different than the rate at which technically proper S.G. changes. Consequently, terra sigillata at 1.20 specific gravity is about 24 degrees Baume, and casting slip at 1.80 specific gravity is about 64 degrees Baume. If you are using a commercial hydrometer, it may or may not have both scales marked in it. I have several hydrometers that I never use (because 1. they are notoriously inaccurate for mid-fire glazes, and 2. the 100ml syringe is so much easier) that has both scales marked on the insert. But one of the large community studios that I teach at has 2 hydrometers sold by Laguna Clay that are scaled in degrees Baume only. The glaze recipe book there specifies a 2-digit number as the target "specific gravity" for each glaze. As long as nobody enlightens them about the technical truth behind that number AND they continue to use the same hydrometers to measure their glazes, they will be okay. But heaven help anybody who takes that recipe and supposed specific gravity somewhere else.

Just to add, it’s a way to achieve more repeatability / dependable applications for each particular glaze.

The specific gravity is a measure of the ratio (by weight) of the glaze materials to the water in the slurry. When applying glaze to bisque, the water is immediately absorbed into the porous ceramic while the solid particles of the materials are trapped on the surface because they don't fit through the pores. If there is too much water in the slurry (the specific gravity is too low), the bisque will become saturated before enough glaze materials have been deposited on the surface.  If there is not enough water in the slurry (the specific gravity is too high), the glaze materials will overload the surface of the pot before much water has been absorbed by the bisque. Both conditions will adversely affect the outcome during the firing.
Once the specific gravity has been adjusted to the proper ratio for that glaze and that particular method of application, the viscosity of the slurry can be adjusted with a flocculant or deflocculant to achieve the desired creaminess, thickness, runniness, or whatever you want to call that aspect.

Fine with me too. It's an interesting additional level of glaze chem. Thanks Bob for originating it.

With all due respect to Occam shaving with his razor, aren't we complicating things here? Move the picture to your desktop or wherever you keep pictures. Right click on the picture, and one of the options in the top group is "Edit with Paint 3D." Click on that and the picture will open right into Paint 3D. I'm not going to engage a debate whether the new Paint 3D is better or worse than the old Paint (or that both are abominations), but it is Win10's default built-in raster image editing  program. Once in Paint 3D, the crop tool is right there above the image. Click on the crop tool and the image will be surrounded by a white line with little white circles in the corners and midpoints. Push any of them in with the mouse to change how the white lines enclose the part of the picture you want to keep. Click Done when you like it. Then click on in the Canvas item in the tool bar across the top. This will surround the image with square white dots instead of the round ones in crop mode. With your mouse, drag any of the corner spots inward and the image will shrink. (Don't use the spots in the middle of a side - they will squish and distort the image. We just want to smallify it.) When done with this step, go to File and Save As to a new filename. This preserves the original in its full bigified glory. Find the new picture (yeah, Winblows will always put it somewhere you can't easily find it), hover your mouse over it and the preview box will show the file size. It needs to be less than 1 MB to be uploaded here. If the new picture isn't small enough yet, rinse and repeat with the canvas resize feature.