Can You Use Diesel Fuel in a Fuel Oil Furnace Without Damaging It?

I heat my house with fuel oil. A year ago, the oil company I used was sold. During the buying/selling process, the day-to-day operations suffered. As a result, all the supplier's customers on my road, including myself, didn't have our fuel oil tanks refilled on the first of the month as scheduled. My tank ran out of fuel soon after, in the middle of a frigid January night. It was too cold go to without heat. Since it was an emergency, I bought a five-gallon can of diesel fuel from a neighboring farmer. When my furnace quit working a day or so later- after the tank had been filled with fuel oil- I wondered if I had made the right decision. Read on to find out the answer to, "Can You Use Diesel Fuel in a Fuel Oil Furnace Without Damaging It?"

According to the Furnace Repairman and Exxon
I explained what had happened to the repairman, "John." He said, you can safely use diesel fuel in a pinch. Diesel fuel is known as a "middle distillate" because it's heavier than gasoline, but thinner than oil that's used for lubrication purposes. It's used in engines where "compressed, high-temperature air in the combustion chamber ignites it spontaneously, according to exxon.com. Diesel fuel is in the same "middle distillate" class as fuel oil. Fuel oil and diesel fuel are pretty similar. However, while the diesel seemed to burn okay in my furnace, it did produce an odor. I can't smell fuel oil at all unless the furnace is malfunctioning and it's not being burned properly.

Fuel oil is more refined than diesel fuel. That's why diesel produces a smell. And because there are more contaminants in the latter, they can clog up your heating system, especially the fuel tank filter. That is why my furnace quit running. Not because of using diesel fuel, John said. When the tank ran dry, it sucked some sludge present in the bottom into the filter.

Exxon.com says, "Our heating oil promises to meet your energy needs as well as meet or exceed ASTM D 396 standards (in the US) for fuel quality, combustion quality and corrosion resistance. And our heating oil is backed by our quality assurance program - to help minimize or eliminate contaminants and help keep heating oil equipment running trouble-free."

Besides containing more contaminants that can clog your heating system, you wouldn't want to use diesel fuel in your fuel oil furnace full-time because it costs more per gallon; it's taxed more.

So, long-term damage may not occur to your fuel system heating system by using diesel, according to John. It can, however, cause it to clog up repeatedly and malfunction.

Resources
http://www.exxon.com/USA-English/GFM/Products_Services/Fuels/Diesel_Fuels_FAQ.asp