PREPPER PROJECTS

SOLAR

I t’s not hard to find plans, videos and how-to instructions for making your own solar water heater. And while most of the designs that litter the internet do produce hot water, most are also junk. That’s because they’re clunky, mickey mouse contraptions that are more about backyard tinkering than meaningful hot water production in a survival situ-

ation. Most don’t generate enough hot water to make a difference in your life, and most certainly can’t function below freezing. Even a black bucket filled with water outside on a sunny summer day will warm up. Big deal.

Build an evacuated tube collector system and harvest serious heat in any climate

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CONVERSION LOSSESOne of the main things to understand about energy is how

much is lost every time you convert from one form of ener-

gy to another. When you drive your car, for instance, you’re

converting chemical energy (in the form of gasoline), into

kinetic energy (in the form of a moving vehicle). For every

100 units of energy you put into the gas tank only about 25

units shows up as movement. The other 75 is lost as heat

and that’s what they call a conversion loss. Something simi-

lar happens when you run a power tool. For every 100 units

of electrical energy that is drawn by your table saw, perhaps

50 units ends up as movement in the spinning blade. The

other 50 is lost as heat – another conversion loss. The rea-

son grid electricity will always average out to be an expen-

sive way to heat is because so many conversion steps (and

conversion losses) are involved in creating it. For example:

Chemical energy in the form of coal is burned to make heat

that boils water to spin a turbine in a power plant. The kinet-

ic energy of the spinning turbine is converted to electricity

by a generator. This electrical energy is transmitted over the

grid wires (losing energy as it does), and this electrical ener-

gy is converted back into heat by a baseboard heater along

the wall. With roughly a 25% to 50% loss in energy at each

step, the ineffi ciencies of this scenario is huge.

All this is why solar heating technology makes so much

sense. There’s only the simplest of conversion steps in-

volved (solar energy directly to heat), and it’s clean, simple

and involves few moving parts.

If you take survival prep seriously, you need a system that produces many gallons of steaming hot water each day for faucets and space heating. You’ll also need that system to work for you reliably and under the harshest conditions. This kind of success involves more than snaking a hundred feet of black pipe on your roof and giving yourself a genius rating. You need a solar collector that works in a world that’s sometimes both cold and hot, you need to understand how to connect that collector into a system that keeps your house warm and hot water fl owing from taps, and you’ll need to be able to troubleshoot and modify your set up when there’s no one there to help. This Prepper Project gets you started in all this and more.

Evacuated Tubes: The Big-Gun Solar SolutionThere are two main types of solar heat collectors in the world: fl at plate and evacuated tube. Flat plate systems have been around for more than 100 years and they work well. Heat collecting liquid fl ows past an absorptive collection material, picking up heat developed on the surface of the fl at plate as the sun shines on it. Flat plates are great and we could have built this Prepper Project around them. But there are two reasons we chose to offer you an evacuated tube system.

The fi rst is high-temperature effectiveness. Evacuated tube solar collectors are the nuclear reactor of alternative energy systems. They collect so much heat they can boil water even on the coldest days. They also keep on working for decades and the tubes themselves have no moving parts. Evacuated tubes are available alone or as part of ready-made systems you can buy and hook up to energize your hot water system. Flat plate collectors gather solar heat more effi ciently than evacuated tubes at lower temperatures, but at the 140ºF to 185ºF temperatures we want our water to be for heating, evacuated tube effi ciency pulls ahead, especially in areas that get colder than 50ºF.

Solar BasicsBefore you get ready to build your system, the fi rst thing to understand is that solar water heating is all about just that. Solar water heating. Except for one emerging exception that I’ll tell you about later, I’m not talking about making electricity here (that’s called photovoltaics); nor is this Prepper Project about heating air with the sun. Heating water (or some other heat transfer liquid) is what we’re aiming to do. This water can then be used for space heating or domestic use at faucets.

Another thing to understand is how much energy comes from the

sun. You never get something for nothing in the world of energy, so it’s vital that you have some sense of how much heat you can expect to get for a given size of solar collector.

