Solar Heating Rev 3.0

Here comes some serious solar heat

I lived with solar heat from the Rev 2.0 system for two heating seasons, 2001 and 2002, and was not getting very warm on cold winter days. I experimented with varying the airflow and when the blower turns on and off. What I  found is that the system was working as well as could be expected. The maximum amount of heat it could supply was being harvested and delivered into the house. What is needed here is a larger heat collector.

Rev 2.0 Solar Heat Collector

[ photo of Rev 2.0 used for 2001 and 2002 heating seasons ]

Rev 3.0 Solar Heat Collector

[ photo of Rev 3.0 for 2003 and beyond ]

This is the larger heat collector. You can see that I adopted the design of Rev 2.0 system by simply extending the down spouts from 10 feet to 20 feet in length. Effectively doubling the size of the solar collector  should increase the total amount of heat delivered into the house. I hope I'll be warmer on cold winter days. We'll see... The swamp cooler is also attached to the house at the same time, so no more rebuilding things when seasons change. There is a removable insulation partition inside the swamp cooler to close it off completely during the winter heating season.

A less obvious thing you can't see in the photos above is where the cold house air enters the solar heat collector on the left end. I had to cut a new hole into the house to make that connection. I thought about this  for a long time. How best to do it. My final decision was to cut an opening at the end of the wall between floor joists. The result would be an opening 16 inches by 8 inches, more than was available for the Rev 2.0 crawl space vent design. What I didn't feel comfortable about was removing a section of the base plate at the end of the floor joists. Several years later there are no signs of a problem. I guess it is OK...

[ photo of mid-section down spout support ]

Two 10 foot down spouts joined end to end is a long span. All that weight will make the center joint sag and pull apart. Support is needed in the middle to hold the down spouts level for the whole 20 foot span. In the center of the solar heat collector is a steel frame with holes drilled in it where I attached 3 inch long 1/4 inch bolts. The bolts hold the down spouts level with no special attachment necessary because gravity holds them  resting against the steel frame and the bolt.

[ photo of down spout end attachment ]

On either end of the solar heater the down spouts are secured with a steel plate. Rectangle holes are cut into the plate which holds the spacing between each down spout. In this photo you can see caulking is used to seal the heat collector box from the heated air flow. The heat collector box is sealed air tight while cold house air is blown into the ends of the down spouts shown here. Heated air emerges from the other end of the down spout's 20 foot span.

Some things I learned from the Rev 2.0 system

[ photo of access door for furnace air filter ]

• Furnace air filter

Here you can see a little frame on the end of the solar heat collector in the lower left corner. It's an access door into the cold house air inlet. Behind the door is a standard size furnace air filter 14 by 20 inches. Previous designs didn't have an air filter. Inspection of the system at the end of the heating season revealed  evidence of dust collecting in the down spouts. Well, the first time I changed the filter after a heating season it was obvious how necessary an air filter is. Yuk! Really necessary.

[ photo of cold house air entrance end ]

• Access to internal workings

You can see two aluminum straps with latches across the front of the box. These are easily removed to allow the cover to be lifted off to get inside for servicing. Rev 2.0 showed me how important it is to access the internal workings of the system. Rev 2.0 was held together with lots of wood screws...

[ photo of aluminum strap with latch ]

• Sun and weather destroy things

The removable end covers have a layer of galvanized steel sheet metal tightly fitted. I carefully cut the sheet metal and formed it around the wood. When the fit was just right I soldered all the seams to completely shield it from the weather. Sun, rain and snow destroyed the Rev 2.0 covers in just two seasons! The value of learning from the previous experiment is priceless.

[ photo of finished hot air plenum attached to swamp cooler ]

• Switch between Winter heating and Summer cooling

Rebuilding things isn't fun when the seasons change from heating to cooling. The solution was to modify the swamp cooler steel air plenum by cutting one side off. This opened a passage way for warm air to pass in front of the swamp cooler and into the house.

