Oil-Furnace Repair and Troubleshooting – Mother Earth News


It is fairly easy to diagnose and repair home stoves, but precautions are required.

Overall, oil stoves are among the most durable household appliances. While many manufacturers claim their appliances will only last 10 years, a homeowner can often expect 15 to 20 years of service life from a properly maintained stove.

However, this doesn’t mean that an oil burner doesn’t develop a few discomforts every now and then, typically on the coldest night of winter. In some cases only minor repair or adjustment will be required, but in many cases you will need the services of a qualified heating professional to get the stove back to health. However, knowing the common problems associated with oil burners and the recommended repairs will help you better appreciate the quality of a mechanic’s work and fend off the incompetent or unscrupulous.

In the discussion below, former EcoVillage director Leroy Richter, who teaches a popular introductory oven repair course at a local technical institute, lists some common problems with oil stoves and some ways to correctly diagnose problems.

1. The oven does not start

First of all, Richter advises pressing the reset button, which starts the furnace manually. It is located either on the primary control on the chimney (on older models) or on the burner motor (on newer devices). Press the button once or twice; However, if the oven does not turn on and stay on within 60 seconds, stop pressing the button and check the fuses or circuit breaker. Stop pressing the reset button, which will only load more fuel into the combustion chamber. By the time you do and the stove finally burns, you’ll have “a hell of a lot of oil” in there, says Richter.

Sometimes the burner assembly motor burns out, says Richter. In this case the motor must be replaced. Over-oiling the sealed engine is probably the most common cause of failure. Another, albeit rare, possibility is a defective start switch on the engine, which is an inexpensive repair.

2. The burner runs but there is no fire

In this case, turn your attention to the torch nozzle first. “The opening of a nozzle is smaller than the point of a needle,” emphasizes Richter, “and even the smallest amount of water or dirt can clog it.” If it has been a while since the nozzle change, replace this inexpensive part and check whether the oven is now working properly.

To check for water, disconnect the oil supply line from the burner assembly and collect the fuel in a clean container. Hold it up to the light and look for water. A homeowner can minimize fuel pollution by following these suggestions:

  1. Turn off the oven while oil is being pumped into the tank, then leave it off for an additional hour until any debris has settled to the bottom of the tank.
  2. Have the oil supplier check for excess water in the tank with a simple test – a splash of water-sensitive paste on a long stick; If there is water, drain the tank and check for cracks.
  3. Keep the tank full of fuel, a practice that doesn’t stir up the bottom sediment as much as if you refuel infrequently.

Another possible cause is a shorted transformer. To check this, Leroy recommends disconnecting the cables to the burner motor and furnace and leaving the transformer cable in place. Take an insulated handle screwdriver (and since you are dealing with 10,000 volts, hold the insulated handle in place) and touch one of the terminals on the transformer while slowly lowering the shaft of the screwdriver into contact with the other terminal. The stream should form an arc two inches; If the arc is small, less than 3/4 inch, the transformer is weak and needs to be replaced.

Finally, dirty or cracked electrodes and shorted electrode wires can keep a furnace from burning.

Insufficient heat comes through the register

If the burner is running and the stove is on, but the heat generated is insufficient, first check the air filter; If it’s clogged, change it. Oddly enough, a new air filter becomes most efficient after it has accumulated a small layer of fluff; however, excessive build-up will impede airflow. If your oven’s air filter needs to be changed more than once or twice a year, make sure that a tumble dryer is not too close to the oven, which is causing a lot of lint.

If changing the air filter doesn’t fix the problem, then open the supply fan inspection door and see if the V-belt is broken and needs to be replaced. If the V-belt is OK, check the supply fan itself, which could be blown.

Finally, and this is also of interest to homeowners with gas stoves and heat pumps, emphasizes Richter, you should check for leaks. “I recently worked on a house that was sold twice because of excessive heating bills, and the third owner was willing to save for the same reason,” recalls Richter. “The problem was a duct that was loose and not connected. The furnace was just pumping heat into the crawl space. ”Tape and replacement of corroded parts are required to correct leaky plumbing. Even if the ducts go through an unheated basement or crawl space, Leroy recommends spending the few hundred dollars it takes to insulate the ducts of an average-sized home. “This is money well spent,” he says, “and many homeowners can do the job themselves.”

Occasionally, insufficient airflow can be traced back to an incorrectly dimensioned return air duct. A MOTHER EARTH NEWS reader wrote that he removed a sufficiently large return air grille in his house while painting and discovered that a sloppy heating engineer had cut an extremely small, too small hole behind the grille for the return air to pass through.

An indication of incorrectly dimensioned lines is a strong suction in the supply air fan room. “There should be a slight suction around the fan, but not really strong suction,” says Richter, pointing out that a heating engineer may be needed to solve complex duct problems.

Soot and smoke come through the registers

Polluted air can have a number of causes. “First open the inspection door to the combustion chamber and place the palm of your hand near the opening. If you can hold it there with no discomfort, there are probably no blockages, ”says Richter. “But if it’s too hot for you to stand and smoke comes out, there is something that will let the heat flow back out of the chamber.”

Possibilities include a clogged chimney or smoke pipe (a good point to check where the smoke pipe connects to the chimney); insufficient draft due to a smoke pipe that is too long (a rare occurrence); and a clogged or cracked heat exchanger (this is a serious suggestion that usually requires purchasing a new oven). “A cracked heat exchanger is generally the result of using the wrong nozzle size or improper setting of the burner assembly,” emphasizes Richter. “Regular furnace maintenance is important to prevent this.”

Take a look at the seals around the inspection door to the combustion chamber. Over time, Richter says, the seals would warp and tear, allowing smoke and heat to escape into the basement or crawl space. This smoke can then be sucked into the supply fan and blown into the house. Some unscrupulous stove repairers may diagnose this problem as a cracked heat exchanger and try to sell a new stove to a homeowner instead of just replacing the seals.

In addition, there are two internal seals on the heat exchanger for the inspection panels, which can warp through use and allow smoke to escape. These must be checked and replaced by a heating specialist.

Family members wake up in the morning with a sore throat and a dry nose

“An efficient stove removes almost all of the water from the air,” emphasizes Richter. “Newer ovens are equipped with humidifiers; If you have one, use it. If you have an older device, consider adding a humidifier. “

Because moist air feels warmer than dry air, a homeowner can run an oil stove equipped with a humidifier on a lower thermostat setting; thus there is a small saving in fuel consumption.

Published January 1, 1986


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