The Bill Comes Due

You know the feeling don't you?  You open up, say, the credit card bill at month's end and you think, all those little numbers cannot possibly add up to that BIG number at the bottom of the bill.  Unfortunately, all those little numbers do add up.  And so it is true with my solar hot water project.

Jumping to the bottom, the number is $12,000, give or take a little depending on what you include.  And, yes, that is a lot.  But I was not trying to do a budget job, and mistakes along the way cost mucho dinaro.  Still, assuming the federal government pays for 30% that leaves only $8400 for me to make up with oil savings and still seems possible within a few years.  More feedback on that later.

There are a handful of big ticket items and about one hundred smaller purchases.  To begin, let's talk about the larger items or main components which total $6353.12.

System Vendor Date Description Price 1 Solar Panels EcoDirect.com 08/04/11 Solar Panels $2,829.85 2 Tank Houseneeds 09/25/11 Hot water tank $1,825.08 3 Hydronics Houseneeds 08/09/11 Pump Station, fittings $557.83 4 Hydronics Portland Group 04/12/11 NA26711 Caleffi pump $363.63 5 Controller House Needs 03/29/11 iSolar Plus Controller $333.75 6 Hydronics SunVolt Energy 11/03/11 Ecocirc Pump $189.25 7 Solar PV Amazon 10/10/11 two 20 W Solar Panels $156.48 8 Hydronics Houseneeds 08/25/11 Fittings for pump station $97.25 The largest most expensive purchase, by far, is the panels at about $3000.  The good news is that EcoDirect has very reasonable shipping at $130.  The same shipping from AltE would have been over $1000.  It is also worth noting that the price would have been a lot lower if I could have used two 4×10' panels rather than three 4×6'. The second most expensive item is the solar hot water tank.  At about $1800, the price might be more than a little surprising to anyone that has purchased an electric hot water tank for, say, $400.  But there are two things to keep in mind.  First, this tank has a heat exchanger inside so I didn't need to configure an external heat exchanger and a second pump.  Second, this is a stainless steel tank that should last more than twice as long as a standard steel tank.  At least that is what I am hoping and the lifetime warranty makes me believe. Items 3,4,5, and 8 basically make up all of the Califfi Solar Pump station including the pump, controller and fittings.  This is a whopping $1,352 which seems like an awful lot for what it does.  The Caleffi equipment is nice, but it seems grossly overpriced.  Caleffi does nicely put all the little plumbing components (check valve, pump, temperature gauges, pressure gauge, air bleeder, fill ports, controller) all into one nice little package.  But the price will make the budget conscious person think about making there own system instead of buying from Caleffi. Item 6 is me having to buy the pump a second time because the Caleffi pump really isn't the right one for the job.  I have listed the old pump on ebay and Amazon and hope to recover some of the money Item 7 is the solar panels, which were also purchased twice for this job.  First I bought two 10 watt panels and then discovered that they were too small, then I bought two 20 watt panels.  Also, my insistence on using solar electric power contributed greatly to the cost of this system.  In addition to the cost of the PV panels, the pump is more expensive and the controls and electronics are more complex.   It is no wonder that AC power is used for most of these systems. All-in-All, these main components represent only 50% of the total system cost.  The "balance of system" or other parts cost just is much which is shocking.  I will cover those costs in a separate post.

Laing Eco-circ pump

   It was probably too much to expect everything to work perfectly and it hasn't.

   When the Laing Eco-circ pump turns, it is designed to use as much electric power as possible from the solar panels (PV).  Unfortunately that causes the system voltage level to drop to 17 volts and the battery charge controller stops working and eventually the controller would shut down due to lack of power.  A secondary problem is that the pump is circulating the water too fast.  It is pumping well in excess of 5 gpm (gallon per minute) which is much faster that the 2.5 gpm that is recommended by Heliodyne for the solar panels.  Too much gpm and using too much electricity.

