Boiler and Furnace Conversions – OIL TANKS AND OIL PIPING

OIL TANKS AND OIL PIPING

Local codes and the National Board of Fire Underwriters will provide information for the installation of oil tanks and piping.

In oil piping, copper tubing is commonly used for suction and return lines. A % inch OD minimum is recommended for lines under 30 feet in length. If the suction and return lines exceed 30 feet, then Y2 OD copper tubing is recommended.

Other suggestions for the installation of the oil storage tank and piping include:

1. Use a good quality pipe joint compound and make your pipe thread connections as tight as possible.

Keep the lines between the oil tank and burner as straight as possible (avoid kinks and traps).

1. Keep the connections in the return line to a minimum.

2. Check tubing flares and connections for air leaks (an indi­ cation there is a poor seal resulting from improper meeting).

The two basic types of piping arrangements are: (1) the single line system and (2) the two-line system. These two piping arrange­ ments are primarily distinguished from one another by the location of the oil storage tank with respect to the oil-fired conversion burner.

A single line piping arrangement is used only where the oil storage tank is located above the level of the oil burner. No return line is necessary. The oil is taken from an outlet in the bottom of the storage tank and fed by gravity to the burner. The slope of the pipe should be gradually downward (approximately V2 inch per foot) to a point directly below the burner connection. This downward slope in the line is designed to prevent the formation of air pockets and bubbles. The installation of a shut-off valve in the line is recommended.

A two-line piping arrangement is required where the oil storage tank is buried at a level below that of the burner.

INSTALLING A CONVERSION OIL BURNER

Conversion oil burners should be installed in accordance with the regulations of the National Fire Protection Association (NFPA Bulletin No. 31) and local codes and regulations. Read these reg­ ulations and the manufacturer’s installation instructions before making any attempt to install the burner.

If the furnace or boiler was originally designed to burn solid fuel and the ash pit is not used as a part of the combustion cham­ ber, the ash door should be removed to prevent the accumulation of vapors in the ash pit. If removal of the ash door is not feasible, then some other means of bottom ventilation must be provided.

Before installing the burner, check the condition of the boiler or furnace. It must be in good condition or repair. The flue gas passages and combustion chamber must be tight against leaks. Reseal or reset the sections of a cast-iron boiler or furnace. Re­ place any damaged parts. The boiler or furnace should also be as clean as possible before installing the burner.

A combustion chamber must be provided that is in accordance with the specifications of the burner manufacturer. Read the ap­ propriate ections in this chapter (e.g. COMBUSTION CHAM­ BER REQUIREMENTS, etc.) for more information.

If you are satisfied that the boiler or furnace with which you are working satisfactorily meets the conditions mentioned in the previous paragraphs, then you are ready to install the conversion oil burner. The basic steps recommended for installation are as follows:

1. Position the burner on its mounting flange or pedestal so that the burner air tube is flush with the inside surface of the combustion chamber front wall. Do not allow the burner air tube to extend into the combustion chamber.

2. Adjust the burner tube on pedestal mounted burners so that it pitches downward about llh inches. Any fuel in the burner tube will then drain into the combustion chamber.

3. On flange mounted burners, the distance from the flange  to the end of the air cone will depend upon the require ments of each installation. Remove the air cone before installing the flange.

4. The distance between the center of the nozzle and the floor of the combustion chamber must be correct. If it is too close, it will result in flame impingement and carbon­ ization. On the other hand, a nozzle placed too high will result in excessive flame noise and poor combustion.

5. The fuel pump should be adjusted for the oil pressure recommended by the manufacturer.

6. Adjust the air supply to the burner with the air inlet band.

Rotate the air inlet band to the required position (the one which will deliver the smallest amount of air and still maintain clean combustion) and secure it in position.

7. Make certain the size and spray angle of the nozzle is correct for the installation (check the U.L. rating plate).

8. Install the nozzle and check the electrode tip position in accordance with the manufacturer’s instructions.

9. Prime the fuel pump (see the manufacturer’s instructions).

STARTING A CONVERSION OIL BURNER

Before attempting to start the oil burner, you should first carefully read the manufacturer’s instructions. Unfortunately, these are not always available on older heating installations. If this is the case and you do not possess the necessary expertise to operate the burner without an instruction manual, I would strongly recom­ mend calling a professional for a service call.