[ photo of housing around swamp cooler plenum ]

After modifying the swamp cooler plenum I built an insulated housing around the whole thing, seen above. Insulation is necessary for the Winter heating season to keep the heated air from being lost. The top of this section is covered with galvanized sheet steel soldered together and formed around the enclosure for a tight fit. Sun and water on this area will destroy wood within a couple years. Yes, that's experience talking... It was originally just painted wood, and it didn't last two years!

How well does it work?

Very well actually! There are still cold, cloudy Winter days when no heat is collected. When the sun does shine, however, it really warms the house. I use the term "warms" here as a "relative" measurement. What's that mean? Well, if the house is 45 F degrees in the morning, a sunny day with freezing temperatures outside will heat the house to around 60 F or 65 F degrees. So 60 F degrees is "warmer" than 45 F degrees, and it feels pretty nice too, when you remember how cold it was when the day started. And yes, if it remains cloudy all day the house remains at 45 F degrees. On those kind of days I'll use the wood heater or kerosene heater to add a little heat.

During Spring and Fall seasons when the outdoor temperature is generally moderate around 35 F degrees to 50 F degrees, the solar heater warms the house to around 70 F or 75 F degrees. Sweet! So, yes, the solar heat collector is working very well for me.

Ongoing improvements

This Rev 3.0 system has been working well for me since I installed it in March 2003. Between then and December 2005 I used the blue squirrel cage blower described in my Rev 2.0 post. During this time I was exploring the possibility of powering the solar heat collector with solar electricity. I found that it is possible and probably a good idea to make it happen. On my electric bill I could see the affect of using the squirrel cage blower, it was a little higher during that time.

In March 2004 I installed solar electric panels in my back yard. I had been working on a design for a solar heat fan controller system during this time. It would measure the temperature of the indoor air and measure the temperature of the solar heat collector air. When the solar heat collector air is warmer than the indoor air it would turn on the fans to move the heated air into the house. This way it should get the most heat into the house and use the least amount of power to do it.

[ photo of solar heat collector fan controller circuit board ]

[ photo of fan controller front panel ]

This is the Fan Controller board I designed and built. It uses a Microchip PIC 16F628 processor chip. The job of this circuit is to open and close a duct work damper, turn the fans on and off with three speed settings. The duct work damper closes off the air path through the solar heat collector to prevent cold air from entering the house, back draft. This Fan Controller board communicates with a wall thermostat via RS485 serial network link.

[ photo of wall thermostat Solar Controller ]

The Solar Controller shown here is also my design using a Microchip 16F876 processor chip. It's job is to make all the decisions: when to turn the fans on and off, set fan speed, measure indoor air temperature, and get solar heat collector air temperature from yet another Microchip controller.

Fan speed is slow when the difference between inside air temperature and the solar heat collector air temperature is about 6 F degrees. Medium speed at 12 F degrees and High speed when the temperature difference is above 18 F degrees. This controller is also connected to another via RS485 serial network which monitors the air temperature inside the solar heat collector.

[ photo of solar heat collector air temperature monitor ]

The Solar Temperature Monitor is shown here. Yes, I know, it's just sitting on a cabinet inside the house next to the warm air inlet. And it's just a modified "prototype" board from Micro Engineering Labs. The wires connect it to the RS485 serial network, 12 volt power, and the temperature sensor located inside the solar heat collector. I am planning on building a board specific to this purpose, enclosing it inside a metal box but just haven't got around to doing it. The saying, "If it ain't broke, don't fix it," comes to mind here. I've just been putting it off because "other" things are just more important. And so here it sits, operating perfectly for 8 years now!

Let's take a look inside the finished system...

Starting at the cold house air entrance we see there's a lot going on here. First a front view of the box with the cover removed.

[ photo of cold house air entrance ]

The front cover door is leaning against the house at the left. Inside the box on the lower half you can see 2 round black circles: these are the new 12 volt DC fans which replace the 120 VAC squirrel cage blower previously used in this location. Above those is a gray box with several flexible conduit cables attached. This is where the Solar Fan Controller is located.