    So I contacted Laing technical support (which appears to be Xylem Inc part of ITT) and got some great help from Amy Flores.  Long story short, it looks like Caleffi made a mistake by using the D5 "strong" pump.  That pump is really intended more for maximizing flow of fluid which is not what you want in solar hot water panels.  It is probably great for well water pumping, but not for solar hot water panels where flow control is needed.

   Fortunately Laing makes an Eco-circ D5 "Vario" pump which has, as the name suggests, variable flow settings.  There is a dial on the side of the pump where you can adjust the volumetric flow.  The image shows the two different pump types.  On the left is the "strong" pump that pumps the water as fast as possible.  The pump on the right is the "vario" version with a small red dial that allows the flow to be adjusted and save some electric power as well.

 The design of the eco-circ is really excellent.  The pump/impeller side can be easily separated from the involute/pipe fitting side.  This allowed me (really Amy gets credit for this idea) take the new motor and attach it to the Caleffi fittings (which are custom).  So I took half of one eco-circ and screwed it to the other half of a second eco-circ pump to get what I needed.  The "vario" pump was purchased from Sun Volt Energy (www.sunvoltenergy.net) for $179 which is an excellent price considering I paid $325 for the Caleffi pump.  Sun Volt got the pump out to me in just a couple of days which was great.  The image shows the two halves of the pump.

 As can be seen in the picture, the official part number for the "Vario" is D-38/710B.  I found the Eco-circ part numbers to be confusing.

  The Results:  This is the best part.  Using the dial, I could adjust the speed of the motor until I had 2.5 gpm flow as shown in the picture.  I give Caleffi credit for including this nice flowmeter into their pumping station design.  Without the flowmeter, I would have no idea what kind of flow I was getting.

   Now for the best part, connecting the pump to a power supply and the power supply to a Kill-a-watt, I found that the power used is only 9 watts versus the 50 watts used by the old eco-circ pump.  Can't wait to see if it works as well on sun-light power.  Think about it for a minute. 2.5 gpm for 9 watts!  Many home circulators require more than ten times the power to do the same job.  Well done Laing.

   The hot water tank still needs to be connected to the domestic hot water system.  Hope to do that soon.  A plumber is coming tomorrow to look at the system and another plumber said he would do it for $1100.  I would prefer to do this myself, but officially, only a licensed plumber is supposed to do the job.  The whole project has turned out to be way too expensive.  However, I must complete the project at this point to be done with it and get the benefits.

Furnance Duty Cycle

   The primary motivation for putting in the solar panels has been to reduce oil consumption and the ultimate success or failure will be judged by the oil savings.

    But measuring oil consumption is slightly difficult and very low resolution.  The truck comes to your house and fills the tank about 8 times per year. It is difficult to know how much oil is used in any given month and you can forget about seeing any consumption data on a daily basis in a way that is easily possible for metered products like electricity.

   However, I have found another way to measure oil consumption.  The technique has two parts.  First, the furnace supposedly uses 1.0 gallon per minute when it is on.  Secondly, there are data recorders (data loggers) that can measure when a motor is on.

   The data logger that I used is called a HOBO from manufactured by a company called Onset.  This is a great product.  You can log one year's worth of data.  It only uses one CR2032 watch battery, attaches to the motor with a magnet, and remotely senses the motor state based on fluctuating magnetic fields.  It has a USB port and the data can be downloaded to the HOBO software.  It is about $100 for the data logger and another $100 for the software. 

  What was a slight pain was parsing the data in Excel.  What I really want to know is Duty Cycle, or the percentage of time that the furnace is on in a given day.  What I start with is a bunch of time events that indicate when the motor turned on or off.  I spent a few hours writing a VBA macro in Excel to parse the data the way I wanted.  The biggest problem is splitting events that happen just before or just after midnight.  But the result is just what I wanted.

