this thread is a couple weeks old although been away. You should have your furnace serviced if you are not sure when it was serviced last. Then you have a "starting point" for future reference in keeping your tune up current. As others said you should have it tuned once a year. If you decide not to have it tuned on regular yearly basis, at least replace your air filter monthly (should be doing this regardless) for standard filters. You need proper airflow across your heat exchanger to transfer heat into your home. Several things occur when the tune up is out dated. The oil filter and nozzle begin to load with debris and will drop your oil pump pressure a little which in turn causes your air/fuel ratio to change. Pump pressure is critical for proper oil drop atomization with the combustion air. The oil nozzle has a very small screen or stone filter which will begin to clog once the main oil filter begins to fully load with crud. If you have to much combustion air, your heat is going out of the flue. Most standard oil burners will produce a flue/chimney temperature around 350-575 degrees F net. When you add more combustion air, it will push that hot flue exhaust out of your furnace faster than your heat exchanger can absorb the heat of combustion and in turn dropping your supply duct/register temperatures. There is a critical ratio of fuel/air during combustion that must be maintained to get the most heat out of every gallon of fuel oil. A simple way to understand what I am talking about is this. One Gallon of fuel oil when burned properly will produce right around 144,000 BTUs (British thermal units). If you are using a .50 GPH (Gallons per hour) oil nozzle, you are introducing 72,000 BTUs to your combustion chamber in theory. A .75GPH oil nozzle will produce 108,000 BTUs in theory (with perfect combustion). If your furnace was serviced in the past by non-qualified persons and they just thrown in whatever nozzle was available, your furnace would be operating outside of what it was designed throwing your money out the window. Most residential standard air to air oil furnace would use a nozzle around the .75GPH range (3/4 gallons per hour or 108,000 BTUs introduced to your heat exchanger to be absorbed. Some larger homes would run larger nozzles although the point I am making is you must operate within the design of the manufacturer of both the oil burner and the furnace together. Outside of that design and your wasting money. Another point to make for our geographic area is that oil burner homes that utilize an above ground oil tank (275 Gallon usually) will have their oil burner oil pump pressure change to lower pressures on extremely cold days due to the oil itself inside the oil tank getting thicker and harder to move through the lines and therefore change the air/fuel ration. It is a good idea to add some kerosine
(never add gasoline) to your oil tank on very cold months or ask your oil burner tech to sell you an additive that the trade uses for this purpose. As others mentioned, A programable thermostat with adaptive recovery is a must for your house as explained by your schedule and lifestyle. Let that temperature drop back to 50 0r 60 degrees while everyone is gone. It sounds like because your house takes a long time to heat back up after thermostat setback with oil heat, you either have a burner/furnace not set up properly or the furnace itself is not sized for home properly. When you make a choice on a company, make sure it is a "oil Burner Technician" and that individual is qualified for that type of system. Ask them questions while they work. You can get alot of tips from your tech while they work. Most don't mind talking while they work. A quick way to get a very rough idea about your furnace operation is get a simple accurate thermometer and place down inside your register and allow furnace to operate around 15 minutes. You should be seeing 135-155 degrees depending on ductwork/furnace design. A boiler is completely different. If it is air to air type of furnace, the above temps should give you a very rough idea. If you are only seeing around 100-120 degrees you are operating outside the specs. If you are seeing above 160 degrees, you are going to ruin your furnace heat exchanger in time (alot of gross oversized oil nozzles cause this overheat). The most important tip is to make sure you have minimum of one carbon monoxide alarm that is within 5 years old (check the date on the back of the alarm for an expiration). Carbon Monoxide will kill you and your family in silence. I think it is best to have at least two in the home for insurance. You will be paying $100-150 for a tune up although if completed by a qualified oil burner tech, you will get that paid back to you through efficient operation this same year.
