NorthWarm Solar-Heated House - Version 4

Our other SOLAR heating system Version designs are all very advanced and unique. Versions 1, 2 and 3 are meant for ultimate heat collection and distribution throughout a good-sized house for a relatively normal family. They are extremely effective at accomplishing amazing solar heating at a tolerable cost. This Version 4 is entirely different from those three. It is NOT based on the patent that the other Versions are based on. It is a very LOW-TECH system! In fact, it was invented before any of the others, in 1974, and I then decided to build an entire Chalet-style house to confirm that it worked as I had designed. It did!

We encourage you to look at the web page presentations of the other Versions (especially Version 1). There are links at the end of this page with brief descriptions of the various Versions, so you could visit any of those separate pages. This Version 4 is unique in itself! It can be set up to also provide virtually all the heat needed for a normal home!

Disposing of Used Motor Oil

The Version 4 also represents a wonderful useful purpose for the millions of gallons of used motor oil which must be environmentally disposed of now. YOU actually wind up paying for that disposal cost! Think about it. There are far more than 100 million cars in the US, plus millions of trucks. Changing the oil once a year means at least four quarts of used motor oil, or more than 100 million gallons of used motor oil EVERY YEAR! This Version 4 system can eliminate the need for all that disposal! For my 1974 Chalet-style house of 1200 square foot living area, I bought and installed two 1200 gallon septic tanks UNDER the house, and each SURROUNDED with four inches thick (or R-20) of blue foam insulation. So I used up 2400 gallons of used motor oil, just for that one small house! If around 40,000 such houses were built each year, they could take the 100 million gallons of used motor oil, eliminating any need for trying to safely burn it all! And the house then would have a permanent source of winter heat, for free and without having to burn any fossil fuels or to use any electric heating. It would all be pure and simple SOLAR HEATING (with heat storage in the hot oil in the two septic tanks).

All competing solar heating systems on the market use either air or liquid (usually water with antifreeze) for the heat collection and transport medium. Even our Versions 1 and 2 use air and Version 3 uses liquid. Version 4 is very different and unique. It is designed specifically to use used motor oil!

OK! On first thought, that sounds pretty questionable. But, think about it a little further. You'll see some real benefits from this medium!

For discussion's sake, consider a house like the Chalet-style house which I designed and built in 1974, which has a fairly steep roof and is oriented so that the main roof ridge is east-to-west. This means that there is a large, steep, south-facing area of the roof. Now consider mounting long standard two by fours, on top of the roof, ON EDGE, vertically, from the roof ridge to the eave, spaced 24 inches on center. Next, get or make a bunch of sections of a modified version of metal corrugated roofing. The edges of these pieces are modified in a way to arrange for a final lip outward. The idea is that the piece will fit between the two by fours you attached to the roof, with no possible leaks, with the edge lips resting on the topmost (outermost) edge of the two by fours, to be nailed there. This will vaguely resemble a series of many adjacent playground slides.

We found that the best situation is that the pieces of corrugated metal extended the whole distance from ridge to eave. If a joint must be made, it should overlap at least 8 inches, and have a lot of silicone-caulk sealing the two pieces together. NO nails or other holes should exist ANYWHERE in the trough between the edge rib two by fours. If even a tiny amount of the oil leaked or seeped out, the smell is REALLY obvious and annoying!

ABOVE the oddly corrugated roof, we mounted 1/4" thick glass panels, which were 96 inches high and 23.5 inches wide. The entire roof area was therefore covered with glass. There were two main reasons for this. The glass kept rain and snow from getting into the oil, which tended to cause it to become milky white in color, which would reduce the ability to collect solar energy. (BLACK IS BETTER!) The second was to act as slight thermal insulation, to reduce the amount of captured heat that the oil had, to be able to send more of that heat down into the storage septic tanks. A third reason also applied, that the presence of the enclosing glass surface kept the smell of all that used motor oil from being noticeable!

For the first experimental system we built in 1974, we obtained two very large (1200 gallon) concrete septic tanks, which we put in the crawl space under the house (before it was built). Those tanks were placed on two layers of two inch thick blue Styrofoam, and then two layers of the same insulation was attached to all the outside surfaces of each of the two septic tanks. (This insulation gave about R-20 insulation value.) The tanks then were painted ON THE INSIDE (a nasty job!) with polyurethane concrete paint, to seal the surface from oil seepage.