The chart is a little complicated so let me walk you through it.  On the horizontal axis is time, about one year starting at the beginning of heating season around October 7.  The black dots are data points for the duty cycle.  If the duty cycle was 50% it means that the furnace was firing half of the time.  I have almost a full year's worth of data.
   Since the data is a little noisy, I fit it with two curves.  One curve is parabolic and represent the heating season.  The second curve is linear and represents the summer season.  This gives a clearer representation of the two uses of the furnace 1) domestic heat, and 2) domestic hot water.  It seems reasonable to assume that the domestic hot water is fairly consistent throughout the year.  In fact, it looks like there is a baseline usage of about 5% or roughly 1 gallon of oil every day.
    The oil usage might rightly be broken down into three usage
1) Domestic home heating
2) Domestic hot water
3) Idle losses
Even if no one was in the house and it was summer, my furnace would still consume oil due to the old fashion "tankless" water heater.  The tankless heater requires the furnace to maintain temperature 24/7/365 just in case someone wants some hot water.

    It is difficult to separate hot water usage from idle losses so I have grouped them together in one group in the graph.  Hot water and idle losses represent about 40% of the oil consumed or 377gallons.  Of that, probably half is hot water and half is idling losses.  So a big win for the solar hot water system will be for it to make enough hot water to allow me to shut off the furnace in the summer.  If oil is $4/gallon, then 377 gallons/year means $1508/year, but I will never achieve that much savings because it is not sunny every day and I am not sure how to automatically shut the furnace off and I might also need to bypass the furnace to get this system to work, something I have yet to figure out how to do. Step-by-Step.

  For domestic heating, an estimated 555 gallons (60%) are used per year.  So perhaps I should have spent my money on a more efficient furnace rather than solar water heater system.  But then again, perhaps I can do the furnace upgrade in the future.

  The estimate shows about 932 gallons/year total oil consumption.  This number is quite good because in the 2009-2010 season I used 942 gallons, so the estimate might be within +/-5%.  The insight gained from the data logger information more than makes up for the possible +/-5% error.

   Hopefully in a year, we will have lower duty cycle numbers to share with you.

Up and Circulating

Once all the plumbing was in place, I was more than a little nervous about whether or not the system would hold pressure.  One bad solder joint could make my life very difficult.  So I set about the process of filling the system.

In order to fill the system, I purchased a 1/2 hp "jet pump" that is used for wells.  The pump would be used to draw water (or propylene glycol) from a bucket and pump it into the system.  Of course, like everything else, this meant taking a trip to Home Depot to figure out the appropriate fittings.  The inlet of the pump was a massive 1 1/4" NPT thread but the outlet was only a 3/4" NPT thread.  These would need to be adapted to "hose bib" fittings.    I found a 1 1/4" to 3/4" adapter so that the inlet and outlet were now both the same and I also found two 3/4" npt to 3/4" hose bib adapters.  Also purchased a couple of washing machine hookup hoses to connect the pump in to the solar pumping station.

  The water could then be pumped out of the orange buckets and into the system.  The fluid was then returned back to the bucket in one continuous loop.

     Unfortunately, I had two leaks. SIGH.  The first leak was between two of the solar panels.  It looks like I was not careful enough when installing the panels and one of the o-rings got pinched between the brass surfaces.  The o-ring was damaged and had to be replaced.  The second leak was one of the copper unions that I had placed above the hot water tank to facilitate service.  This union had a large open pore (void) in the surface where sealing was to occur (Thanks Cello).  So I purchased a new union from Home Depot for $17 rather than the $9 I had spent on-line for the other ones, but anyway it was replaced.
    Now to deal with the broken O-ring.  After having spent more than $3000 with Heliodyne, you might think they would have included a spare O-ring, but no.  Strike 1.  But should be simple enough to find a replacemtn.  It is a 1.250×3/32" o-ring.  So I go to Home Depot, Strike 2, they only have o-rings for kitchen faucets.   Go into work where there is a huge selection of o-rings.  There is a 1.250×1/8" but no 3/32".  Strike 3.  Drive to Sears Hardware in Ashland because I knew the Sears Hardware in Delaware (near where I formerly worked) had drawers full of o-rings.  But Sears Hardware Ashland doesn't have o-ring drawers.  Strike 4, but the Sears salesman does give me a tip to look at Ace hardware (which was closed at the time).  On the way home, I went to Lowes which also does not have o-rings despite the Lowes salesmen sending me on a wild goose chase. Strike 5 with four hours wasted.  The next day, I went to Lexington Ace Hardware near my house and purchased the needed o-ring for 59 cents.  Sigh.

