Kerosene Heat — Old-fashioned Warmth Improved

sengoku kerosene heater

The Sengoku OR-77 is now in it’s sixth winter.

Last night about midnight I was out picking tomatoes and chili peppers because it felt like a frost coming. It’s actually the third time frost has been predicted here but I let the first two warnings skim past me. This time it felt like the real thing, and it was. Today I’ll be making pickled green tomatoes and I already dug out the kerosene heater for when I really do need it.

I’ll be using the Sengoku OR-77 HeatMate Kerosene Heater more often this winter. Up till now I kept it for emergency heat when the power goes out. Yesterday I checked heating oil prices and yikes, looks like I need an alternative. If the people who built this house had known what was coming they’d probably have gone with something other than a fuel oil furnace.

Updating 11/29/2011: Today the outside temperature is 35, there’s a good north wind blowing, and it’s raining. Ack. This morning I thought for my mental health I should fire up the heater indoors for the first time and see if it’s a viable alternative to adaptation and more layers of clothes. In about 1,000 square feet of space with a window opened slightly for ventilation (a lifesaving practice so don’t skip it) the Sengoku OR-77 Heatmate Kerosene Heater raised the room temperature 7 degrees in one hour, in spite of the tinkering I was compelled to do to it. A few days ago I did a test burn outside on a nice day, and for the first couple of minutes the protective oil and wax on the burner parts sent up a plume of thick black smoke, as the manual mentions. I did not do the 30 minute burn the manual recommends because the fumes vanished in minutes. In the house I had no problems, the heater ignites with the push of a button and the flame adjusts easily. You might be tempted to set the burner too low — a correct setting heats the entire radiant grid cherry red and any flames licking out the top should burn blue. The camera shows the grid brilliant white but it’s actually glowing red. If the tips turn yellow or the grid only partly heats, it’s not quite right. The only time I noticed kerosene smells were for a moment after turning the heater off. I’m very pleased with this little heater.

Kerosene costs a little more than fuel oil, about fifty cents a gallon more here in Indiana if you buy from a gas station like Speedway or Gas America. The best kerosene comes in cans, and if you want to pay double the gas station price you can get it that way at places like Lowe’s or Tractor Supply Company, in one or five gallon cans. It’s K-1 kerosene whether you get it from the tank at the Speedway or the shelf at the hardware store, but in cans you get kerosene without any water in it. The gas station version comes from an underground storage tank and there’s a little condensation down there, so there’s always a little water in the fuel. You’ll have the same problem if you try to hold over some fuel for next winter. If you do that, fill up the kerosene container to the safety line so you don’t leave inside walls exposed. Kerosene stores without degrading for up to five years, in a full, sealed container.

Water settles to the bottom of the fuel tank, and modern kerosene heaters avoid drawing those water droplets up by separating the wick from the bottom of the tank with a central wick well. You won’t be able to burn the last half inch or so of fuel but you also won’t be drawing up the water at the bottom of it. If the water gets into the wick it doesn’t flow up and out, just stays in the wick and blocks the movement of the kerosene. Eventually the wick waterlogs and the stove won’t light. I used to recommend using 100 percent isopropyl alcohol to remove the water, and everyone said it would draw the water up through the wick and burn it off. I no longer recommend using any alcohol fuel treatment because I’ve noticed that the more of it I use the faster the wick waterlogs. I researched why this is, and it’s because products like HEET were designed for clearing water from the fuel systems of internal combustion engines. They were not designed for kerosene heaters no matter what you might read on a label in Walmart. Internal combustions engine fire off the alcohol/water mixture, converting the water to steam and expelling it through the exhaust. Wicks don’t do that. Alcohol draw water into the wick and then the alcohol burns off. The water stays there.

Unless you buy the very expensive canned pure kerosene, you’ll be getting fuel from the kerosene pump behind the gas station like I do. Because this cheaper fuel does have some water included, I’m using a water filter funnel to clean the fuel before it goes into my stove. Mr. Funnel works very well for me, but I recommend trying to pour water through it before you risk your heaters with it. Mine worked fine the first year, blocking the water and letting the fuel pass through, then the next winter I had trouble with the heaters again. Finally I thought to water test Mr. Funnel, and over the summer something (perhaps mold) had ruined the filter membrane. Mr. Funnel was leaking water. So I ordered a new Mr. Funnel and will come up with a better storage system for him in the off season.

heating oil price graph

The good old days are shown to the left.

