TECHNICAL SUPPORT HOT LINE HOURS: 7:30-3:30

Transcription

1 TECHNICAL SUPPORT HOT LINE HOURS: 7:30-3:30 TO: Service Providers BULLETIN No: FROM: SUBJECT: BOB VAN WYCK Technical Support Manager Burner Pilot Tube Replacement DATE: Feb 1, 2001 Products Affected: Rack Ovens Number of attachments: 7 pages MESSAGE: The purpose of this bulletin is to inform our service providers of a Burner Pilot Tube Replacement Kit which is available to be used on all ovens, manufactured after 1997, that are experiencing failure due to carbon fouling of the ignitor. See the attached information for diagnoses procedure and conversion instructions. LUCKS FOOD EQUIPMENT COMPANY nd Ave. So. Kent, Washington 98032

2 Burner Pilot Tube Replacement The Reliant R15/R20/R30 rack oven model line uses an Eclipse burner with an ignition transformer to ignite the burner utilizing an ignitor device similar to an automotive spark plug. A small number of these ovens are experiencing a problem with carbon fouling of this ignitor (spark plug). Included with this bulletin is a field procedure to replace the burner pilot tube with a smaller diameter tube. This change will lower the BTU of the pilot flame. In lowering the pilot flame BTU the possibility of carbon fouling of the ignitor is greatly reduced. Any Lucks Rack oven that has an Eclipse Thermjet burner and is experiencing flame failure should be diagnosed as follows, 1) Is the flame failure due to a failure to ignite the pilot gas? 2) Does the ignitor (Spark Plug) have carbon on it when inspected? 3) Is the pilot tube currently a 3/8 inch aluminum tube? If all of the above can be answered YES, after an on-site investigation, then the technician should order the retro kit (Kit Number ) from the Lucks Parts Department and schedule the field change with the customer. As a short term fix the ignitor may be cleaned of the carbon with a cloth and re-installed, allowing the oven to work again. Additionally, if the oven is out of warranty you may purchase these common parts locally and follow the instructions included with this bulletin.

3 Burner Pilot Tube Field Retro Kit Document Number Page 1 of 6 Burner Pilot Tube Field Retrofit (Kit Number ) Parts Supplied In Kit: Description Quantity Lucks Part Number - Instructions (this document) 1 Ea Fitting, Elbow, 3/8 NPT x ¼ comp 2 Ea Burner pilot tube ¼ x 8 length 1 Ea Special Tools Required: None

4 Burner Pilot Tube Field Retro Kit Document Number Page 2 of 6 Overview: The Reliant R15/R20/R30 rack oven model line uses an Eclipse burner with an ignition transformer to ignite the burner utilizing an ignitor device similar to an automotive spark plug. A small number of these ovens are experiencing a problem with carbon fouling of this ignitor (spark plug). It has been determined that the pilot flame can be too large, resulting in the ignitor being immersed in the pilot flame, quenching the flame at the ignitor, causing carbon to form on the ignitor. This field retrofit is to identify and replace the burner pilot tube to reduce the pilot flame BTU s. It is important to note that carbon fouling can also be caused by air/fuel ratio issues and that verification of factory specified air/fuel settings are required. Identification: This retrofit applies to all Lucks Reliant R15/R20/R30 ovens manufactured since 1999 that have an Eclipse TJ50 or TJ100 burner. See picture number 1 to the right for a typical burner configuration. Picture 1 Field Modifications Required: The burner pilot tube and the compression fittings will be replaced. The following steps will guide you through the process. A) Shut off the gas and disconnect the power to the oven 1) Flip all the oven s circuit breaks to the off position. 2) Rotate the manual gas valve to the off position.