   With the leaks fixed, I charged the system with water and it held.  Then I flushed the system with a water and TSP (tri-sodium phosphate) cleaner for several hours.   Next I flushed TSP out of the system with 20 gallons of clean water.  The jet pump moves the fluid at more than 5 gallons per minute.  Very impressive to see a 5 gallon bucket emptied that quickly.

   One small problem is that the flowmeter on the pumping station stopped working some time during this process.  The flushing had liberated some steel (or aluminum but not copper) shavings that got caught up in the flowmeter.  That required removing the flowmeter and removing the metal with tweezers.  Put the flowmeter back in and things were up an running.

Circulating on its own.

  It is all very well and good to use the charge pump, but the system should function with its own internal DC eco-circ pump.  First several attempts to do this failed.  There did not seem to be enough power coming from the solar panels.
     The process was very frustrating.  The eco-circ has its own built in controller that only takes as much power as is available from the solar panel and can supposedly run on as little as 8 watts.  Since I had a 20 watts of solar panels, it seemed like the pump should run.  The power from the solar panels was sent to both a charge control AND to the pump (switched through a relay).   My hope was that the charge control and the pump would each only take what they needed and share the power.  But this may have been a vain hope.  Even directly connecting the solar panel to the motor didn't seem to work.  I think there just is not enough power to get the motor started.  Even if the pump motor might be capable of running from 8 watts, perhaps it cannot start from 8 watts.
   So I needed a new plan.  One quick trip down to You-Do-It Electronics in Natick and I was back in business with a 50 W 24VDC power supply.  This did the trick and the pump started moving.  However, it was unreliable.
    Quickly I figured out that the problem was with air in the lines.  There are two air traps in the system which work great, except they can only do their job if the water is circulating.  Unfortunately, the water could not circulate because there was too much air in the lines.  Specifically, there was air trapped in the space where the motor impeller is located just before a check valve.  So there is a Catch 22.  The air traps cannot do their job if the water is not circulating but the water cannot circulate if there is air at the motor.

     By trial and error I found that by increasing the pressure  in the system (using the external charging pump) I could get the small circulator pump to start the water circulating.  The system has a flow meter with a glass window and massive quantities of air bubbles could be seen moving around.  Eventually, the bubbles worked their way to the air traps and could be purged from the system.  Then the some water was drained from the system to get the water pressure back down to about 12 psi.  All and all, I was happy to get to this point.  The system was holding pressure.  The water was circulating.  Not only is it circulating but it is circulating at more than 5 gpm (gallons per minute) which is twice the necessary 2.5 gpm.  Unfortunately it is taking 50 watts to get to 5 gpm, but hopefully it can get to 2.5 gpm for 25 watts.

    Clearly larger solar panels are needed so I ordered two 20 watt (40 watt total) solar panels from Amazon for $150 with $3.99 next day shipping..  Hopefully this will fix the issue with the pump.  I debated getting larger panels (like 60 watt total) but I really shouldn't need that much.


The Installation Tour

   So let me give you a tour of the installation now that it is almost complete.

The image above shows the South wall of my basement which contains most of the inside solar equipment.
1) Solar pumping station.  The front of this is the differential controller responsible for turning on and off the pump at the right time.  It is connects to thermistors (temperature sensors) on the solar panel and in the hot water tank.  Behind the controller is the pump and a large number of other components.
2) These Taco zone valves, when open, allow water (heat transfer fluid really) to flow to the hot water tank.  I doubled up on them to increase the amount of flow but in hind-sight this was probably unnecessary.  Although the connections to the valves are 1" the valve itself is probably less than 1/2".
3) These Taco zone valves, when open, allow water to flow to the heat dump.  Again they are doubled up.
4) This box contains A) charge controller, B) 24 V NiMH battery, C) 24 VDC to 12 VDC converter, D) some relays.
5) Some additional relays were needed to turn on the pump.  Unfortunately the controller is 12VDC but the pump is 24VDC so some relays were needed.
6) Expansion tank to take up the extra fluid when the water expanses when heated up.
7) These two pipes connect the pumping station to the solar panels
8) These two pipes connect the pumping station to the hot water tank.

