Flying High on Solar

Tom Simko

©1993 Tom Simko

Seventeen years ago I moved onto my piece of ground. I was living in a fifth wheel trailer I'd built, and running the lights and a radio off my pickup's battery via jumper cables. The 20 mile drive into town recharged the battery enough for the next night's use. This worked fine the first summer and fall. During my first winter, I had no way of keeping my driveway plowed. I was often snowed out and had to park on the side of the county road. My place is at 6150 feet above sea level, and a ski area is a half mile away, so this should not have been a surprise! After finding that jumper cables are not readily available in 700 foot lengths, I decided an upgrade in the power supply was an urgent matter.

Road Trip (or How I Got Here)

In 1974 I was traveling throughout the West in my home built motorhome. I had everything I owned with me: all my carpenter tools of the trade, and two hang gliders on the roof. I had started flying in 1972 while living in Big Sur, California. I embarked on an "Endless Summer" sort of trip looking for hang gliding sites. The sport was new then and most of the mountains I was flying had never been flown before. I was picking up enough work to get by, and having lots of adventures along the way. At one point I took a vacation from this grueling grind, and a friend and I spent three months traveling abroad. Back in the States, I started looking for a place to settle down between trips. I found it when I first saw the Portneuf Range, located 20 miles south of Pocatello, Idaho. The range faces the prevailing wind and there is almost a 5000 foot vertical drop from the peak of 9260 foot Bonneville Peak to the valley below. It is a hang glider pilot's paradise, and I got to know the resident hawks and eagles on a first name basis in the years I flew gliders. Now I fly ultralight and experimental aircraft from my small airstrip (okay, it's my driveway). But I can still power up to the peak, shut the engine off and make like a bird, and I don't need a 4-wheel drive to get up the mountain anymore!

Early Power System

I received a bid of over $10,000 from Idaho Power to run lines to my place, even though the existing line was only a quarter mile away! The ski area had recently paid to upgrade the line up the mountain and I would be paying extra to share the costs. Not!!! It was sort of a kinky thrill, telling the service rep, "Thanks, but no thanks." The lines would have made flying out of my driveway impossible (burial would have been even more money), and besides, I had wanted a windmill for a long time. Now I really had no choice — no way could I come up with 10 grand.

I built a 30 foot wood tower and erected my first wind machine, an antique 6 Volt, 200 Watt Wincharger. Charging at 6 Volts while using 12 Volts was awkward, but two sets of batteries made the system workable. I get a lot of wind in the winter, and even this small mill was a major improvement over the jumper-cables-to-the-truck system.

During the next few years I rapidly upgraded my power production to keep pace with my increasing demand. A 12 Volt Wincharger was my next machine and a 500 watt Honeywell rotary inverter supplied my first ac power. Next was a quantum leap in power production, an old rebuilt 32 Volt, 1000 Watt Wincharger. Steve Hicks of Mountain Pass Wind in Montana was a big help. He sold me some of the machines and supplied parts. I had also found a 1500 watt rotary inverter. Charging four batteries at 24 Volts and then rigging them to put out 12 Volts for the inverter was a pain, but it worked. I needed the ac power because I was starting to build my shop.

Shop Talk

I built my shop using lumber salvaged from a building I'd torn down. The shop stands 32 feet by 40 feet with a 14 foot high ceiling. My shop is insulated to R-60 in the ceiling and R-27 in the walls using fiberglass batts from a demolition job. It has a full bathroom, large south facing windows, and below-grade foam foundation insulation. The temperature has never dropped below 45°F since I built it, even when not heated and during extended cold spells. I lived in it for 5 years after I got rid of the trailer. As I am a carpenter and a master at scrounging building materials, I have less money in it than most people have in their new pickup trucks! I use it for my construction business and for building and working on various aircraft.

What is thermal mass and where can I get some?

While living in my trailer, I noticed that even though it was well insulated (for a trailer anyway, R- Below: 11), soon after the wood stove fire went out, the temperature quickly dropped to almost the outside temperature. I had no thermal mass to store the heat. As an experiment I filled some 15 gallon drums with water and positioned them around the rear of the stove. The idea was to store some of the heat and moderate the temperature swings. It worked and lead to my shop heating system.