[ photo of Solar Fan Controller installed and operating ]

LED indicators on the front panel show the current system status: NET on the left blink when transmit and receive network packets are being exchanged, FAN in the center show OFF (bottom) LOW, MED, HI (top), DAMP on the right shows the damper position OPEN or CLOSED. Fuses on the left are 5 volt for the logic board and 12 volt for the fans and damper.

[ photo inside cold house air passage way ]

Inside the access door on the left side of the box is where the furnace air filter is located. Both fans pull cold house air through the duct work behind the filter and force it into the solar heat collector's down spouts.

[ photo of heated air output end box ]

Heated air emerges at this end of the down spouts into this collector box. Notice the much thicker insulation on this end. That helps retain as much heat as possible before it enters the house. You can see some other things going on inside here too.

[ photo of baffle and wall thermostat ]

The diagonal piece of foam insulation is a baffle to prevent excessive air flow around the wall thermostat you can see at the top. The wall thermostat is used here as a "fail-safe" device. If the micro controllers should ever fail to run the fans when the sun is heating the down spouts, this thermostat will click-ON forcing the fans ON at full speed. That should prevent a melt-down of the solar heat collector by keeping air circulating.

Again, yes, this is experience speaking from a previous "event" that did some damage. Foam insulation inside the down spout box partially melted from the heat! Ouch! The original software program I wrote for the wall thermostat in the hallway was at fault. It didn't convert temperature above 120 F degrees correctly, and just shut off the fans. Oops... Programming is now fixed, and this fail safe wall thermostat is now a permanent part of the system. The program and the fail-safe device have both been tested. They both passed. Now I feel better about the safe operation of the system. Lesson learned.

[ photo close up of wall thermostat ]

I am using the "air conditioner" contacts in the wall thermostat to close the fan circuit when the temperature here goes above 80 F degrees. You can see the dial setting red pointer on top. The bottom red pointer is ambient temperature and as you see it is off-the-scale above 100 F degrees. It's a good heating day!

[ photo of solar heat collector temperature sensor clip ]

This alligator clip holds the temperature sensor a short distance inside one of the down spouts. When the temperature of this sensor is 6 F degrees above room temperature inside the house, the damper opens and fans turn ON.

[ photo of warm air entrance into the house ]

Directly below the diagonal foam baffle is the opening where the warmed air passes into the house. Notice the liberal use of very thick foam insulation around the area. This is to keep as much heat in the air as possible.

Why such expensive fans?

[ photo close up of one of the 12 volt DC fans ]

I did a great deal of searching to find the fans I chose to use here. Two very important factors had to be met for this purpose:

1. Low power consumption.
2. High enough CFM (Cubic Feet per Minute) air flow.

These are two opposing features... You can have High air flow but you will have High power consumption. On the other hand you can have Low power consumption but you will have Low air flow. Papst brand 8 inch 12 volt DC fans move 235 CFM with only 1 amp draw from 12 volts DC. ONE AMP! Sweet. The closest competitor had the same air flow but uses 2.2 amps at 12 volts DC. Of course this efficiency comes at a premium price, $100 per fan. The 2.2 amp competitor could be had for $25 each.

You must ask yourself this question, "Do I spend the money on high priced fans and build a smaller solar electric system, or do I build a large solar electric system and buy cheap fans?" Let's go through some numbers and see what it looks like.

• $200 for two expensive fans
• ...OR...
• $2000 for a couple more solar panels
• ...PLUS...
• $1800 for batteries to handle the load of the cheap fans, total $2800

It looks pretty clear to me that the expensive fans are a better choice. Things work a little differently when you want to use solar energy at your home instead of grid electricity.

Solar energy requires a new way of thinking...