  The picture above shows the 1/2 hp jet pump used for charging the system with fluid.  The fluid comes out of the bucket and is pumped into the solar system.  About 10 gallons is needed to fill the system.  The charging system is temporary and will be removed once the system is commissioned.

     The jet pump connects to the fill and drain ports on the solar pumping station (shown above) using garden hoses.

  Looking at the installation from another angle, we can see the solar pumping station (1) on the right, the piping (2) above, and the hot water tank (3) on the left.

       The overhead piping needed to be supported.  But most brackets would crush the insulation.  So I cut out a piece of aluminum (8x4"), painted it black, and placed it underneath the bracket to spread the load.  I also painted the bracket both black and white to match the insulation and ceiling as needed.
  

   On the other side of the room is the hot water tank.  The 80 gallon tank is manufactured right here in Massachusetts by Heat-Flo which is pretty cool.  There are a couple of nice things about the tank.  Firstly is that it is made of stainless steel which should assure a very long life time.  Secondly, all the connections are on the top of the tank which makes for a very clean installation. 

   The connections through the top of the tank were made through copper unions and full port valves. This setup allows the tank to be isolated from the rest of the system for servicing.

The wire for the thermistor was routed down the front face of the tank and secured with cable clamps that I pop-riveted to the plastic outer shell of the tank.

  Lastly, the solar PV panels were temporarily attached to the hot water panels using some 2x2" pressure treated lumber.  I felt there was a good chance that they would need to come off again, so I didn't attach them more permanently.  They will soon be replaced by larger panels and if those work out I will get some aluminum extrusions on which I will mount them more permanently.

  Next step, see if I can get Sweet Plumbing in to connect the hot water tank to the domestic hot water supply.

Plumb, Plumb, Plumb away.

With the pumping station and solar panels in place, all that remained was to get the hot water tank and piping in place and that is what I did.

  To make sure that the heat dump was well soldered, I put together a pressure test gauge as shown in the picture.

The gauge uses a tee that connects 1) pressure gauge, 2) tire valve stem, and 3) the pipe under test.  In this case I used "shark-bite" fittings from Home Depot.  The "shark-bite" fittings slide right on to the end of a pipe, but cannot be removed without a tool.  To check the integrity of the pipe, I filled the heat dump with compressed air.
     I found that overnight, there was some slight loss of pressure which was worrying.  So I decided to mostly fill the heat dump with water and then add air to create pressure.  This revealed that some leaking was occurring in the 1/4 NPT fittings.  Once I tightened the fittings, the leaking stopped.

    Plumbing is not difficult work, but it requires patience and attention to detail.  There is a lot of measuring, cutting, deburring, sanding, dry-fit, mark, disassemble, flux, solder, cool, clean, and repeat.  The parts have to be absolutely clean.  Flux needs to be applied to every square millimeter of both mating surfaces and solder must be applied to the full 360 degrees of the joint.
    The images below will give you a sense of the process for the return line for the solar panels.

    The first part of the piping required a 180 degree turn which I made with two "long radius" 1" copper elbows.  Those connected to the solar panels via a union (half) that was purchased from Heliodyne.  The union connects to the panel using an O-ring so that it can be disassembled easily.  I sloped the pipe leading to this area down in this direction.  If I need to drain the system I can just disconnect the union from the panel.  I considered adding a drain valve at this location, but I didn't.  

 That pipe connects to a second using a 90 degree long radius elbow.  These "long radius" elbows create dramatically less flow resistance than a standard elbows.  The pipe is then routed up at 45 degrees right underneath the panels.  I worked to minimize the visual impact of the piping by hiding them behind the panels.

 The pipe then transitions through a 45 degree elbow toward the house.

