Solar Energy - the Economical NorthWarm Version 4 Approach

This system is a smaller and simplified version of the solar heating system I invented in 1974. As is my pattern of insisting on knowing if my calculations and Physics were valid, I insisted on experimentally testing that system, so I also built a modified 1200 square-foot, Chalet-style house in 1974 to confirm that the heating system worked as impressively as the calculations had indicated. It did!

Even though that DIY solar heating system actually pre-dated all of the three other NorthWarm solar heating systems, that version is now called the Version 4 of the NorthWarm Solar Heating system, and a full description of it is presented at NorthWarm Solar-Heated House - Version 4

This new simplified version has eliminated the centrally important heat storage capability (where one full day to a full week of entire house heating was always available, from storage, to ensure coziness and comfort at all times). But the new concept certainly works great, regarding real-time heating!

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People rarely whine any more about the spectacular amounts of used motor oil that is constantly burned (at considerable cost) to dispose of it. In the United States, more than 120 million cars are regularly on the road, and they each should have their motor oil replaced at least once a year (meaning 5 quarts or 4 quarts for each vehicle, more than a gallon), that represents at least 120,000,000 gallons of used motor oil that gets disposed of each year. Actually, substantially more, since there are a lot of trucks on the road, as well, and most people drive enough that they should replace their motor oil twice a year or more often.

I have always seen that process of disposing such an enormous amount of petroleum products each year (by burning, which then causes pollution and more atmospheric heating) as foolish, and even by 1974, I built a house that used a collected 2400 gallons of used motor oil, to use as heat capture and heat storage media. It seemed obvious to me in 1974, and it still seems obvious to me in 2012.

Say that you have an available area on your house roof which is 8 feet by 16 feet, or 128 square feet of area. (Bigger is better!) Next, say that you had some liquid material which was FREE and which was extremely BLACK, that is, it was really good at collecting solar energy. Like used motor oil! And the dirtier the better! Just look at this much so far. On a bright sunny day, more than 300 Btu/hr of solar energy comes in on every square foot. Having 128 square feet of area of very black media, that means that 300 * 128 or 38,400 Btu/hr of heat comes in to the oil. Not all of that heat gets collected, but 36,000 Btu/hr can pretty easily be collected, mostly because it is so black.

To pique your interest, if your house is of medium size and in a cold climate like Chicago's, on the coldest night of February (at negative 10°F outdoor temperature), your house probably loses about 45,000 Btu/hr. Granted that that maximum loss occurs at night when you are not capturing any solar energy, but you can probably already see the central idea of that 1974 solar house I built that was based on using used motor oil! Just this fairly small device on your roof, which is cheap and easy to make, can capture nearly as much solar heat as your whole house loses at night, and certainly more than your house loses during the daytime. Even this simple system can keep your house furnace from ever having to turn on during a sunny day!

Your house roof is slightly sloped, so the hot oil (inside a sealed shallow tank which has a glass top) drains down to the bottom edge, where a (PVC) collection pipe catches the oil and sends it into an (insulated) 1.25 or 1.50" (PVC) pipe or hose. That insulated hose (containing HOT motor oil) goes INTO your house, and it feeds a STANDARD CAR RADIATOR. Next to that radiator is a STANDARD CAR RADIATOR FAN. Since hot oil is passing through INSIDE the radiator, when a STANDARD WALL THERMOSTAT in your house recognizes the need for heat, the radiator fan turns on, nicely hot air is sent into your house! If you have ever been downwind of an operating car engine, you may have experienced the rather hot air which comes away in the NORMAL cooling of a car radiator. In that case, the water in the car radiator is usually around 190°F. In THIS case, the oil that is sent down from the roof oil collector panel might be anywhere between 150°F and 250°F. In any case, the effect is comparable, of creating large amounts of hot air to warm the inside of your home. Once the oil has run through the car radiator, a standard radiator hose takes that oil to a STANDARD CAR WATER PUMP, which recirculates the oil back up to the roof, where it is released through small holes in a PVC pipe along the upper edge of the collection panel.

Notice that the used motor oil is SEALED inside the shallow tank on the roof and inside the radiator and hoses, so NO smell of used motor oil could ever get into your house!

NOTICE THE COSTS INVOLVED A used car radiator, a used car radiator fan, and a used car water pump, which might all come out of an old vehicle you no longer want, or at worst, might cost a total of $50 from a junkyard. Some PVC pipes, some PVC fittings, a couple radiator hoses and hose clamps. Oh, and the used motor oil that a few friends need to dispose of, maybe five gallons of it total, that is, the used motor oil from about five oil changes! It would be tough to spend even $100 for this, but then the waterproof, oilproof roof structure on the roof would require some plywood and some glass. In any case, amazingly low cost!

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A person who is handy should be able to build it all in an easy day, and have a new and FREE and GREEN source of most of his house's heat starting the following day.

At this point you should read and study the Version 4 presentation. That approach includes STORING of heat, which is not done here. In other words, with this non-storing approach, if the sky gets cloudy, no more solar heat is captured! Bummer! But it certainly is simple and easy to do. The Version 4 approach can still be pursued, where the septic tanks for heat storage might be buried in some nearby convenient location.

This approach is not only inexpensive and GREEN, you have a LOT of flexibility regarding adding any bells and whistles you might dream up. Like sending heat to get your domestic hot water ready for showers and baths and clothes washing??? Or a Sauna or a Hot Tub??? You get the point. Actually, heating an outdoor swimming pool also works fine.


Since this system uses used motor oil as the heat capture media, it can operate at any temperatures that car engines operate under, in other words, up to about 250°F, so this system has another possible usage. Consider sending that 250°F heat to surround a small water tank (instead of sending it through a radiator), to therefore produce a lot of steam from the boiled water. Then send that steam into a small steam engine, and have that spinning steam engine spin a car alternator, to produce electricity.

I have not really done much yet about trying to make electricity from this system, but there seems a lot of motivation available for lots of people to buy hobby-sized steam engines (like I had when I was a young kid), to try to see how much electricity someone might make from solar energy. I am confident that many people should be able to figure out how to produce at least 3/4 kiloWatt of electricity (which is about one horsepower), an amount that should be very useful.

This presentation was first placed on the Internet in April 2012.

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C Johnson, Theoretical Physicist, Physics Degree from Univ of Chicago