If you went into space just past the earth’s atmosphere and held up a device to measure the total amount of solar energy hitting that spot,

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3” x 8” – 20 to 40 plateheat exchanger

evacuated tubesolar collector

cooler glycol solutionreturn from heat exchanger

hot glycol solution supply from collector

solar controller display

solar controller

insulated pipeassembly

valves allowpump to be isolatedfor pump replacement

INDOOR SPACE

OUTDOOR SPACE

collector temperature sensor wirecirculation pump wirepower supply wirewater tank temperature sensor wiredisplay wire

water preheated by solar before entering water heater

hot water supplyfrom tank for spaceheating and domestichot water

variable speedcirculator pump

propane hot water tank

cold watersupply to tank

open valve to by-pass heat exchanger

exhaust stack

propane burner does notcome on as long as solar collector delivers hot water to tank

EVACUATED TUBE SOLAR COLLECTOR SYSTEM

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INSTALLATION CAREBeing glass, evacuated tubes are obviously fragile. But as

you install an evacuated tube solar collector, there are two

hidden dangers you need to be careful about. First, keep

the installed collector shaded before putting it into service.

A dry collector or a collector without water circulation can

be damaged by excess heat. And second, when you do fi ll

the collector with liquid, do it when the sun is weak or the

collector remains shaded. Putting cold liquid into a hot col-

lector can cause the glass to break – not a good start to

your solar water heating lifestyle.

your meter would read something like 1367 watts per square meter. This number is called the “solar constant”. It’s impressive, but don’t get too excited. By the time that same infl ow of energy reaches the earth’s surface, we’ve lost roughly one third of the power. The very best we can hope for on the surface of the earth is 1000 watts per square meter, but only on a clear day with the sun directly overhead. In most latitudes you’re looking at less energy available to harvest, and the further from the equator you get, the less solar energy hits the earth. Weather and days of sunshine have a big effect, too. Tuscon, for instance, gets almost 2 1/2 times more average solar energy per day than Chicago.

There’s one more round of losses before we get to real-world numbers. There may be nearly 1000 watts per square meter hitting the pavement at noon in Miami, but no collector in the world can convert all that solar energy into heat. Effi ciencies are always less than 100%. In practice you can expect roughly a 30% effi ciency rating from an evacuated tube solar collector. Flat plate systems might be 50% effi cient under ideal situations depending on how you calculate it.

The bottom line in all this is simple: Solar heating is viable, but you need to be smart to get real gains. And this means using the right kind of equipment.

System OverviewThere are fi ve main parts to our solar heat collection system:

1. Evacuated tube solar collector This converts solar energy into heat energy in the form of hot water. The evacuated tube collectors are the fl ashiest part of the system and work like magic. Highly insulated thanks to a built in vacuum, evacuated tubes work especially well in cold climates or where high water temperatures are the goal.

2. Hot water transport system A system of insulated pipes moves the hot water away from the collector to a place where the hot water is useful inside a building. Insulated pipes seem simple, but they’re often the weakest link in solar heating systems. The best systems are waterproof on the outside, as you’ll see.

3. Heat exchange systemCirculator pumps and heat exchangers transfer the heat from the hot collector liquid to hot water running out of your taps or heating your buildings. Direct connections are almost never done for reasons that’ll be explained later.

This is a fl at plate heat exchanger shown to the left. About 12” tall, this model can transfer thousands of btus of heat from a solar collect to water heating your home or domestic water supply.

4. Temperature control systemThis is the system of thermostats, sensors and valves that controls the fl ow of hot water and maintains a steady room temperature. For best performance, special controls work best with hot water heating systems. More on this coming up.

5. Backup heating systemSolar energy isn’t constant enough to deliver reliable heat and hot water except in very warm and sunny climates. That’s why some kind of backup heating system is necessary. Choosing the right kind can make a big difference in your survival success. On-site energy resources is one key feature.The backup unit shown here to the left is a gas-fi red, tankless water heater. There are good reasons to consider a propane system as a powerful backup energy source.More later.