 

That pipe goes straight through the one of the holes in the sills.

 And then sticks into the basement.

 And curves down to the pumping station mounted on the wall.   The special high temperature/UV resistant UT Solaflex Insulation that I purchased from "Alt E" was not slit.  The insulation had to be slid onto the copper tubes which presented a bit of a logistics problem.  The joints in the 6' long insulation tubes had to be planned to be near solder joints.  The insulation could be compressed away from the jointed and held with a clamp during soldering.  To aid in installing the insulation, I applied baby power to the copper tubing and then slid the insulation onto the pipes.  The "long radius" elbows made it quite easy to make the insulation slide around the turns.  However, it is easy to poke your finger tip into the insulation, so I learned to work mostly with my palms.

 After soldering, the insulation could be pushed back into position.

 That should give you a better sense of the plumbing process.  The same process was repeated for the supply line to the solar panels and then connections made to the heat dump and the hot water tank.

   Speaking of the hot water tank, there is my buddy Doug dropping it off at my house.  Better go help him unload it.

And Let the Piping Begin

   Well it had to happen sooner or later, I put to big holes in the side of the house.  But it wasn't as easy as I thought it would be.

   I purchased a type of holesaw called a SwitchBlade.  It is a neat design with replaceable blades.  There were two problems.  First, given the 2 9/16" hole that I was trying to drill, the shank required a 1/2" drill, which I have.  Unfortunately, the switchblade does not just cut the outer edge of the hole, like a traditional holesaw, it removes the inner material as well.  Which brings us to the second problem, the drill didn't have enough torque to drive the bit.  So the bit kept getting stuck.  As can been seen in the pictures, I tried making Swiss cheese our of the middle of the hole with a smaller bit, but this didn't help.  So, a $50 drill bit was set aside and back to home depot I went.

    Starting with a 2 1/2" hole saw that I owned. I managed to drill out the rest of the hole without stalling our the drill.  The important thing here is that a traditional holesaw does not grab.  So you can cut slowly.  Also, energy is only being expended at the outer edges of the hole and the middle is left alone.  This makes drilling more rapid.
   With the 2 1/2" hole drilled, I was a little worried.  I actually needed 2 3/4" hole, but now wasn't sure I could even use a bigger holesaw.  Holesaws work from a center pilot drill bit, but the center of the hole was missing, so no piloting.  But I purchased both a 2 5/8" and 2 3/4" bit and found that I could get them to enter the existing hole and have them self pilot based on the hole edge.  Success and another $50 spent for a total of $100 to make two little holes.
   What made this a little difficult was that I had to drill through the sill which on my house appears to be one solid 4×8.  They don't make them like that anymore.

    Supporting the pipes will be a little bit of a challenge.  Looking on line, I found no less than 12 different types of pipe hangers.  None of them seemed appropriate for supporting an insulated pipe.  Most pipe hangers support the pipe over a very narrow width.  If I did that with the insulated pipes, then the insulation would get crushed.
   So I decided to design some of my own supports out of bent aluminum sheet metal.  The image below shows one bracket that I used on the return pipe.  It cradles the pipe right up next to one piece of Misumi aluminum extrusion.  The support is 8" long and can spread the pipe weight over a long enough area to avoid insulation crushing.

   Then an alternative design was made for the supply pipe.  This is effectively a U-shape which I hung off of a short piece of 40×40 aluminum extrusion.