This is the reality of solar energy with current technology. Solar energy works and is worth the effort however, the most important thing you will learn is conservation. You must use less than what you were while living on the grid. It's so easy to get comfortable connected to a seemingly "limitless supply" of electricity and natural gas. Making your own in your back yard is a limited supply. Your heat and electricity supply are now governed by the weather and your daily use of it. Your neighbors trees shading your solar panels and solar heat collector factor into this as well. You might have to wait for the next sunny day before you can do that load of laundry or vacuum the floors.

Some of these things may not be appealing to you. I've struggled with all of them myself. They'll change your lifestyle, they have changed mine. Daily routines aren't so routine any more. When your home's power and heating is dependent on the weather, you will become acutely aware of what's going on outside. With the few years of experience living like this, it isn't so bad. Freedom from being tied to a utility for electricity or heat is a powerful feeling. I like the independence. I like being in control. Yes, this is worth the effort and lifestyle changes.

Natural gas use since 2001

The natural gas bill "event" February 2001 changed my life, for the better I think. My days and nights at home in Winter may be cooler and less comfortable than before the event but those aren't the only side effects. Here are two other side effects:

[ photo of recent natural gas bill ]

As you can see I'm no longer into "three digits" on my gas bill, saving some money in the process. The little graph on the gas bill kinda looks like the chart below. That's because natural gas only heats the hot water in my house. The dollar amount you see in the photo above is what I have been paying each month, every month since the "event" in 2001. Yes, over ten years now, less than $20 per month! Sweet!

[ chart showing annual usage ]

Clearly something is different starting in 2002. What you are looking at is hot water heater only from 2002 onward to today. The fiscal year 2013 is currently in progress, that's why it looks smaller that 2012. I think these two "side effects" of the lifestyle change are good ones.

Modifications to the swamp cooler

Having a large 1/3 hp AC electric motor pulling about 700 watts takes a toll on my solar electric system. There is also an AC water pump that sits in the bottom tray of the swamp cooler takes an additional 130 watts to operate. 830 watts. Running this on a 12 volt to 120 volt AC power inverter which is only 80% efficient means total power from the batteries is 830 x 1.2 = 996 watts total. Ouch!

To remedy this situation I converted it over to use 12 volt fans and a 12 volt bilge pump. 12 volt fans pull about 30 watts directly from the batteries. 12 volt bilge pump pulls about 24 watts directly from the batteries. The new total is only 54 watts, and they don't use the 12 volt to 120 volt AC power inverter. Now that's a huge improvement and I'm saving some power for other things in my home.

[ photo of original 1/3 hp driven blower ]

The original squirrel cage blower, shown here removed from the swamp cooler, would move a large volume of air very quickly. With that much air moving it would cool the house down quickly. I would then switch the blower to a slower speed to keep from freezing myself in the middle of Summer. Anyway, it's big and uses a lot of power to run. More power than I wanted to use from the solar electric system powering my house.

[ photo of swamp cooler with blower removed ]

Lots of empty space inside now! The little red and white thing sitting on the bottom is the bilge pump.

[ photo of 12 volt fan array inside swamp cooler ]

The new 12 volt DC fans, 6 of them installed onto a board for easy removal. Each fan draws about 0.4 amp for a total of about 2.4 amps, 30 watts. These fans don't move the large volume of air that the original squirrel cage blower. Give it a little more time and the cooling effect through the house is the same. Are these fans noisy? No. The sound is a higher pitch whining but not loud at all. These were designed to be quiet. You have to strain to hear them running from the other end of the house. Nice cool breeze and using about about 950 watts less than before. That's cool!

Photo Gallery

Solar heat collector

Gregg Scholfield    5-3-2013

Solar Heating Rev 2.0

Improving on solar heating

With only two down spouts inside a marginally engineered enclosure, it is unable to supply any useful amount of heating. It did, however, prove the concept and lay the foundation for improvements.

First step: Make the heat "entrance" into the house...better

There is an opening through the wall of the house where the swamp cooler attaches for summer time cooling. For this experiment I just removed the cooler and set it aside. Cut some foam insulation board to fit the opening, then cut a round hole in it to attach the 8 inch insulated duct hose. Here is what that looks like...