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SIZING YOUR SOLAR COLLECTORThe output of your evacuated tube collector should match

the volume of hot water you expect to consume. Besides

costing more than necessary, too large of a collector is in

danger of overheating. So how big should you make your

collector? A rule of thumb is that one 6-foot long evacu-

ated tube will heat about 2 1/2 gallons of water from 50ºF

to 120ºF. The number of tubes you have should match how

much heat or hot water you need. Depending on where you

live, and how much your household heat demand varies, you

may need some mechanism for protecting the collector sys-

tem from overheating beyond what you get with proper siz-

ing. For more on this see “Overheating Protection Options”

on page 7.Part 1: The Evacuated Tube Solar CollectorThink of these tubes like glass thermos bottle liners. The inside layer is coated glass to absorb solar energy; clear glass is on the outside to create a space; and a nearly perfect vacuum exists between these two layers. Why a vacuum? The absence of air is an excellent insulator, so it allows high levels of heat to develop inside the evacuated tube, even in winter. The vacuum is why these are called evacuated solar tubes and they’re the best for non-tropical climates.

The emergence of evacuated tube technology is responsible for the largest improvements in solar heat collection during the last 30 years. First developed in the early 1980s at Qing Hua University in China, this country is still a world leader in evacuated tube manufacturing. Smooth, dark tubes are lined up side by side in the overall collector, and the heat they produce is transferred to liquid that’s stored in a tank and used to heat buildings or domestic hot water.

There are two ways you can get evacuated tube collectors working for you. You can buy a ready-made array that’s all set for connecting to your system of pipes, pumps and tank; or you can buy plain evacuated tubes and work them into your own array, support stand and system. Here are some specifi c product options we recommend:

Bare Bones Tubes: Clean Republic 10-Pack Evacuated Tubes Nothing but double-walled glass tubes here, closed at one end. Cost is minimal, but you need to create your own angled mounting rack and plumbing connections to move water or anti-freeze liquid in and out of the tubes. Inexpensive, but only makes sense if you’re technically experienced and mechanically creative. One way to use plain evacuated tubes is to insert a metal heat pipe tube inside each one. Heat pipes are hollow, sealed copper pipes with a low boiling point liquid inside. One heat pipe sits inside each glass evacuated tube, with a bulb extending out the top. The heat pipe delivers heat to the top of each tube where it can be conducted to a fl ow of water. The Clean Republic tubes are not eligible for government tax rebates because they’re not part of a system that can be tested. But at $110 for ten tubes, they’re perfect for low-cost tinkering. Copper heat pipes are available from various manufacturers and cost $6 to $20 each, depending on length.

Ready-Made Array: Duda 30-Tube Evacuated Tube Solar Water Heating SystemOne of the best systems around made by one of the most experienced equipment suppliers. This model has evacuated tubes mounted on a metal frame, all connected together with a manifold. Meets SRCC certifi cation standard OG-100, this collector is eligible for a 30% federal tax break. Additional tax breaks may be offered in your state, too. Produces 30,000 to 45,000 btu/day depending on how much hotter the water is than the surrounding air. Ideal for a pressurized system as shown on page 3. $1250.

Passive System: Blueclean 24-Tube Non-Pressurized Water HeaterThis unit has an insulated, on-board, stainless steel tank for storing the hot water produced by the evacuated tubes. Takes about 3 hours to raise water to the boiling point under ideal conditions and holds heat for about 3 days. Ideal for pump-free circulation to a non-pressurized holding tank mounted higher than the collector. Three year warranty. $1200

PRESSURIZED VERSUS NON-PRESSURIZED SYSTEMSPressurized solar water heaters have a closed loop of pipes

connecting the entire system that fl ows through the evacu-

ated tubes. Pressurized systems are what you want for de-

livering heat to tanks in neighbouring buildings for domestic

hot water production or space heating. Typical operating

pressures run from 5 to 20 psi, making it easier for pumps to

perform effi ciently, especially at high water temperatures.

Non-pressurized systems are simpler because they use no

pumps. Instead, heat is transferred to a neighouring open

tank by thermosyphon action.

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WHY YOU NEED A CONTROLLERSolar thermal con-

trollers are necessary

for any pressurized

heating system that

includes pumps and

valves. Controllers

take input from tem-

perature probes on

the collector and tank,

then operate valves

and pumps depending on conditions. When your so-

lar collector is cold on a winter night, for instance,

the controller shuts off water fl ow until the collector

warms up again. And on a bright sunny day the con-

troller might sense an overheating collector and ac-

tivate a valve that directs hot water someplace safe.

