Elite Furnace Manual
Sears International Online Shopping If you are planning to visit the United States, or have friends and family here, shop at Sears to get everything you want—including gifts for yourself or others. Shopping online in the U.S. At Sears could not be easier. You can pay for your order in a store or even use an international credit card. Once you place an order, you (or someone you know) can pick it up at a Sears store, have it shipped to over 100 countries—whatever is most convenient for you. If you are looking to do some international online shopping, be sure to visit.
If the furnace starts intermittently, though it runs fine when it does start, the problem is likely the furnace control relay running from the thermostat to the furnace. Unfortunately the Lennox Elite Series furnace is known for this problem. It's a simple relay box attached to the side of the furnace with two wires running to the thermostat. There should be a few lights on the box as well.
If the lights do not come on, then the furnace relay circuit board is broken. If they flash on and off, then there's a loose connection in the wiring, either running to the thermostat, or passing into the furnace itself. First check the access panel of the furnace. If it's loose, it can rattle and create a rumbling noise throughout the entire house.
Next check the fan belt inside the access panel. Some lubricant spray might be in order, though if the fan belt is frayed it should be replaced. Next check the blower motor; it may be in need of oil, which should be fed through the induction ports on the base of the furnace unit.
Finally the noise could be caused by dirty burners. If you're using old oil, this can cause the burners to become dirty faster, though they should usually be cleaned by a technician once every five years. If the blower motor won't stop running regardless of the actual temperature of the home, there are two possible causes. The blower control could be incorrectly set, or the limit switch on the Lennox Elite Series furnace unit itself isn't set. Go to the thermostat and switch it to the AUTO setting, then go to the furnace unit itself and reset the limit switch.
Lennox Elite Furnace Installation Manual
You may need to indicate the time and temperature threshold which you will allow the blower to run before it automatically shuts itself off. If you've reset the limit switch, but the blower still won't stop, then the limit switch is broken and needs to be repaired.