OPERATING A FRONT LOADING KILN

SITING THE KILN

Select a level, dry, well ventilated position, away from corridors and thoroughfares and with

room to allow easy loading and unloading of the kiln,. Ideally the kiln should be in its own

room. Ensure that the floor is strong enough to carry the weight of the kiln. The kiln should be not

less than 250mm from the nearest wall and be a minimum of 750mm from the ceiling. A

gap on one side sufficient to provide easy access to a wall isolator and to the rear of the kiln

for servicing is needed.Remove all flammable materials which might come into accidental contact with the kiln.

The kiln casing will get hot and so any combustible material must be kept at a safe distance.

 

Construction:

Frame

The framework is made of strong angle iron and flat section steel which is welded together.

The frame has been designed for a shelf to be positioned in the bottom section of the integral kiln stand. Very strong hinges are used for the door and the design of these permits the door to be lifted off to facilitate maintenance, repair, etc.

Brickwork

The finest available brickwork is used for the hotface. A special feature in the side walls is that the bricks are specially jointed and cemented over 2/3rds of the brick contact face in order to avoid element contact with cement to maximize element life.

Minor surface marks and fine surface cracks may be visible on some of the bricks. These

can be ignored as they are inherent from the manufacturing process of all bricks and are not detrimental to their efficiency or performance. The bricks have phenomenal performance but are easily damaged so take care not to contact with kiln shelves, props etc.

 

Please note that the kiln is subject to settlement of the bricks and it is normal for expansion cracks to occur after a few firings due to expansion and contracting due to the high range in temperature . On NO account should these cracks be filled. Back-up insulation

  Elements

These are top grade Kanthal wire, conservatively rated for long life.

  Spy & Vent holes

Spy holes are built into the kiln door and a vent port located in the roof. Additional venting, if required, is available by the design of the safety switch which permits the door to be marginally opened (`cracked’) but normally this will not be needed and is not recommended.

  Thermocouple hole

A hole is already drilled through the rear wall of the kiln and filled with ceramic fibre which can easily be removed to permit thermocouple entry.

   

ELECTRICAL CONNECTION

This should be carried out by a fully qualified electrician. A link bar is provided with the kiln and is attached to the rear electrical box lid. This should only be used if the kiln is to be single phase and MUST not be fitted to 3 phase kilns. The electrical supply MUST have a sound earth connection.

On initial firing the kiln may show a low insulation resistance reading, this is normal and will improve as the kiln dries. It is advisable for the electrician to check and retighten all electrical connections on the kiln that may have loosened in transport.

CONTROL

The controller provided with the kiln will be the controller that the kiln was test fired with at our factory and so has already done a successful firing before you receive the kiln. The controller plugs into the kiln at a socket at the rear of the kiln on the underside of the main electrics box. The plug and socket are sided and so will only fit one way. Only plug in the controller when the mains is turned off.

 

OPERATION

When the mains is turned on a contactor click will be heard. This is the safety contactor preparing the kiln for use and is normal, even if the controller is not yet set to fire. The red “mains on” light will also illuminate. If there is no display on the controller at this point check that the on-off button on the controller is in the “on” position (where fitted). Once the controller has been programmed and started a second click will be heard and, if the door is in the closed position, The kiln is fitted with a safety interlock door switch that isolates the kiln elements when the door is opened. The safety interlock switch is located under the kiln door to close the door push the door gently shut , fasten the two door catches and push the interlock handle through the rectangular hole and turn the handle clockwise.

 

HEAT FUSE

The kiln is fitted with a heat fuse that is pre set to 1280 degrees centigrade. If the kiln reaches this temperature, the kiln will be shut down by the heat fuse. Your kiln will be saved but your pottery will not. The blow temperature of the heat fuse is  adjustable and once blown can be reset by Alisdair Kettles Pottery Supplies so we can ensure that the cause of the blown heat fuse is  investigated and it does not reoccur.

MAINTENANCE

A well-built kiln requires very little maintenance. Certain common sense tasks will certainly help its life such as cleanliness and careful use. Keep the area of the door seal clear of any separating material or any other objects as once damaged the seal will need to be repaired or replaced. Keep the kiln dry and away from sources of water. REMEMBER, the kiln is for pottery and drying pottery in or around the kiln could result in premature deterioration of the kiln structure.

Care must be taken not to load the kiln so that the pottery is touching the elements. This invariably results in broken elements. The same applies to the thermocouple and heat fuse that stick through the back wall into the chamber.

When shutting the kiln door, gentle operation will also prevent accidents.

  Depending on use it advisable to check all electrical connections are tight every 6 months or so and that no cables are discolouring due to heat.

