For starters, the concept of forced-air heat is essentially the same regardless of the heat source Ė oil, gas, or heat pump. Basically, air is heated in an exchange plenum, then distributed throughout the home via ducting. Oil and gas units achieve this by heating with a flame. Unlike gas, which is supplied under pressure and operates similarly to a gas stove, oil systems operate more like an automobile. The oil is stored in a fuel tank, located in the basement, side of the house, or even buried in the yard. There is also a fuel filter, and a pump that draws the fuel from the tank to the heater unit. It is then squirted into the firebox though an injector, similar to fuel injection in a car. Also, like a car, you pay for the fuel before you use it, not as you use it.
It is important to know how old your heater is. I think itís safe to say itís not original. The age of the home predates the common use of forced-air systems, and I would be surprised, depending on the region the home is located, if it was not originally heated with coal. Still, the unit could be 40+ years old. The big thing with forced-air units which employ some sort of combustion t generate heat, is the exchange plenum. This part of the heater is essentially 2 chambers separated from each other. One chamber is used for the air being heated for the home; the other is for the combustion. The idea here is to keep the two sealed apart, but when they get old, the plenum can crack, allowing deadly gasses to pass into the heated air, and on throughout the home. The most dangerous of these gases is Carbon Monoxide. Iím sure you have heard of that.
Even if it is only a couple of years old, a thorough inspection by a qualified person is always the rule. Other problems, such as oil leaks and pump failures, can also cause grief. Most qualified home inspectors will be able to look for the telltale signs, like soot around the vents in the room or water in the bottom of the oil tank. Then, if warranted, they will usually recommend an additional inspection from a heating specialist. You can spend from $1500 - $4000 for a heater replacement.
Oil tanks can be another potential issue. They can last from 30-40 years. When they fail, the oil leak can become an environmental issue. The EPA and your local municipality closely monitor oil tank replacement, especially if it is underground. You can, however, obtain insurance. A new tank can run $1000, installed. If you were to decide to convert to another type of heat source, such as gas, you would still be required by law in most places to remove the old oil tank. And oil heaters cannot be converted to gas.
If it sounds like Iím against oil, Iím really not. Itís just different from what I was used to. After only knowing gas and heat pumps, I now have it in my current home. It took me awhile to figure things out. For one, you will need to find a supplier to buy oil from. Mine has me on a budget for the heating season. My payment includes a maintenance contract, tank insurance, and oil. In this way, they guarantee I will never run out of oil. You can, of course, save some money by shopping around for each tank full, but then you will need to check your fuel level yourself, and run the risk of running out, 2Am January 22nd.
My oil tank is 45 years old, and buried in the front yard. It shows no signs of leaking. I now live in an older home than my last one, much bigger, and with less insulation, and still my bills are about $25/month lower, and my home is warm. Of course, my last home used a heat pump.