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Why Is My Oil Furnace Not Heating the Water and the Heat Isn't Turning On?
The Flame Rod
Inside the burner, a component called a flame rod produces a spark that, in turn, ignites the fuel that brings the water in the boiler up to a predetermined temperature. If the flame rod's connectors are dirty, the sparking mechanism will be inadequate or absent altogether. The answer may lie in removing the rod and cleaning its tips with a light sanding of steel wool. A severely clogged or corroded flame rod may need to be replaced.
An aquastat controls the temperature of the hot water in the boiler. The water must achieve a preset temperature before the circulating pump is activated and the heated water moves through the pipes to heat your home. In colder weather, the aquastat should be set to maintain the water at 180 degrees Fahrenheit. If the weather is milder, your heating needs are reduced. Resetting the aquastat to around 120 degrees may be all that is needed to fire the burner and get your system running again.
A burner requires an adequate amount of oxygen to support combustion. If you have recently replaced windows in your home, the energy-efficient, airtight environment you have created may have a detrimental effect on the burner's ability to fire and maintain a flame. The answer may lie in installing a more efficient air intake system or simply opening the furnace room window a few hours each day to replace the oxygen used by the burner.
Replacing the Burner
If the burner on your oil furnace is over 10 years old, it may be over-sized. Many older homes that have undergone renovations to improve energy efficiency may need a smaller system than the original that could have two to four times the necessary capacity. Many major heating equipment manufacturers and contractors will provide a heating and cooling load assessment at little or no cost to you if you buy a new, correctly-sized burner. The Air Conditioning Contractors of America (ACCA) publishes Manual J, "Residential Load Calculation," which is the recommended standard for assessing residential heating and cooling needs.