[ photo of hot air entrance into house ]

This arrangement worked OK for the experiment, but I needed something better so both heating and cooling units could be attached at the same time. When the seasons change I wouldn't have to rebuild anything to switch to the other unit. I also needed a way to put a higher volume of warm air into the house. Here is the improved entrance...

[ photo of improved hot air entrance ]

The new warm air entrance plenum is built using 1/2 inch plywood and securely attached to the house with wood screws. Not a perfect solution to be sure, but the experiment isn't quite over just yet. You can see the provision for a second 8 inch insulated duct hose to be attached above the original. I'm already planning ahead for the next revision which may actually add some useful heat into the house.

I lived with this original system from October to mid-December 2001 to get some experience during the cold time of the year. Now it's time to make improvements to get some real home heating working.

Next step: Design a better solar heat collector

I did a lot of thinking about how to build a bigger solar heat collector. One that would adequately insulate itself from the cold temperatures while collecting the maximum amount of heat for the house.

New design parameters:

1. A light weight wooden box. Easy for one person to handle by himself.
2. Angle the front face to the Winter Solstice Sun declination at solar noon. That's a fancy way of saying on December 20 (solstice) at 12:00 pm standard time (solar noon) the face of the box will point directly at the sun. This is the setting for maximum heat gain during Winter months.
3. Foil covered foam insulation glued to the inside. The foil would reflect the suns rays onto the back of the down spouts for added efficiency.
4. A single layer of glass to close off the front facing the sun. Dual pane glass would insulate the box better but would also reflect much of the infrared radiation we're trying to capture.
5. Down spouts painted flat black. Absorb maximum infrared solar radiation.
6. The box housing the down spouts is air tight. We need to keep drafts out to retain as much collected heat as possible for the house.

Here is the result of that line of thinking. It's December 27, 2001, not even a year after the event with the natural gas company bill. Being cold isn't fun, so I am determined to get some heat gain right away.

[ photo of Rev 2.0 solar heat collector ]

There are 8 down spouts inside and two 8 inch insulated flexible duct hoses connecting it to the warm air entrance box. It's not quite finished yet because you can see wood blocks under the ends and the middle holding it up, and there isn't any caulking on the glass panes covering the front yet.

[ photo of Rev 2.0 from angle ]

Looking close at the left end you can see the improvement to the cold house air inlet into the solar heater. I built a wooden plenum to use the full opening on the house for improved air flow and added 1/2 inch foam insulation to the inside. Even though it's cold air from inside the house it's still warmer than outside air and we want to keep it that way.

[ photo of warm air duct hoses ]

Having two 8 inch insulated duct hoses greatly increased the warm air flow into the house.

[ photo of finished solar heat collector ]

The wood blocks supporting each end and the middle are gone now that the ends are attached to the house with wood screws. To prevent rain and snow from entering the box, white caulking can be seen between the panes of glass. Caulk is used around the perimeter of the glass as well. Now it's ready to do some serious work collecting heat for the house.

Where is the sun?

[ photo showing the angle of the face of the box ]

My house is on the 39th parallel. The sun's angle at the Winter Solstice is lower on the horizon by about 25 degrees according to the astronomy information I found about the suns incident angle. So 39 degrees minus 25 degrees is about 14 degrees. The face of the box is at 16 degrees from vertical or 64 degrees from horizontal to capture the most heat from the sun during the winter months.

These measurements can be confusing when looking at a protractor sitting on the plywood with pencil in hand. Using the earth ground as zero degrees, and point straight up into the sky as 90 degrees it's a little easier for terrestrial beings to grasp. So the slope on the face of the solar heat collector is at 64 degrees.

I measured the sun's position myself over the course of a year just to confirm the numbers. Here's what I got:

Sun is 65 degrees above the Southern horizon in Summer solstice (June 20).
Sun is 15 degrees above the Southern horizon in Winter solstice (December 20).