Then, obtain used motor oil. There are companies that recycle it, but there are also many companies that will give it away to you. You do NOT need to, or even WANT to, clean or re-process it. From our point-of-view, the dirtier the oil, the blacker, and the better! If you use the twin large septic tank reservoir set up like we did, you will be able to put thousands of gallons of used motor oil in the reservoirs.

The Calculations of Why it Works Very Well

The specific heat of most petroleum based products is around 0.50. A gallon of used motor oil weighs around 7 pounds. In our example set-up, we had a total of 2400 gallons of used oil storage, which means 2400 * 7 = 16,800 pounds of oil in the tanks. The specific heat means that 16,800 * 0.5 = 8,400 Btus of heat is stored for each degree rise in the temperature of the oil. With our example, we would sometimes get the storage up to 150°F, which was 80°F higher than the desired 70°F house temperature, so the storage then contained 8,400 * 80 or 672,000 Btus of heat storage. That was essentially enough to entirely heat that whole house for about 24 hours, on the coldest day of a Northern Indiana February. Similar calculations can be done for any size and number of storage tanks.

Next, we got a really heavy-duty (industrial) pump, which was specifically designed to be able to pump viscous liquids. (A 'normal' water pump could move the oil acceptably when the oil was hot, but really strains when it was cold and thick.) That pump was connected so that it could draw liquid from near the bottom of either or both septic tank reservoirs, and it would pump the (black) used motor oil through a large 2" pipe up to an even larger diameter pipe that extended along the entire ridgeline of the house. Many appropriately located, varying diameter holes were drilled in the bottom of that pipe, so that the black motor oil could come out of the ridgeline pipe and down onto the corrugated metal.

On cold days, the oil moved down the roof slowly, due to the cool oil being very viscous, but it gradually sped up as it moved down the roof, as the oil got heated by solar energy. The slow movement of the cool oil was actually a benefit, as it let the oil be exposed to the solar energy for a longer time!

When the oil was hotter, the pump was sometimes taught to not even turn on, if the hot oil in the storage might LOSE more heat than it might gain in each lap of the operation. But if heat gain was likely (known by a photocell that monitored the sky clearness and the sun's heating at that moment), then hotter oil would flow down the roof faster and get back into the storage tanks, just a little bit hotter than it had started out.

The 12-12 slope of my Chalet roof was such that snow rarely accumulated on it overnight, but that even a brief pump operation to send warmer oil UNDER the glass surfaces would liquefy the snow, and often the entire roof surface of snow would slump down off the roof in just seconds.

At the eave edge, a similar large diameter pipe collected the oil after it passed down along the surface of the roof, and then that oil drained (by gravity) back into the septic tank reservoirs. We put a 'connector pipe' between the two septic tanks so neither could overfill or overflow.

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Two layers of standard window or plate glass then covered the entire area of the metal channels on the roof. We found that good caulking and weather stripping was very important, so that there was never any hint of smelling the oil. Also, if even a little rainwater got into the oil, it turns a whitish color that doesn't collect solar energy as well.

The operation of this system tended to allow any water or condensation in the warm or hot oil to evaporate, and we soon had nice black used motor oil again.

The above generally describes the whole concept and the whole system. You probably see some of the way it works. This method has several aspects of real elegance that you might not realize!

On a cool, sunny day, the pump turns on. The oil is pumped up to the ridgeline, and distributed evenly over the entire length of the corrugated collector area. The specific shape of the metal troughs keeps the oil spread out over the whole width of the collector trough, to make sure not to miss any of the solar energy hitting any area. The black oil will absorb a great deal of the heat hitting it, mostly because it's black! By the time this oil gets to the eave area, it is substantially warmer than before, due to the heat it absorbed as it slowly moved down the roof surface. This new, warmer oil drains back into the reservoirs, adding to the heat stored there.