Control System: TK-SC6 Electronic Solar Water Heater ControllerA solar controller is the brains of any pressurized, pump-equipped system, and this model has features that make sense in the real world. It comes with three temperature sensors – one for the top of your storage tank, one for the bottom of the tank and a third for the collector itself. Able to switch electrical loads up to 600 watts without a relay, that’s more than enough to handle a circulator pump and electric valves. A proven track record and a reasonable price. $125

Part 2: The Hot WaterTransfer SystemIt’s one thing to produce hot water in evacuated tubes, but you need to move that hot water around to make it useful. This is where insulated pipes, pumps, valves and controllers come in. And of all these components, insulated pipes are the most overlooked. They’re very important but not very interesting.

The water that fl ows from an evacuated tube solar collector can easily run from 150ºF to 180ºF, so there’s potential for massive heat loss to the surrounding air and soil (if your pipe is installed underground). Underground installation also raises the issue of ground water. Whatever pipe insulation you use, it’s got to remain free from

solar controller display shows key temp and operation info about solar heater operation

solar controller

collector temperature sensor wirecirculation pump wirepower supply wirewater tank temperature sensor wiredisplay wire

SOLAR TAX CREDITS

The US federal government is offering 30% tax cred-

its for qualifi ed solar water heating systems placed

into service no later than December 31, 2016. Systems

must be certifi ed by the Solar Rating and Certifi cation

Corporation (SRCC) to the OG-100 standard. Similar

federal tax credits are also offered for wind and pho-

tovoltaic systems. Your state may also have credits

that apply over and above federal help.

SMART & EFFICIENT PUMPSCirculator pumps are a necessary part of ev-ery hydronic heating system because all sys-tems use moving hot water to transfer heat. What’s not so similar is the different kinds of pumps involved in making that water move. Most simply

spin and move water, regardless of whether valves are open or water is allowed to move at all. It’s wasteful to have circulator pumps trying to dead-head water against closed valves, and that’s one reason smart pumps were invented. They use internal sensors to monitor the resis-tance to water fl ow, automatically adjusting pump out-put to match. The most sophisticated smart systems I’ve installed use Grundfos Alpha pumps. They include three speed settings, plus settings to keep fl ow rate constant or head pressure constant – whatever you want. The bot-tom line is quieter, more elegant operation, plus very low electricity consumption. In tests I’ve run, smart pumps move 2 to 3 gallons per minute of water, with a power consumption of only 25 to 30 watts. Conventional cir-culator pumps often consume 500% more electricity for the same amount of water fl ow.

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PREPPER PROJECTS

water saturation at those times of the year when things get soggy. Wet insulation is no insulation at all. Effective insulation and water resistance are the two main reasons we recommend manufactured pipe encased with a waterproof insulation system. Don’t skimp.

The most successful insulated water line installations I’ve done use an insulated pipe product called PEX-Flex. It’s made by a company called Logstor in Denmark. This is one of several Nordic countries that are at the leading edge of district heating, so they’re experienced at effi ciently moving heat underground. The outer covering of the pipe is continuous, very tough and completely waterproof. Inside you’ll fi nd two smaller pipes. The one inch diameter pipe size offers plenty of fl ow volume for the kind of water coming out of a solar water heater. One pipe delivers hot water to buildings from the solar collector, and the other brings cooler water back to the collector for reheating. The space between inner and outer pipes is fi lled with closed cell polyurethane foam insulation that’s resistant to water

OVERHEATING PROTECTION OPTIONSEvacuated tube solar collectors are powerful enough to boil the water or antifreeze solution inside them, and boiling is bad on two counts. First, boiling makes an-tifreeze more acidic over time, leading to corrosion of metal parts. Boiling also causes high internal pressures within a solar collector and stops the system from de-livering heat to your collection tank. Water circulator pumps can’t move vapourized liquid.