    The same design was used in a second location to support the supply pipe

    Frustratingly, I still don't have the long radius elbows that I ordered from PexSupply.  First they sent me the wrong parts, then the next order was held up due to some back ordered parts, and when I finally pushed them to ship the 90% of the order that was in stock (including the elbows), they had sold my elbows to someone else and the elbows were out of stock.
      But as it turns out, there was at least one pipe that I could get started on that didn't use the missing elbow: the supply pipe from the solar panels.  The supply pipe from the solar panels serves a could of different functions.  As it happens, this is always the highest point of the system, so it is important to put an air bleed valve there.  However, apparently these valves have a nasty habit of failing.  So just before the air bleed valve, it is recommended that you place a 1/4 turn shut off valve as can been seen in the picture.  Both the air bleed valve and the 1/4 turn valve came from Caleffi and are specially made for solar applications.  Although these items can be purchase from a place like Home Depot, they will not be rated for 275F or outdoor use.  These items were attached to a special elbow sold from Heliodyne.
   Also at this location, the temperature of the solar fluid must be measured.  So Heliodyne makes a special will "well" piece into which a thermistor can be placed..  I have not installed the thermistor yet, but when I do, I hope to run the wires inside the pipe insulation which should make for a very clean install.

 

  The first section of pipe was soldered together and is supported by one of the custom brackets.

 

   Also, the solar hot water thank is on order.  I chose an 80 gallon stainless steel models from Heat-Flo (HF-80).  It is expensive at $1800 (with shipping) but hopefully it will last forever.  I was really torn because A.O. Smith model SUNX-80 looks excellent.  It has less than half the flow resistance of the Heat-Flo.  If I recall correctly, the A.O. Smith model was equivalent to 18 feet of 1" pipe, the Heat-Flo was 60 feet, and the SuperStor was 250 feet.  I was amazed by how much difference in flow resistance exists between the different hot water tanks.   Hopefully I can get the 2.5 gpm flow rate that I need despite the high resistance of the Heat-Flo tank and the Taco Sentry Zone valves.

Hang that Heat Dump

  Initially I was just going to hand the heat dump form a couple of simple pipe hangers until I got concerned that it might pull out of the wall under the weight of the water.  But I might have gone a little to far in the opposite direction.

    Using Misumi 40×40mm extrusions, I constructed a couple of ladder type of supports that cost a total of $200.

   Using a Bosch hammerdrill, I made some 3/16" holes in the concrete and fastened the aluminum extrusions to the wall with tapcon concrete screws.  To get the two supports level. I used my laser level which you can see in the picture as a faint red line.

   The laser line was lined up with the screws of the first support, again with the faint red line.

    With the supports in place, the heat dump could be mounted to the wall.  So the aluminum fins don't get dented, plastic support pieces were placed between the Misumi aluminum extrusions and the radiant heaters.  The plastic pieces come with the radiant heaters and fit well on the 40 mm extrusion. 

   Only gravity is holding the heat dump in place, so thermal expansion should be easily accommodated.  However, the heat dump is fully captured by the aluminum extrusions and cannot fall off the wall.

Painful Shopping Day

   Gave myself a three day weekend to make progress, but I am afraid that all I accomplished was updating my model and shopping.  And boy did I spend a lot of money.

  $200 at Home depot for the 1" L copper tubing.  I know that getting the thicker (L versus M) and the larger diameter (1 versus 3/4") would cost more, but boy.

  $74 for a Caleffi expansion tank.  I already have a new Watts tank and planned on using it.  But the Caleffi pump station is setup for a 3/4" straight fitting and I couldn't figure out how to adapt it to the 3/4" NPT on the tank I have.

  $329 at PexSupply for all the 1" fittings that I need and I am also ordering 2 more Taco Zone valves to put in parallel with the ones I already have.  The taco valves are not "Fully Port" valve and have a great restriction which may kill the flowrate (GPM) in the panels.  On Taco valve is equivalent to adding 45 feet more pipe in the system.  Putting two in parallel should at least cut the resistance in half.  I won't know if this is worth doing until I get the system up and running.  Decisions, decisions, decisions.

   $400 at the Alt-E store,  $200 for the high temperature/UV resistance (armacell Solaflex HT) pipe insulation and $200 more for four gallons of propylene glycol.  So the contents of the pipe are $200, the pipe is $200, and the insulation is $200.  I didn't expect it to be this expensive.

   Getting close to the end.  I would still like to have HT 625 armacell adhesive and most importantly a $2000 hot water tank that I still cannot decide on.  It turns out that some of the good tanks have very high flow resistance through their coils.  Now I need to rethink.