On very cold days, the oil becomes more viscous, and so it flows down the corrugated metal collector areas more slowly. This is beneficial, since it gives that oil some additional time to absorb solar energy. This tends to make it more efficient at accumulating solar energy when it is needed most! On mild days, when all of the oil in the reservoirs is quite hot, the flow is much more rapid, reducing solar heat collection when it is hardly needed. On really mild days, when the storage is as hot as it needs to be, or during the summer, the pump does not turn on, and the metallic surface of the metal will tend to reflect the solar energy, reducing the air conditioning load in the summer.

Being motor oil, there is no danger of it freezing (like water) during very cold weather, so there is no need for a lot of expensive anti-freeze. At the other extreme, there is no danger of the fluid boiling if you start really getting the storage reservoirs really hot. Additionally, this system eliminates society's need for safe disposal of thousands of gallons of used motor oil, thereby benefiting the environment!

Heat For the House

You might have noticed that the system described above NEVER mentions actually heating the house! It only heats the oil in the storage reservoirs! THIS is intentional, because it allows the house rooms to avoid ever being over-heated, which is a common problem with most competitive solar heating efforts. As any room REQUIRES heat, known by a standard wall thermostat, that thermostat turns on a different circulation pump (usually a hydronic pump) and a solenoid valve, which sends hot oil to a standard radiant heater in that specific room. Once that room has warmed to satisfy the wall thermostat setting, it shuts off and that room is never in any danger of being too warm!

There are a variety of ways that the heat can be removed from the storage reservoirs. Since we put the reservoirs under the house, we found that by (automatically) removing some of the insulation on the top of the reservoirs, we could get some heating up to warm the underside of the floor above. We also put several old (ugly?) steam radiators inside the septic tank reservoirs. These very durable, cast-iron radiators are really heavy! But, by using a separate hydronic pump to send water through them, that water would quickly heat up to virtually the temperature of the oil in the reservoir. That water could then be run to normal hot-water radiators in the various rooms of the house. This operation even allowed zoning the heating system of the house, to independently set the temperature of each room! So there is a choice of pumping the non-viscous hot oil directly to room radiators, or of using a heat exchange system to be able to pump water instead.

If a sufficient area of collecting area is used, an amazingly good performance can be had! Our system had about 770 square feet of collecting area. On a nice sunny day, sunlight has about 300 Btu/sq.ft./hour available. This means that we could sometimes collect as much as 230,000 Btu/hr! (There are several technical reasons why it is actually slightly less than this, but 210,000 Btu/hr is very realistic!) During an entire clear, sunny day, more than a million Btus were occasionally collected!

That particular house was moderately insulated, and moderately-sized, in a rather nasty winter climate (northern Indiana), and the house would use up about 40,000 Btu/hr when it was continuously 10 below zero (the 'design temperature'). In 24 hours, that's 960,000 Btu. That means that the half dozen hours of clear sunlight during the day could collect enough solar energy to heat the entire house for all 24 hours of a day EVEN when it was continuously 10 below outside! Even on most February days, it gets up above zero and even up near +30°F briefly, so an entire day's heating needs on the worst days in February is rarely above 500,000 Btu/day. (You won't find anybody else's system that could accomplish that!)

The amount of storage described above can represent as much as 1,500,000 Btu of heat storage (if the oil is at the reasonable maximum of 250°F). This would be enough to maintain the entire house at 70°F inside, for more than two full 24-hour days without any sun when it was -10°F outside! Pretty impressive, huh?

And a realistic week of full heating on slightly milder February days!

The Version 4 System was not really intended as a "total" solar heating system, so we felt that that amount of storage was fine, but larger storage tanks or more of them could obviously increase the storage heat capacity, for larger houses or longer heating capability without sun.

(Actually, our Version 1 system has even far better performance!)

If it was 30°F outside, that amount of storage could likely keep the entire house comfortably heated for an entire week without sun! Of course, installing a third storage reservoir, would improve on even this amazing performance.

When the storage is relative full (the oil is pretty hot), a side benefit of this system is that the hot oil flows down the collector area rather quickly, long enough to gain some solar energy, but not so long that the hot oil would lose much heat by radiative loss while it was in the collector. The glass on top of the collector areas adds to this aspect. It is relatively transparent (about 90%) to the incoming solar energy, but relatively opaque to the infrared heat that would be radiated outward by the oil, thereby keeping most of the heat in the system.