So what can you do to safely handle excess heat so it doesn’t result in boiling? Besides sizing your evacuated tube system to match your needs, it all comes down the functions of the solar controller. When a too-high collec-tor temperature is being approached, a thermometer sig-nals the controller to send hot water to a secondary insu-lated “over fl ow” tank or send the excess heat into the air. Got a runaway evacuated tube collector that’s running too hot? Simply shade the tubes with a blanket, tarp or light piece of plywood. No matter how hot the water is inside, the outside of the tubes remain cool enough to be safely covered by something touching them. If you go on vacation and won’t be using heat from your collector for a while, shade the tubes securely to avoid overheating troubles while you’re gone.

cooler water flow to solar collector

waterproof outer pipe

hot water flow from solar collector

closed cell foam insulation fills outer pipeand surrounds inner pipes

PHOTOVOLTAIC WATER HEATING?Photovoltaics (PV) is the name for silicon technology that converts sunlight directly into electricity. And until recently PV was used exclusively for just that – making electricity for use running things made to operate on it. But as the cost of photovoltaic panels declines, some people are beginning to use PV to simplify the solar water heating process. That would have been considered crazy a few years ago, but there are two reasons it’s happening now: dropping cost of PV panels, and rising sophistication of inverter technology.

Connect PV panels to a special inverter to convert DC power to variable AC power, then use this inverter to power the heating elements of an electric water heater or baseboard space heater. This is the PV water heating proposition in a nutshell. This method side-steps the need for pumps, pipes, heat exchang-ers and plumbing, and it could catch on because of simplicity. Probably will. According to Andy McKegney, a 35-year veteran of the solar heating industry, “This is the way solar heating is going to go.”

A handful of inverter technologies exist for using PV power to heat water, but according to our research here at The Prepper Project, something made by a company called CyboInverter is the best by a long shot. Maximum power output of each unit CyboInverter 1200H is 1200 watts, and it has leads for con-

necting four 300 watt photovoltaic panels to this single unit. Voltage output from the 1200H varies depending on how much sunlight is hitting the panels, maxing out at the 240 volts that electric heating elements are typically made to run on. Variable voltage and phase outputs makes no difference to electric heating elements. Two CyboInverter 1200H units can be connected together to provide 2400 watts of peak power, which is a reasonable amount for water heating. This arrangement can be connected to the bottom element of an electric water heater, with grid connections powering the top element. Another version of the CyboInverter, the 1200HH includes a switch that automatically diverts power away from a water heater when it reaches full temperature, directing power to a baseboard heater for space heating.

INSULATED HOT WATER PIPE SYSTEM

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PREPPER PROJECTS

absorption. The outer layer of pipe is continuous from the collector to the building, keeping water away from the foam just to make sure it doesn’t soak in. The whole arrangement is so effective that 180ºF water entering one end of the pipe loses only a degree or two of temperature after traveling 100 feet. You won’t need fancy insulated pipe if your collector is on your roof and just a few feet away from the hot water storage tank, but not all installations can be like this.

Moving hot water is the job of circulator pumps, and the technology available here is excellent and highly refi ned. Today’s circulator pumps can run silently for many years, using small amounts of electricity to move large amounts of water. Grundfos, Taco, Bell & Gossett, and

Apollo are all big names in the industry. At a minimum you’ll need a circulator pump to move hot water from the collector and back again. You may also need one or more circulator pumps to handle water fl ow in your house and buildings.

Regardless of your setup, there are two main things to remember about choosing and installing a circulator pump. First, circulator pumps must always be installed so the shaft of their motor is horizontal. This is the way pumps are designed to last the longest. It will shorten the life of a pump dramatically if you install it with the shaft oriented vertically. In other words, you want the cylinder shape of the motor oriented horizontally.

Second, variable speed pumps offer an advantage because you can dial in more or less water fl ow as needed. It’s not always easy to choose the right size of pump for your installation, and a variable speed model allows you to adjust water fl ow under actual use. It’s also often useful to be able to vary water fl ow depending on the season. Two very good general-purpose, variable-speed circulator pumps in my personal experience are the Grundfos 15-99FC and for larger applications the Grundfos 26-99FC.

Part 3: The Heat Exchanger SystemThe hot water (or antifreeze/water solution) coming into your home from the solar collector outside is part of a closed system in our design here. This means you can’t simply make use of the hot liquid directly. The hot water that moves to and from the collector is separate from the hot water that will come out of your tap or heat your home. You need to extract the heat from the collector water so you can use it to warm a fl oor or make a shower hot. Separating

the heat from the collection liquid is what a heat exchanger does. The best type for a solar system are fl at plate designs that have four ports. (Don’t confuse the use of the term “fl at plate” heat exchanger with

the completely different thing called “fl at plate” solar collector. The two are entirely different.)