There are other tricks to running a 10,000 BTU kerosene heater in your front room. You can’t burn anything but kerosene in it, so don’t experiment with gasoline and don’t store kerosene in an old gas can. Even the little bit of gas in an “empty” gas can unwisely used to store kerosene flows to the wick first and makes an interesting and very dangerous explosion when you light it off. Kerosene won’t explode, but people still manage to burn their houses down with it by trying to fill the stove while it’s still in the living room. Some people think they can do that safely with the stove lit, too. Well, you can’t, and all it takes is one slip and you’ve set your living room on fire. Take the stove outside and fill it there. The Sengoku OR-77 includes a nice metal handle for hauling it in and out of the house.

This old-fashioned heating system needs frequent tending, but not quite so much as a wood fire. The top section of the wick doesn’t burn, because it’s a permanent fiberglass wick, but it does clog with tar and harden. After a few tanks of fuel go through it you need to do some maintenance by letting it burn empty and brushing the wick clear of soot. Break up any hard spots carefully by squeezing with a pair of pliers. If you don’t do this the wick gradually stops working.

If you set the wick correctly and use new K-1 fuel, you get a nice blue flame that burns cleanly and produces a minimum of combustion byproducts. Set the wick too low or too high and you’ll get another color, like yellow, and the stove produces smoke. Faulty settings also increase the carbon monoxide production, something that’s always going to be there but in manageable amounts if the stove works right. You can’t run a kerosene stove in a closed room, for the same reason you can’t run the exhaust pipe of your car into the passenger compartment or seal yourself up in a plastic bag. Both you and the stove need fresh air. Open a window a minimum of one inch. Pick one on the lee side of the house so you don’t get a constant blast of north wind. If you have the stove in a different room, keep doors open to the room with the partly open window.

At first, years ago when I wrote this article, I thought that as a constant heat source, kerosene stoves suck pretty badly. That’s because of my experiences with the emergency kerosene heater my father bought back in the 50’s when soot and fumes and cigarettes were considered healthful additions to the home environment.  It’s much like a wood fire in that the room will either be too hot or too cold, but I have learned to adjust with clothing. Sometimes in the coldest of the winter I find myself standing in front of the window with a cup of tea looking out at the snow and the wind and the people staring as they drive by, and then I realize I’m dressed sensibly in wool pants with long underwear, a warm shirt, a sweater, and a Polish Army Greatcoat plus a wool beret. Probably looks odd to the people who pass by, but it’s comfy.

You can’t lower the wick to produce less heat, because the wick only burns efficiently at the one setting, the one that creates an even blue flame. With a kerosene stove, you control the room temperature by turning the stove on, and then turning the stove off. The Sengoku OR-77 uses an electric igniter that makes lighting the stove simple. Two D-batteries heat a small electric filament that lights the stove. You can also use a match. Get used to turning the stove off as much as possible and don’t ever leave it burning at night.

In mild winter weather it’s economical, but when the temperature drops far enough to require constant heat in the house, you might think the old oil furnace still makes better sense. I jumped up instead to a Sengoku CV-23K with twice the heating power.  I don’t need to run it as long to get the house to pleasant heat levels, so it isn’t really more expensive in terms of fuel. I do need to pay attention to ventilation and make sure the one window is open an inch. Even with its limitations, a kerosene stove is a nice backup system to have around and can save you a lot of money if you use it wisely, which is not much. Run it enough to take the chill out of the air and then shut it down. I have used it for seven years now and have not had to use the oil furnace once since I started this. It’s heat you can actually back up to and get warm.

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About JTHats

Avid backpacker and outdoorsman with old skills and interests in old ways of doing things; equally fascinated by electronics, from the days of Sputnik, to the Zilog Z80A, to the present day of black box circuitry. Sixty years of experience with growing my own food and living simply. Certified electronics technician, professional woodturner, woodcarver, and graduate of two military survival courses -- Arctic and Jungle.

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