The heart of the shop system is a massive wood fired boiler called Big Bertha. Bertha has a four foot long firebox, two feet in diameter. The firebox is surrounded by a three foot diameter water jacket except for the front. I burn scrap lumber and wanted to cut down on the cutting. I can cut a forklift pallet in half and Bertha will make it disappear.

I made Bertha out of scrap 12 inch wall pipe; it weighs over 500 pounds empty. The firebox uses outside air for combustion, which is drawn in through a three inch diameter pipe in the top, thus preheating it. For an extra hot quick fire I have the option of Turbo Mode, a small squirrel cage fan. The fan is also useful in starting a fire — no need for kindling.

The water jacket holds around 60 gallons of water which weighs 480 pounds. As this water is heated, it thermosiphons through two inch copper pipe, six feet into a 500 gallon tank. The tank is made of 12 inch thick steel and weighs 1500 pounds empty. The water weighs 4000 pounds. Now we are talking thermal mass! The tank is in a super insulated enclosure.

Inside the tank is a 60 foot coil of 34 inch copper tubing that has a glycol mix that circulates outside into three 4 foot by 10 foot solar thermal panels. A 10 Watt photovoltaic (solar electric) modules powers the 10 Watt pump. An expansion tank allows for pressure changes. The three panels will raise the 500 gallons of water about 15-20 degrees a day during the winter. Even on a cloudy day they help to offset standby heat loss. The panels are angled for maximum production during winter. An eight gallon tank sits in the 500 gallon tank and preheats water used in the shop bathroom.

A small circulator pump below the storage tank sucks the heated water down through a 1% inch copper manifold and then throughout the five inch thick concrete floor slab via the "Twintran counter-flow energy transfer hose with 02 barrier"™. The water then returns to the tank and completes the cycles. The heat transfer hose is special rubber (looks like air hose) that the concrete floor pours right over. Twelve 120 foot

: Tom at his shop working on a Kitfox experimental aircraft.

tubing circuits go to each manifold. Thus heat from the water is transferred to the slab. The slab weighs 77,000 pounds. Adding the weight of the boiler and water, the tank and its water, and the floor slab, we now have a grand total of 83,480 pounds of thermal mass. Once this comes up to temperature, it takes more than an open window to cool things off.

During the winter, on clear and sunny days (lows about 10 degrees and highs 20 or 30 degrees), I can keep the shop in the 60's through a combination of solar passive gain through the windows and hot water made by the panels and pumped through the floor. This is a great working temperature for a shop, and seems warmer because your feet are warm! Plus the heat does not stagnate at the ceiling. When I had a small sleeping loft near the 14 foot ceiling, tests showed the floor temperature at 70 degrees, six feet up was 68°, and up near the ceiling measured in the low 60's. Slab heat is a much better use of the heat and much more comfortable to boot!

During cloudy or really cold weather, I stuff Bertha full of plywood scraps, 2x4's and other wood waste and let 'er rip. I'm not interested in a low, long-term smoldering fire, I want a hot blazing efficient fire to really heat the water. I usually start a fire every other day. Only in below zero stretches do I need to fire up every day, and these are rare. I also have the convenience of starting a fire in the morning and using the heat at night. Try that with a conventional wood heater! The boiler is uninsulated so even though most of the BTUs go into the storage tank, it still throws off a lot of heat. The shop system gave me some valuable experience in radiant floor heating systems and I knew I wanted a similar setup in my house.

Big Jake and yet another demolition job

Once firmly ensconced in my shop/hangar/apartment I started to need yet more power. (I had built a Kitfox, a folding wing mini bush plane, and stored it right next to my living area in the shop, along with my pickup.) I had bought an old 1952 two cylinder Onan generator that put out 30 Amps at 40 VDC, and was using it maybe four or five hours a month. That was four or five hours too much, in my mind. When I saw an 1800 Watt Jacobs wind machine in the local paper for sale, I decided to upgrade again.

A 40 foot, four legged tower came with it. I reassembled the tower and partially rebuilt the Jacobs. Two hours with a boom truck served to place the tower and then the mill on top. My old wood tower location left something to be desired aerodynamically speaking. The new steel tower was higher and on a better part of my property, much more out in the open. The old wood tower had served me well, and with due respect was fed to Bertha the next winter.