One pair of ports on one side of the heat exchanger allows solar-heated water to pass through them – hot water supply coming in from the collector; and cooler water going back to the collector for reheating through the other.

The other side of the heat exchanger has another pair of ports – cold water going in from the household supply or infl oor heating return loop; and hot water going out from the exchanger heated for use in your home. The two streams of water from the collector and

EVACUATED TUBE COOKINGSince evacuat-ed tube collec-tors generate temperatures high enough to boil water, the potential exists to cook food in them, too. The only issue is tube diameter. Most evacuated tubes

are way too small to be practical to accept food or for cleaning afterwards. But large-diameter collector tubes do exist and they work well for cooking. The 4” diameter evacuated tube by Rand Solar is a case in point. Fill it with ingredients for soup, stews, meat and other meals, close the vented silicone stopper, then put the whole thing in the sun. You can put the food directly in the tube, or use mini pans that slip inside. The 3 13/16” inner diam-eter of the tube is large enough to hold useable amounts of food and to scrub clean later. Being made of glass, you do need to be careful to treat the tube gently. Cost is about $60 for one 25”-long tube.

cooler glycol solutionreturn from heat exchanger

hot glycol solution supply from collector

3” x 8” – 20 to 40 plateheat exchanger

water preheated by solar before entering water heater

cold watersupply to tank

open valve to by-pass heat exchanger

close valve todirect solarheat into tank

open valvesto flushand cleanheatexchange

open valves to allow cold to circulatethrough exchanger and get hot

HEAT EXCHANGER/WATER TANK CONNECTION

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PREPPER PROJECTS

household fl ow never mix, but heat is transferred from the collector supply to the household supply. You can have 50ºF water fl owing into a collector at one port, and that same water will come out 100ºF hotter after a fraction of a second in contact with the heat exchanger. There are limits to how much heat a fl at plate exchanger can handle, but the output from even a large residential solar water heater can be handled by one of the smallest heat exchangers. A 3” x 8” size with 20 or 30 plates will do the job.

Part 4: Heat Delivery and Control SystemsIt’s one thing to have solar-heated water coming into your house, but that’s not going to keep your house at a comfortable temperature without other gear. For this to happen you need two things: a way of distributing the heat around your house evenly, and a way of controlling the temperature of that distribution.

There are three options for delivering hot water heat to your home. Each has pros and cons:

INFLOOR HEATING SYSTEMS: very comfortable on the feet, but complicated and expensive to install. Infl oor heating systems can be put over and under existing wood fl oors, as well as embedded in concrete fl oors as they’re poured.

HOT WATER RADIATORS: simpler to install than infl oor systems and old cast iron radiators are especially beautiful and effi cient; can sometimes be troublesome to install hot water pipes. The best rads are antique ones reclaimed from old buildings.

HEATING COIL IN PLENUM OF FORCED AIR FURNACE: very simple to install and makes use of existing heating system; the fan of forced air systems creates a larger electrical load than similar hot water hydronic systems with circulator pumps.

Hot water hydronic heating of all kinds is gaining popularity across North America, and certainly not just for solar systems. Hot water heat delivers more comfort with less noise and airborne dust than forced-air systems, and people naturally like that. There’s one big problem with hydronic heating, though. Hot water systems controlled by simple thermostats have a tendency to over-shoot thermostat settings, making rooms too hot. By the time an ordinary thermostat or fl oor sensor registers that a room has risen to the set point, there’s still signifi cant thermal energy stored in the hot water in fl oor pipes or wall radiators, ready to move into the room and overheat it. The fl ip side of this is the problem of lag times. It can take longer for hydronic heating systems to bring rooms up to set point temperatures because it takes time for heat to move from the water to the room. Either way, the result is room temperatures that aren’t always right, but a unique control system solves both these problems perfectly