5 Burner Pilot Tube Field Retro Kit Document Number Page 3 of 6 Detail 3 Detail 2 B) Identify and remove the existing burner pilot tube and fittings. 1) Review the detailed picture below. Remove the items identified by the arrows. Remove 2 each 3/8 NPT x 3/8 Comp fittings Remove 3/8 Alum Tube Detail 2 Detail 2

6 Burner Pilot Tube Field Retro Kit Document Number Page 4 of 6 C) Install the new brass fittings 1) Apply gas service rated thread tape to the 3/8 NPT fittings. 2) Thread these fittings into the black iron pipe tee and into the pilot gas valve. Be sure these fittings are tight, and aligned so that the compression fittings are facing up (just like the fittings you removed). D) Verify length and shape of the new ¼ alum. pilot tube The new pilot tube is 8 inches long, and should be shaped as shown in detail 3 below. If not you may use the detail below as a template to shape the tube. Be sure not to kink or crimp the tube while shaping. Detail 3 E) Installing the new ¼ alum. pilot tube 1) Install the nut and ferules onto the tubing. 2) Fit the tubing into the fittings. Be sure that the tube ends fit fully into the fittings. 3) Slide the ferules and nuts down the tubing to the fitting, tighten the nuts until fully tight. F) Functional Testing 1) Remove and clean all the carbon from the ignitor, reinstall the ignitor. 2) Flip on the breakers, be sure the gas supply is still off.

7 Burner Pilot Tube Field Retro Kit Document Number Page 5 of 6 3) Follow these steps to insure safe operation. Turn on the oven, call for heat. Verify that these things happen in order. A) The Honeywell flame controller located in the left mullion has a flashing green light. B) The combustion blower starts. C) After about 10 seconds the pilot gas valve and transformer are powered. D) 10 seconds later the pilot gas valve and transformer loose power and the Honeywell s flame failure buzzer sounds. 4) If all went well with steps A-D above then turn on the manual gas valve, press the reset button on the Honeywell, and fire the burner. 5) The burner should perform in all ways the same as before. No operational differences should show up while testing. Careful examination of the pilot flame through the sight glass will show a flame with the center area dark. 6) Once the burner is firing correctly a verification of the burn performance is required. Verify the following air/fuel mixture to the procedure on the next page.

8 Burner Pilot Tube Field Retro Kit Document Number Page 6 of 6 Adjusting the Thermjet TJ50/100 Burner R(M)15/20/30 Rack Ovens To adjust the burner on a Lucks Rack Oven you need two special tools. - Water Column gauge with a range of 0-10 inches W.C. - Exhaust analyzer, Carbon Monoxide and Oxygen sensors WARNING: Injury or death may result if the burner is allowed to operate with exhaust levels of Carbon Monoxide greater than 50 PPM. ADJUST GAS PRESSURE Install a barbed fitting into the port on the manual gas valve just after the regulator. A tube must connect from the fitting to the HIGH side of your gauge. With the oven NOT running you should see a pressure of at least 6 inches W.C. Start the oven and verify that the pilot and main burners fire on the TJ100 burner. While running, the gas pressure should be 4.5 inches W.C. The regulator will have a lead seal you must cut to remove the cap and gain access to the adjusting screw. If adjustments are required, adjust the regulator by turning the screw to get 4.5" W.C. while running. Turning the screw counter-clockwise decreases the gas pressure. Note: You may only cut this seal on initial installation without prior approval from the Lucks Company, and you must notify Lucks technical support within 72 hours that you have done so. At all other times prior approval must be obtained from the Lucks Company to cut security seals, or the equipment warranty may be voided. AIR ADJUSTMENT The air shutter is located inline with the flex tubing coming from the combustion fan. It has a bolt to lock it in place, raise it to increase air, lower it to decrease air. The air shutter should not be raised any more than 3/8" above its lowest point. Look into the sight glass on the burner, you are looking for a blue flame with a large quantity of yellow. NOTE: Very small adjustments make a large change at this point. Using the exhaust analyzer place it into the exhaust BELOW the draft hood. It should be in the middle of the tube, at the hottest spot. Note that you may have to drill a 3/8 hole into the exhaust ventilation. The settings you must get are... Carbon Monoxide (Co) = less than 50 PPM ( 0 is expected ) Oxygen (O2) = 6.5 to 7.5 percent O2 With the oven running adjust the air shutter to achieve the desired performance and exhaust results. Adjust the shutter DOWN to decrease the air, which will INCREASE the flames heat. Watch the oxygen and Carbon Monoxide results carefully, decrease the air until the Carbon Monoxide level begins to increase, then increase the air slightly and stop. If you have any questions, please call the Lucks Technical Support Hot Line at