I measured these with care to find the sun's real position at each solstice. Yes, it took over a year to get these measurements. Actually several years because I re-checked my findings a few times to make sure they are accurate. You don't need to be this accurate to build a solar heat collector, I just needed to satisfy my curiosity by doing these measurements.

In the spring and fall the sun's angle will be higher resulting in less efficient heat capture during those times but that's OK. Outside temperatures will be warmer so we will be needing less heat anyway. And during summer months eaves on the house will partially shade the box from the sun when we don't want heat at all.

We need to move more air through the solar collector

The little duct booster fan won't do with the new larger solar heat collector, so a new blower is needed. I settled on a squirrel cage blower that is housed in an enclosure that can be put in-line, which means it can be inserted into existing duct work under the house.

[ photo of blower at output end ]

This is the end where air exits the blower. The opening is 8 inches diameter to attach to an 8 inch duct.

[ photo of blower intake end ]

Air enters the blower on this end. The black thing in the middle is the motor. You can see a few of the squirrel cage fan blades in the bottom of the opening. This end is also 8 inches diameter for attaching to 8 an inch duct.

[ photo of squirrel cage blower ]

Since the unit can attach directly to 8 inch duct work, this arrangement will work very well. All I have to do is open the connection between two sections of existing duct and insert this between them. I may have to adjust the length of the existing duct work to allow for the added length of the blower.

That's the plan anyway, but for now I just have it sitting on a rolled up bath towel curled around the floor register in the master bedroom. Pointing down so it will pull cold air out of the room and push it down into the floor register. All other registers in the house are shut off or plugged to prevent air from escaping back into the house instead of going into the solar heat collector.

We're moving too much air through the solar heat collector...

This arrangement worked very well. I was getting lots of warm air flow entering the house. But there is a new problem, the blower was moving too much air. It was cooling the solar heat collector to the point where cool air is entering the house. OK, I need a method of controlling the amount of air flow.

It turns out the company that sells this blower also has a speed controller made just for it. Great! So I got  one and wired it into the connection. Now the blower motor can be turned way down to just barely moving any air and all the way to full speed. That's what the system needed and it works very well.

[ photo of blower speed controller ]

Black and white wires connect between the AC line and the blower, the extra wires twisted together is a  modification I was going to add to the control. I wanted to control the speed of the blower by the temperature of the air inside the solar heat collector. It was never completed because the next big revision to  this system eliminated the need for this control. That's part of being an experimenter. Sometimes you move to the next level before completing the previous one.

Automated control for daily operation

The solar heat collector is slowly evolving into a real heating system. A system like this needs to turn on and off automatically. It needs to turn on when the sun comes up in the morning, and then turn off as the sun sets in the evening. Keeping things simple I'll just attach a timer to the blower's power connection. That way it will turn on and off at the times I've set on the timer. Great!

[ photo of automatic timer ]

Now the blower turns on in the morning after sunrise, runs all day and shuts off at sunset. The times for these events were determined on a weekend when I was home so I could be sure to get the most heating out of the day, and to keep from circulating cold air when the sun wasn't up. Controlling the blower like this isn't the best way, I know that, but it works. And yes, this is still an on-going experiment. Improvements to the system come one-step-at-a-time, and right now this is a minor one that I can take care of later.

How well is the solar heater warming the house?

It does pretty well. In the Spring and Fall seasons when I get home from work the house is usually 60 F to 65 F degrees. Not bad. On cloudy days there is less sun heating the collector so it doesn't do as well. The house may start out at 55 F in the morning and only get to 58 F when I arrive home in the afternoon.

Winter time heating can be even less when the daytime has clouds blocking the sun. The worst case is when there is no solar heating all day long. That's when the wood heater and kerosene heaters get put to use. I have gotten used to wearing warm clothes at home in the winter. It can get pretty cold inside the house mid-Winter during the week when there isn't a lot of time to heat the place up with the wood heater. I'll admit to waking up one Winter's morning to an indoor temperature of 38 F degrees. Yes, I know that's the "normal" temperature inside a good working refrigerator! This is my incentive to keep working on the problem.