HEAT EXCHANGER MAINTENANCEEvery fl at plate heat ex-changer has many thin inter-nal fi ns (called “plates”) that water passes over, transfer-ring heat from the collector water to the water that runs through your heating or do-mestic hot water system. The water you put in on the collector side should be soft, with a low concentration of minerals and the addition of an anti-freeze/anti-corrosion supplement. The kind of ad-

ditive they sell for outdoor wood boilers works well. Since the collector side of the system is a closed loop, the low mineral content of the water means that no minerals will build up on the heat exchanger fi ns. Not necessarily so on the other side of the exchanger. If your household water has minerals in it (and most do), these minerals will build up as scale on the heat exchanger fi ns, slowly reducing the effec-tiveness of heat transfer. This is why it’s necessary to plumb the heat exchanger so it can be fl ushed with a mixture of vinegar and water. Webstone (www.webstonevalves.com; (800-255-9529) makes valves especially for this function and they work great. Called “The Isolator” these valves have both shut-off capabilities and an openable port for fl ush-ing. Flip the main valves OFF (you put one valve on each of the matching ports on the exchanger), open the fl ushing ports, then use an electric pump to force the vinegar and water solution through the exchanger until it runs clear. I use a Liberty Pumps model 331 for this work. Put a couple of gallons of a 50-50 water-and-vinegar solution in a 5 gallon pail, draw the solution from this pail and into the exchanger using the pump, then have the same solution fl ow back into the bucket after it leaves the heat exchanger. It usually takes 10 or 15 minutes of cycling like this to completely clean the internal fi ns of the exchanger. I have moderately hard water at my place (16 grains of hardness) and I descale my heat exchanger once a year. That’s plenty.

“It’s easy to take warmth for granted

when it’s always there. But do you really

want to rely on a system hanging by a

thread to keep you from freezing?”

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PREPPER PROJECTS

Four years ago I installed two hydronic heating systems in two buildings on my own property. One system used a regular wall thermostat with a fl oor sensor, and another used a smart control system by a company called Tekmar (www.tekmarcontrols.com; 250-545-7749). I’d heard good things about this company and I wanted to test the claims myself before recommending their system. I’ve monitored both systems closely and the difference in temperature stability has been dramatic. Room temperatures in the building with a conventional hydronic thermostat regularly vary 5ºF or 6ºF beyond the set point, while the Tekmar system always maintains room temperatures within less than 0.5ºC of the set point. In practice, the Tekmar system is smart enough to call for hot water fl ow even when room temperatures haven’t necessarily dropped to the set point. It learns the cooling rates of a given room at specifi c outdoor temperatures and anticipates heating needs ahead of time. The system often cuts off the fl ow of hot water before room temperature has reached the set point, knowing that temps will creep up and hit the set point just the same.

Part 5: Backup Heating SystemThe only regions where solar heating technology might provide all the space heating and water heating needs is in warm, sunny climates that don’t need that much heat in the fi rst place. The more you need heat in the climate where you live, the less likely solar is able to do the job on its own. So if you want consistent heat, most solar systems need to be partnered with some alternative heat source. This alternative may not have to contribute much, but it does need to be there.

From a prepper’s perspective there’s no substitute for having a supplemental system that includes a large supply of stored energy on site. This knocks grid electricity out of the running on two counts. Not only is grid power vulnerable to long term outages, but even short term power outages leave you with nothing. You simply can’t store it.

Propane is a reasonable backup option because many months of energy can be stored on site. Propane also dovetails well with evacuated tube solar collectors. A large, propane-fi red water heater is a perfect example. A solar collector can keep the water in a propane heater hot whenever the sun shines, with the propane thermostat set to kick in as the solar input declines due to the season or weather. The solar collector can be connected directly to a propane water heater like this, or to an insulated storage tank that heats the water in the heater indirectly.

A previous Prepper Project showed how an outdoor wood boiler is an ideal survival prep feature if you live anywhere near forests, and outdoor boilers work very well with a solar water heater – either alone or as part of a solar/wood/propane system three-way hybrid. Either way, stockpiling propane in large tanks on your property is a very wise prepper move because propane can be used for so many things: lighting, heating and a dozen other things that use electricity generated with that propane. It might not be renewable itself, but if you’re more interested in being prepared than being green, then a couple of big torpedo tanks of propane are something you should look at.

