Can you use diesel for heating oil?
In the event that you come to an end of fuel, your burner will shut down, as there is a safety system that disables it if there is no flame if the burner is running. It's likely you'll clog up your filter, so anticipate replacing it if you do run-out (it could be good to proactively change it in the event that you operate really low, even if you do not run totally out). After replacing the filter, you will need to press the reset switch, and there could be a process to bleed atmosphere from the range (i have heard of solution technology repeat this on ours after the system shut down considering extreme cool blocking the filter with gelled gas).
This basically means, you need a site call when you run out, unless you're comfortable preserving your system your self.
My understanding is that diesel fuel has ingredients which are not necessary for an oil burner, but will do no problems for the device. You will be having to pay road fees that'll raise the price, however in an emergency, that is most likely not a concern (we keep two six gallon synthetic Jerry cans exactly with this contingency because we have a driveway that's occasionally perhaps not passable with an oil vehicle in the cold temperatures).
Edit: an internet search on "difference between fuel oil and diesel" generally seems to declare that they're mainly interchangeable, with minor exceptions - a cetane additive may (or may well not) be put into roadway diesel in some circumstances, but should not influence your oil burner negatively. Kerosene could be put into fuel oil (uncertain why), but often is not, so diesel would once again be an OK substitute.