Always test the oil lines for possible leaks and make the necessary repairs before starting the oil burner. Consult the manu­ facturer’s instructions for bleeding the fuel pump. The bleed valve on the fuel pump is designed to facilitate air purging, cleaning, and priming. See Chapter 1, Volume 2 (OIL BURNERS) for additional information about fuel pumps.

Check the electrical wiring diagram (if one exists) to make certain that the burner is correctly wired. Problems with an oil burner can often be traced to incorrect wiring. All wiring must be in accordance with the National Electrical Code as well as local codes, standards, and regulations.

It is important to make certain that the primary and limit controls are operating properly. Test the primary control by first removing the motor lead from the burner and then energizing the ignition circuit by throwing the switch. If the primary control is operating properly, the ignition will shut off within two minutes after the switch is thrown. On the other hand, if the ignition fails to shut off after two minutes, the primary control should be replaced.

Check the fuel level in the oil storage tank. There must be enough oil to operate the burner. Open both oil valves (at the oil storage tank and at the boiler or furnace).

You must have an adequate air supply for efficient combustion. The basic ventilation requirements (see VENTILATION RE­ QUIREMENTS in this chapter) must be provided for when in­ stalling the oil burner. It is also important to determine if the secondary air setting is correct. If there is smoke or soot present when the oil burner is operating, the air setting must be corrected.

If all the suggestions in the previous paragraphs have been followed and the necessary adjustments or repairs made, the oil burner can now be started. The procedure for doing this is basic­ ally as follows:

1. Mak_e certain that all controls have been set in normal starting position.

2. Make certain that the oil valve in the oil supply line is open.

3. Set the room thermostat 10° above the room temperature.

4. Check the reset button on the primary control to make cer­ tain it has been reset.

5. Open the air control band on the burner to about half open.

6. Throw the main electrical switch to ON. The burner should now start, ignite and burn. If it does not, recheck Steps 1 through 5. If you still experience difficulty in starting the burner, consult TROUBLESHOOTING OIL BURNERS in Chapter 1, Volume 2 (OIL BURNERS).

7. Allow the oil burner to operate for about fifteen minutes, and then shut it down and give it time to cool off. After it has cooled off, restart it to be sure it operates properly on a cool start.

While the oil burner is operating (Step 7), you should take the opportunity to make a number of tests. Check the fuel pump pres­ sure with an oil pressure gauge. These should be factory set.

Adjust the air control band on the burner until 0 + smoke is obtained with a smoke tester. Adjust the draft control (if neces­ sary) to obtain at least .02″ w.c. of draft over the fire.

SERVICING A CONVERSION OIL BURNER

Protecting the oil burner motor from unnecessary wear is extremely important. At least once a year (but not more than three times a year), preferably at the beginning of each heating season, place about ten drops of #20 SAE oil in each oil port of the burner motor. After you have oiled the burner motor, clean the fuel strainer and change the oil filter cartridge. Clogged fuel strainers are a common source of trouble. In rotary- and gun-type oil burners, these components are usually located either at the point at which the oil line connects to the tank or at the oil line connection to the burner. Follow the manufacturer’s instructions for removing the fuel strainer, and clean it with a stiff wire brush or a blast of compressed air.

Be sure that you are using the correct weight of oil. If the oil is too heavy, the burner motor will start but it may fail to estab­ lish a flame. Continued use of the wrong oil may cause damage to burner components. ·

Soot should be periodically removed from the burner and com­ bustion chamber. Commercial soot removers are available for this purpose. When burning out a layer of soot, take care not to ignite a soot fire in the chimney. This could be very dangerous because it may lead to the igniting of combustionable materials near the chimney. The hard layer of carbon that frequently forms on the bottom of the fire pot in burners should also be removed.

Other servicing recommendations for conversion oil burners are as follows:

Check the furnace or boiler for possible air leaks. Any that are found should be sealed (an asbestos cement is recom­ mended) because they interfere with combustion efficiency.

1. Check the burner nozzle in gun-type burners. If it is dirty, remove and clean it according to the manufacturer ‘s instructions.

2. Check the position of the electrodes in rotary- and gun-type oil burners. They should be positioned near but out of the direct spray of the oil.