The sun is one of only a handful of energy sources that keeps on delivering, regardless of what happens in the wider world. That’s why solar technology has earned a place with serious preppers across the country. Equip your self with the right kind of gear, get it working now while things are still sane, then the heat you harvest may well be the new kind of gold.

“Solar is the only energy source

that’s automatically delivered to

your home no matter what’s happening

in the rest of the world.”

OLDER CAN BE BETTERCast iron radiators were used for so long, and in so many buildings across North Amer-ica that there are literally mil-lions of radiators in service today. Renovations, demo-litions and ignorance-based “upgrades” means that thou-sands of these beautiful radi-

ators head for the scrap heap each year, even though most are as reliable and effective as the day they came out of the foundry. The work of intercepting these paint-encrusted relics on their way to the smelting furnace is a job taken on by a handful of radiator restoration companies. Google “cast iron rads” and you’ll fi nd them, though you do need to understand something.

It’s rare to fi nd cast iron hot water radiators that aren’t coated in ugly paint, and removing it offers two advantages. While old, crusty coatings hide beauty, they also hold back heat. Bare or minimally-coated iron rads transfer about 10% more heat to the room, all else being equal. This is why sandblasting is the industry standard for stripping iron rads, though it’s not the best option. While sand blasting does remove paint, it also dulls the fl oral and decorative details that make ornate rads so beautiful. The best rads are refurbished with a gentler system of hot water stripping that respects original surface designs and textures.

“Solar heating is a great foundation for

survival prep, but it should be combined

with other independent technologies,

too. Several strands make a cord strong.”

11

PREPPER PROJECTS

Steve Maxwell and his family live on a 90 acre rural islandhomestead in Canada. For nearly 30 years he’s taught people how to be more skilled, self-reliant and capable. Connect with Steve online at BaileyLineRoad.com.

“Love thy neighbor means more than

just smiling and being nice. It also means

preparing yourself to help others when

the world they rely on lets them down.”

SOLAR HEATING – A REAL-WORLD CASE STUDY

Reiner Hoyer lives at

about 440 latitude,

in a place where it

regularly gets down

to -300F. So when

he tells you that

it costs him $20 a

month to heat his

home during the

coldest times of the

year, you have to sit

up and take notice.

Hoyer’s got 30+

years experience as

a contractor, and

building his own

house was his chance to put all the latest and greatest ener-

gy effi cient building features into action. Besides super-high

levels of foam insulation, the nearly-zero heating bills he has

come thanks to the solar system he uses to harvest heat.

The Hoyer home has been visited by an international del-

egation of energy effi ciency enthusiasts and is certainly

among the most noteworthy buildings of its kind in North

America. Building code requirements forced Hoyer to install

an air-to-air heat pump as a back-up heat source, but it’s

mostly just for show.

The small amount

of energy required

for space heating

beyond what’s pro-

duced internally by

cooking, lighting

and warm bodies is

usually supplied by

a rooftop evacuated

tube solar collector.

It provides domestic hot water, too. One sunny day when it

was -100C outdoors, for instance, the vacuum tube system

heated Hoyer’s 150 gallon insulated water storage tank all

the way up to 600C. Space heating is delivered through a

hydronic infl oor heating system that also extends out onto

the concrete front porch for melting ice and snow.

“Preparation is patriotism.

If you love your country, you’ll do all

you can to make sure you can keep it

working when things go wrong.”

HANDS-ON INFLOOR HEATINGRadiant hydronic infl oor systems are the most technically complicated way to get hot water heating into your home or shop, but it’s also quiet, clean and especially comfortable. You’ll be able to stay comfortable at lower room temperatures when your feet are warm. I’m not a professional hydronic heating contractor, but I installed the system you see here myself. It looks complicated but is simpler when you understand what each area does.

The U-shaped network of 1/2” pipes fans out to different areas of the fl oor above. Each pipe fi ts into an aluminum track that conducts heat to the underside of the wooden subfl oor. All these pipes start at the manifolds – the two brass bars that supply hot water to the pipes and collect cooler water for reheating. The white caps on the top of the uppermost manifold are electric valves that open and close depending on which pipes need hot water. The red cylinder just left of centre is a fi lter that keeps the heating water clean of sediment. The items to the left of the fi lter are circulator pumps.