I had recently got a free set of 36 Volt forklift batteries, 1500 pounds worth. So my 32 Volt system mutated into a 36 Volt system. By now I had many shop tools including the usual carpenter small power tools and worm gear saws, and in addition, a DC powered metal cutting bandsaw, air compressor and drill press. I also have ac grinders, radial arm saw, and small table saw. The old rotary inverter was next to go. I'd been hearing about these newfangled solid state inverters with incredible efficiencies. After purchasing a 36 Volt Trace with Turbo Cooling and low voltage cutout, I was sorry I'd waited so long. The inverter made a huge difference in how I used my power. Now I could run small appliances and tools and not have the inverter gobble up more power than the load!

Left: Big Bertha the wood fired boiler, heats the shop and water. Above: The heat transfer tubing before cement slab.

Hot Water System

Hot Water System

Building the House

Shortly after this latest addition to the system, I came across the opportunity to demolish a huge wood framed building for a share in the useable wood. We're talking 100 feet wide by 300 feet long, two stories and all built with good old growth lumber — the kind you can't get anymore! There was also lots of structural steel, hundreds of feet of 3 inch aluminum conduit, long runs of heavy electrical cable, and thousands of feet of steel pipe. A year and a half of hard work later, I had completed my contract, made a good living during that time, and had a huge stack of the very best material in the building. This represented a small portion of the total, but it would be more than enough to build my house.

A good carpenter can visualize the finished project, work every day, and not really need a set of prints to build from. I had certainly done my share of this, but I decided to build a 1 inch to the foot model first. This was a real help in positioning windows and roof overhangs as I could take the model outside and see how the sun and shadows interplayed. I even did wind tunnel tests to see how snow would drift around doorways. As a result, my windows are all shaded in the summer, while all winter I get lots of free heat. The tricky part was designing to the materials I had available. Luckily everything clicked and after years of daydreaming about my future house, designing and building the model took one week.

The house, like the shop, is insulated to R-60 in the ceiling, and R-27 in the walls. All sub-sheathing for the walls and roof is 34 inch plywood. The daylight basement framed portion is built with 2x8's for studs. There is over 200 feet of 10 inch I-beam and lots of six inch pipe in the framework. All floor and roof load factors are in excess of even commercial codes, and it all cost me less than another new truck! I have 1900 square feet on three levels, with three bathrooms (all with low flush toilets and low flow faucets). The concrete foundation walls are insulated to R-10 on the outside with rigid foam insulation, then stuccoed. The house is wired conventionally, with the exception of a small 12 VDC circuit for a backup for lights and my Sangean ATS-803A all band radio if the inverter goes out. All ac power, water, phone lines, and compressed air are buried in a utility trench going to the shop, 80 feet away. The batteries and inverter are in the shop.

During construction my air compressor in the shop supplied power for my air nailing guns, while the Trace ran my big 15 amp Milwaukee worm gear saw and other tools with no problems. The Jake would usually keep up with all these demands for power, but during extended calm periods in the summer I had to run the generator for an hour or two.

All of the structural steel, and the hundreds of feet of pipe making up the deck handrails were welded with a 36 VDC welder that was purchased from Bob McBroom of Kansas Wind Power. It was originally an accessory on a DC powered line of garden tractors made by General Electric. I have welded up a storm ever since getting it five years ago. Projects include a 16 foot all steel trailer, several truck beds, and all kinds of shop projects. The house welding was mostly X inch and thicker steel, and on a good windy day I could burn through X inch material with no problem.

Heating the House

On the main floor of the house, I poured a 2X inch thick concrete slab directly over my wood subfloor and the heat transfer tubing. The subfloor was insulated on the backside with foil-faced R-10 insulation. The tubing is

Where the Hot Water Bucks Went

Shop Hot Water System Equipment

Cost

%

Heat transfer tubing (in slab)

$450

23%

Three 4x10 foot solar panels

$450

23%

Big Bertha boiler

$325

16%

10 W, 12 V Panasonic pump

$165

8%

copper pipe & misc. valves

$150

8%

24 VDC March circulator pump

$115

6%

10 W Solarex panel (for pump)

$110

6%

500 gallon tank

$90

5%

Insulated enclosure for tank

$80

4%

Three gallon expansion tank

$40

2%

Eight gallon aluminum tank

$10

1%

Subtotal

$1,985

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