Version 4 REQUIRES a LARGE AREA, properly oriented and sloped roof surface. An alternative might be to build a separate sloping structure near the house. Also required is a person who has good abilities at fairly normal construction.

There are links to the other, more sophisticated Versions of our Solar heating systems at the bottom of this page.

We think that a reasonably adaptable person could build this Version 4 system just from the descriptions above. I certainly built the entire house and heating system in 1974, and it worked excellently. All sorts of improvisations might occur to the constructor, to use locally available materials (like the surplus radiators we used) to assemble the system. Even though we own the invention and the design, we would let people make single systems based on the above descriptions for their own homes. We would NOT permit contractors to build multiple installations without specific written agreements regarding them.

A GREAT consideration in Version 4's final cost is the "handiness" of the homeowner. A creative and handy individual could improvise and construct a lot of the assemblies and structures, possibly even using surplus parts and materials. In such case, the total cost could be QUITE low! On the other hand, if all of the assemblies would be built of list price materials by union craftsmen, the total cost could be substantial!

The saving on heating bills by using this low-tech system ensure that it would pay for itself in just a few years. In the case of our original 1974 system, we found a source for surplus (used) store-front plate glass windows, and we did similar scrounging for the other items, and the total materials cost was not much over $1,000. We saved virtually that much each and every winter, so it quickly paid for itself. After that first winter, further savings were just gravy! All this suggests that there are a couple additional values involved. First, the security of KNOWING that the house will be fully heated regardless of political events in the Mid-East or decisions of executives or politicians that might affect fuel supplies or prices. Second, given these things, the property's VALUE would probably be increased more than the cost of the system, because MANY people would want a home with such security.

The design is NOT based on exotic glass or exotic materials or insulations in collector panels, so there is no mumbo-jumbo arguments about having to use high-emissivity glass or other advanced subjects. The usage of special "solar" glass WOULD improve the system performance, but not enough to counteract the MUCH higher price of those kinds of glass. This Version 4 is based on a VERY LOW-TECH approach, where expensive, exotic components are not necessary. Standard 1/4" plate glass and other standard materials are generally used. With the very large collector area, we feel the logic of the system is obvious. Large collector area = a lot of heat collected. Large storage tank(s) = enough heat for a substantial house for a good number of hours. It's all actually pretty simple in concept.

Free Air-Conditioning???

We have even decided to present one of the sub-systems of the Version 1 system, as a separate presentation. It only represents about 10% of the effectiveness of the Version 1 system, but we realize that it can have separate applications on its own. This portion of the Solar system is involved (in winter) in providing "make-up" air for the house. Our approach greatly reduces the (winter) heating load of the whole house system, and, as a bonus, also can provide (in nearly all climates) virtually FREE air-conditioning for the whole house! As indicated, we realize that this sub-system could have many applications in existing houses, so we have a page that Home Air Conditioning - and More! presents this intake system separately. In a similar way to our freely offering this information on the Version 4 heating system, we present sufficient information in that presentation to assemble the free air-conditioning system, also at no charge.

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The other Solar heating systems:

Not Us!

Finally, if your needs and requirements are for limited solar heat gain, none of these Versions makes much sense. If your desire is just to heat your domestic hot water, or to reduce your heating bill by 10%, these are probably not the way to go! There are a multitude of companies that make collector panels that you could slap on your roof for such applications.

We have no intention in trying to "cut in" to the market for such products! Each of the four Versions (especially Version 1) is intended and designed and engineered for SERIOUS solar space heating; situations where no competitive technology exists that can do the job!

SO, for the multitude of people who read about the Versions, and then ask us to supply them with something that might go on their roof, they're barking up the wrong tree! The only Version that could possibly be applied to an existing roof is (this) Version 4, by far the least sophisticated and efficient of the four! And, even then, the Version 4 system involves far more than just nailing some panels to a roof. So, please realize that these Versions are NOT competitors to those available roof panel systems. We actually have no competition at all, because no one seems to know how to ENTIRELY and COMFORTABLY heat a home exclusively with solar energy. Except us!

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