Motivation moves progress forward

Look, I am motivated to find a solution to the high cost of natural gas heating. If I was sitting around a nice toasty warm house contemplating a solution to this problem, I might just click the remote to the next TV station and just sit there and think about it. Not much progress would be made that way. On the other hand, living inside a refrigerator occasionally will keep that motivation alive. Every day that I am cold to the point of being uncomfortable you can know that I am actively working on the next step to attaining my goal. This is what I call incentive. At 38 F degrees that's a lot of incentive.

Summer no-heat arrangement

[ photo of solar heat collector in Summer ]

During the seasons where solar heating isn't needed the solar collector is put into stand-by while the swamp cooler is in use for cooling. In this photo, taken 1-9-2003, the solar heat collector isn't even connected to the house for heating. What's up with that? I am working on the next improvement and haven't got it installed yet.

If you look closely at the picture at the lower left corner of the house you'll see a little white rectangle just above the concrete walkway. That is part of the next step in the design of the solar heat collector. And if you look up at the eve above the solar heater you can see a little black rectangle. That is the first step in solar electricity for me. More on that later.

The next step in solar heating

More heat! Please, more heat! Solar heat collection using rain gutter down spouts appears to be a workable solution from my experience with the systems I've tested so far. But this isn't enough yet. I need a bigger solar collector to get more BTU's into the house. That's where we're going next.

Gregg Scholfield   4-13-2013

How I got started with solar

I was pushed over the line by a large Natural Gas bill...

I have always been aware of how much energy is used in my home. My house is connected to utilities just like everyone else: Water, Electric, Gas, and a septic tank.

As the bills arrive each month I look for trends up or down to see how it varies. Like any one else there are times when the bills are high, an extreme cold winter or a very hot summer. Extra heating and cooling will add to the cost of electricity and gas. Over time you will have a sense of what to expect as you use energy. That knowledge allows you to spot something that doesn't fall within your expectations.

After 20 years of watching the numbers, it all became pretty routine, until...

Fast forward to February 2001 when it all came tumbling down, or skyrocketing would be a better word to describe the event.

First, let me show you a typical gas bill for winter months.

[ photo of typical winter heating natural gas bill ]

$65.90 you see here is right inside the average for this time of year. It might vary between $50.00 and $70.00 depending on how cold it was.

January 2001's bill should have triggered a flag telling me things are changing, but it didn't quite register yet.

[ photo of bill just before the big one ]

And now the one that blew the top off everything.

[ photo of the big one ]

I have NEVER gone into three digit territory with natural gas use EVER, but here we are! This is the RED FLAG that started me looking at everything. Past bills. Gas meter numbers. Looking for leaks. You name it, I checked it out.

What I finally found is in the photo above, the gas company raised the price. Not just an incremental change like you would expect with most consumer products and services. This was monumental. A $60.00 gas bill going to almost $120.00 is DOUBLE territory. That got my attention, and got me interested in solar!

From that day the thermostat on the wall kept going lower every day until I finally turned it off completely. Permanently.

I want freedom from this unstable source of energy.

That's when SOLAR ENERGY came into my life

I did a great deal of thinking about how to cut ties with the natural gas company and still heat my home during the cold winter months. Everyone has observed the effect of sun shining through the windows and onto the floor, the wall, table and chairs, it makes all of these things warm. I wondered if there was a way to purposely capture this "free" heat from the sun and distribute it throughout the house.

Research on this subject revealed something called a flat plate solar collector, used for heating air forced through it. The design looked simple enough. An insulated box with a glass window on the side facing the sun. A flat metal plate inside the box with an air space on both sides. An insulated flexible hose for cold air inlet and another hose for warm air outlet. A fan or blower to move air across one side of the flat plate.