 

SAFETY CONTACTOR CIRCUIT

  This kiln is  fitted with a safety contactor and heat fuse as secondary back up against any failure or incorrect setting of the controller.

  On switching on the kiln interlock a small thud will be heard at the rear of the kiln. This is the safety contactor being energised. This also feeds the programmer on pottery kilns, shutting down the display.The second contactor (heat) does not come in until the programmer switches the kiln on.

  The heat fuse rating on pottery kilns is 1280c. Though the heat fuse will protect the kiln, it will not protect the medium being fired from the effects of reaching the heat fuse temperature.

If your kiln is fitted with electronic heat fuse this is automatic and if it requires reset please contact ourselves , failure to do so could damage the kiln , we need to check the reason for failure .

KILNS AND R.C.D. “TRIPS”

Due to the structure of kilns a certain amount of leakage to earth will probably be evident, therefore the fitting of a 30ma R.C.D. in the circuit can create a fault condition at higher temperatures, when first fired or used after a long period of inactivity. This problem is relatively rare but can be solved by the fitting of a 100ma R.C.D. consult us or a fully qualified electrician for advise.

  INITIAL FIRING

Before using the kiln it is advisable to fire the kiln empty to a temperature of 700 degrees centigrade at a rate of around 200 degrees per hour. This will dry and “settle” the kiln. The kiln is pre-fired to 750 degrees centigrade at our factory shortly before despatch and so, depending on the time delay between delivery and installation, the amount of moisture drawn from the atmosphere by the kiln may well be minimal. On the initial firing, a slight odour may be emitted, this is the remnants of binding resins in the boards and should stop after one or two firings. One reason that we pre fire the kiln is to minimise the amount of resin odour left in the kiln before the customer receives the kiln.

We suggest that the kiln controller is set to fire the kiln to a low temperature and end, say 150 degrees, whilst being monitored to ensure that it is switching off the kiln and that no problems have occurred during transport.

 

Kiln Furniture

 Kiln batts sufficient to cover the base elements and provide a loading platform were included with your kiln. Position these so that there is even space all round with a gap in the middle (if two or more batts).

Additional shelves are created by using three or four prop columns spaced equidistantly to

evenly support single shelves and four or five prop columns to support shelves consisting of

two batts. All prop columns should be placed so that their weight acts down over prop columns below. It is best to use base supports and collars to spread the load where shelves have two or more batts

Before batts are used they should be thoroughly dried and sounded. A dry batt can be supported by hand at its centre or suspended between thumb and finger and tapped with a metal object. If it does not ring a crack may be suspected. A dull sound suggests the batt is not dry. Store batts on edge in a dry place.

  Use of batt wash

If satisfactory the upper surface of each batt should be painted with batt wash mixed with water to a thin, creamy brushing consistency. Sufficient should be painted on to cover the batt without show-through. Periodic replacement of this coat will be necessary. Do not paint props or any kiln brickwork with batt wash. Allow batt wash to dry before loading ware and be careful to avoid transferring traces of batt wash on fingers etc. to the ware.

  FIRING

There is a bung located on the kiln roof this should be used to allow moisture to be released from the interior during the earl firing process and should be replaced after the kiln has reached 600 degrees centigrade. This bung can be removed to speed up the process of cooling .

There is a spy hole bung located on the door , this is to allow inspection of the chamber during the firing the operator must TAKE CARE when using this as this will allow heat to escape and safety equipment such as darkened lenses should be used.This bung should NOT be used to cool the kiln .

When cooling the kiln the door should NOT be opened above 80 degrees centigrade , above this temperature you could damege the kiln and pottery pieces would crack.

  Only qualified personnel should operate this equipment.

WE ARE PLEASED TO INSTRUCT ANYONE BUYING A KILN FROM US , ON HOW TO USE IT.

 

SERVICING THE KILN.

The kiln should be inspected annually by ourselves. Any work should be carried out by us as this is a specialist piece of equipment , and we have the specialist knowledge and equipment to maintain kilns .

 

SPARE PARTS-BACK/UP

  We have in stock ALL the spare parts for the kiln, We pride ourselves on our back up and after sales service and so in the unlikely event of any problems please do not hesitate to call our staff for friendly help and advise.

  CONNECTION

Your kiln is supplied ready for connection to a 3-phase supply.As always we recommend that the connections are done by a qualified electrician.

  REMEMBER the kiln bricks are of ceramic composition and as such severe shocks to the chamber must be avoided.

It is important that the earth bonding wires are re-fitted correctly and soundly.

Before final connecting it is advised that all electrical connections are checked and re-tightened by a competent person.