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Killing The Fuel Oil Furnace:

By , Editor.

In the fall of 2002, about one month into the heating season, our old oil furnace began acting up. I knew it needed to have the burner adjusted and the combustion chamber cleaned, at the very least. I called our usual oil furnace service company, and I was surprised to discover that the annual service fee had gone from $70 to $115. I called some other places and found similar rates. I also found that some heating companies had discontinued servicing oil furnaces because their liability insurance rates had increased dramatically, and the number of oil furnaces was declining.

I could read the writing on the wall: The dinosaurs were going extinct. Living out in the country, natural gas is not available. I've noticed over the years that new houses in these rural areas always have propane tanks. I made some more calls and was pleasantly surprised at how competitive the propane supply industry was. All of the suppliers had special low rates to entice new customers to sign up. They install the tank and supply line for practically nothing, and then often give big discounts on your first fill up.

I began to understand why oil furnaces were losing popularity. Many years ago, oil was the fuel of choice for people who didn't have natural gas service. But oil is a dirty fuel. I would call it a filthy fuel. When I removed the back access panel on the oil furnace I couldn't believe the amount of soot in the heat exchanger. The bottom one-third of the passageways were blocked. I literally dug out what looked like yellow bricks but were actually blocks of sulfur.

Fuel oil (and diesel fuel, which is virtually identical) has a very high sulfur content. I read somewhere that the sulfur content is around 3,000 parts per million, which would be 0.3%. For an impurity, that is a very high concentration. Why should the homeowner deal with sulfur removal (with an annual furnace cleaning) when the petroleum refinery can remove it?

With an oil furnace an annual cleaning and service call is truly necessary, because the soot needs to be removed from the heat exchanger. Also, the oil spray nozzle should to be replaced and the air-fuel ratio adjusted to minimize soot buildup. As soon as the soot builds up, it begins to restrict the flow of combustion gases. If this gets bad enough, it can cause the furnace to stop functioning, or worse, can send combustion gases into the house.

What a headache! Gas and propane furnaces do not have the same maintenance needs as oil furnaces. Sure, the air filter needs to be replaced monthly, and it's a good idea to vacuum the dust off the blower every year (I just use a shop vac and a clean, dry paint brush), but most of these furnaces do not need annual cleaning of the burner or combustion chamber. True, gas and propane burners can get a small amount of soot buildup, but I've seen them go 10 or 20 years with nothing more than a wisp of ash.

Consider this: With an oil furnace the annual maintenance expense, in my area, is going to be about $115 more than a gas or propane furnace. If we had to park some money in the bank, so that it would generate enough interest to cover the annual service, it would be a chunk of change. Those readers with some finance background might see where I'm going with this: The present value of that perpetual stream of $115 annual payments is quite large. Given the low interest rates today, it would take an investment of $2,000 to $3,000 to generate the $115 annual cash needed.

What's the point of this? It's part of the financial decision to kill the oil furnace and install a new propane furnace. Reducing our annual maintenance costs by $115 is equivalent to having an extra $2,000 in cash right now. When I talked to a local plumbing and heating outfit and heard that new gas/propane furnaces can be had for as little as $800, I was intrigued.

The other problem: When we re-shingled the roof we noticed that the chimney was messed up. I looked down the chimney and I discovered that there was no fire-brick lining or terra-cotta flue tile. Just plain brick. That's not right. Above the roof line, most of the mortar had disintegrated. I re-packed the joints with new mortar and crossed my fingers. I talked to one chimney repair specialist, and they wanted $2,700 to drop a stainless steel flue liner down the 36-foot tall chimney. Just to keep the house eligible for an oil burning furnace. When the oil furnace puked out, I was not terribly upset.

We solved our problems by having a high-efficiency gas furnace installed, which vents through the wall with PVC pipe. Being autumn, the contractor was so busy he had trouble getting a quote to us, so we asked them to just bill us for time and materials. I would be there to help out, help move the furnace into the basement and do any other work needed. Since we installed the new furnace in a different location than the old one (we were no longer constrained by the chimney location) we changed much of the ducting. We provided the supply and return ducting and re-routed the electrical supply. Following the guidance of the furnace installer, I connected the condensate drain pump to a nearby plumbing drain line. The installer only had to connect to the ducts with some minor sheet metal work, install the combustion air and vent piping, connect the propane line, convert the gas valve from natural gas to propane, and do the tuning. In all, he had 8 or 9 hours of labor, at $60 an hour, and the materials amounted about $2,000. For less than the cost of the chimney repair, we had circumvented the need for a chimney, escaped the $115 annual service charge, and got a new reliable furnace. Granted, our costs were low because we did a considerable amount of the work ourselves.

This old house had propane many years ago, for a stove and dryer. But the lines were copper, and too small to provide propane to a furnace. Copper is no longer allowed for lines that run through floors or walls, so we replaced all the lines with 3/4" and 1/2" black iron pipe. This cost a couple of hundred bucks, just for materials, and took several days. We also pressure tested the replacement installation with 30 PSI air pressure for several days (rather than the 30 minutes as required by code) to make sure there were no leaks. The propane company installed a new 500 gallon tank and ran a supply line to the house. They also installed a branch line to the garage, for a future propane heater in the shop. The cost was minimal, about $150.

We are very pleased now that the sulfur-belching oil-sucking dinosaur is gone. The new furnace is quieter and cleaner. Since a gallon of liquid propane has less energy than fuel oil (about 92,000 BTUs versus about 130,000 BTUs for oil) the actual annual heating cost may be slightly higher than with fuel oil. So far, it seems to be about the same, but this winter has been the coldest I've seen while living in this house.

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Written June 2, 2003