That description made me recall a recent experience I had while installing rain gutters and down spouts on my house the previous fall. All the gutter materials are made out of galvanized steel. Some of the down spouts were leaning up against the house in preparation to be installed. It was a sunny day and when I went to pick one of them up to install it I nearly burned my hands on it.

Remembering this little bit of information led me to consider a design using down spouts instead of the harder to build flat plate system. The design seemed a little easier than dealing with a huge flat metal plate that would have to be supported in the middle somehow to keep it from bending. The idea of using rigid down spouts made good sense. They are hollow tubes which makes them rigid like a pipe, but thin walled so they are light weight too. I could run them from one end of the box to the other without having to design some kind of support structure in the middle. OK, it's time to do an experiment to see if it will work.

Solar Heating first attempt (the experiment)

I started small with just two 10 foot long down spouts in a very quickly constructed box. The "box" is a concrete form tube about 12 inches in diameter that I cut in half the long way. I didn't even put glass over the front of the box, just some translucent plastic tarp material, and insulated the inside of the concrete form tube with foil covered bubble wrap stuff. Yeah, duct tape everything together. This is just an experiment to see if I can capture any heat at all. Here's what it looks like.

[ photo of solar warm air heat collector ]

It sits on the walkway on the South facing side of the house. An insulated flexible duct hose connects the cold air inlet and warm air outlet of the solar heater to the house. The white square on the right is where the warm air enters the house. The swamp cooler is normally attached here but I removed it for this experiment.  The left end is where one of the crawl space vents is located. I removed the vent grill and stuffed the hose through the opening into the house. This is where the cold house air comes into the solar heater to be warmed up. I spliced the cold air hose into the furnace duct system to pull cold air from all of the floor registers in each room of the house. Yeah, there's a reversal here. Instead of warm air blowing out of the floor registers, there's cold air being pulled into all of them.

[ photo of entrance point of cold air from house ]

The purpose of the wooden box at the ends is to convert the single 8 inch diameter insulated duct hose to attach the ends of the rain gutter down spouts. The foam insulation seen here is also used inside the box to reduce heat loss to the outside cold temperatures.

[ photo of down spouts inside the "insulated box" ]

Pretty crude construction here with duct tape, plastic wrap, foil covered bubble pack insulation. Let's not forget this is just an experiment. We want to find out if this will work at all.

[ photo of duct boost fan blower ]

[ photo of inside duct boost fan blower ]

This little duct booster fan doesn't move much air. With all the bends in the airflow path, air movement isn't very brisk. Nevertheless it did manage to move some air through the system. I could feel warm air entering the house at the end of the insulated duct hose. The temperature at this point measured about 8 deg F warmer than the ambient temperature inside the house. Not bad!

So, does it work? YES, it does! And no, this thing didn't heat the house to a toasty 72 degrees, but it did heat the air circulating through the solar heater with a small duct "booster" fan. It wasn't very hot, but warm air is entering the house from sun shining on the down spouts outside. Amazing. Free warm air without having to buy expensive natural gas. The important thing here is that it proves the concept works.

The price of natural gas during the 10 year period following the 2001 "event"

[ Chart 1 ]

The chart above shows the HIGH and LOW price homeowners pay for one therm of natural gas during that year. In the event year, 2001, the low price was about $0.60 and high price was $1.00. That price jump is what started my solar energy quest.

Data to create this chart came from gas bills I receive in the mail from the gas company.

This should be a WAKE UP CALL for anyone using natural gas

Look what happened in 2007... the low $1.50 and high $2.48. Wow! That's a huge jump from the $0.60 I used to pay for gas. It looks like pricing stability for natural gas ended in the year 2000.

The next step in solar heating

Take the concept of solar heat collector and build one capable of supplying usable heating for the home. I do exactly that in the next post. It's bigger. Better design. And may actually keep the neighbors from complaining about the ugly stuff in my back yard. Well, maybe...

Gregg Scholfield   3-26-2013