Building the Heat Dump

  Once the hot water tank is full of hot water, one limitation of this type of solar system is that you must contend with unwanted heat.  If the propylene glycol/water mixture is left in the panels, it will overheat.  This can breakdown the propylene glycol and blow open the pressure release valve.  To avoid these problems, I am using a heat dump.

   From some dude on Craig's list, I purchased about 70 feet of baseboard radiators for $120.  These pieces are new and left over from plumbing jobs the gentleman had worked on.  I decided to run the radiators in parallel to reduce the flow restriction.  The heat dump consists of 10 parallel sections each 7 feet long.  This really should be overkill for this job.  But I wanted to make sure that I could shed the energy from a midday summer sun.

    I built the heat dump in two halves.  In the image below, you can see the front half.  The radiators are spaced at 5" from each other.  This plumbing is done with 3/4" copper sweat joints.  I created a wooden fixture to make sure the spacing and angle of the header pieces were just right.  Otherwise I might not have been able to assemble the finished halves together.

   The front and back halves were jointed together at the top with a 3/4"x1"x3/4" tee.  In this way the fluid can flow into a large 1" opening and then split into two 3/4" sections.  This should minimize flow restriction.  In the image below, you can see a "baseboard tee" which is really an elbow with a 1/8" npt female thread at the corner.  I am planning to put an air trap at that location.  There is a similar fitting at the bottom that will be used as a drain.

The completed assembly consists of about 60 solder joints and weighs 40 pounds (dry).  I need to pressure test it and then mount it on the wall.

 

Any guesses on how hot my basement will get when this thing is turned on?

The Panels Are In

   My three Heliodyne Gobi 406 001 solar panels arrived at my work the other day.  It was quite the event.  Work is in downtown Brookline Massachusetts which has very narrow streets.  Fedex Freight showed up to the site with a truck that was too large fit into our loading area (height restrictions) and no liftgate.   Fortunately we had interns.  Lots of interns.  They kindly helped me unload the panels and then reload them into my friend Doug's Ford F-150. 

    Of course I give my friend Doug crap for commuting to work in an F-150.  He drives at least one hour each way and probably only gets about 15 MPG.  Really kind of ridiculous.  But on days like this, I am glad he has the truck and willing to help out.

    The panels were shipped to my work to avoid added shipping fees.  When freight companies ship to a residence, they can tack on a $100 fee for the added difficulty.  They may tack on an additional $100 fee for a liftgate (sort of an elevator on the back of the truck).  To avoid these fees I shipped to a business address.

    One surprise with the panels is they are a full inch thinner than expected.  The panels were supposed to be 3.8" thick but are only 2.8" thick.   Apparently Heliodyne has come out with a thinner product line that is designated with "S".  So technically the panels are 406001S even though I ordered 406001 and the panel label says 406001.  It is frustrating to have that uncertainty in the ordering process, but in this case, it didn't do any harm.  In fact I think the thinner panels look great.

    The panels are so thin, that when Doug saw them on the truck he said there is only one panel, where are the other two?  Well all three panels were strapped to one oversized pallet, but with only 8.4" total thickness, he thought it was a single panel.

    The panels had to sit in my garage for a while, because I had not ordered the appropriate clips from Heliodyne.  Upon trying to order the clips, I found it almost impossible to figure out.  Alt-E (on-line store where I bought the panels) could not really help.  I think if you buy the Heliodyne racking system, they give you the clips.  But if you have made your own rack (like I did from Misumi extrusions) then you are on your own.

     So I decided to design and make my own clips out of stainless steel.  They are a pretty simple parts.  They only clamps down on the edge of the aluminum frame of the panel and have holes in the center for an M8 bolt. 

  To make the part, I milled one long piece of stainless steel on the bridgeport with the appropriate profile.  Then I came back and drilled the hole and cut off the individual parts.  The machining is less than perfect (as seen in the picture)  but it should work just fine.  Total machining time was four hours, which is way too long, but I am still learning my way around a bridgeport.  I was proud to be able to make them myself and the part is very sturdy.

   With the clips in hand, mounting the panels on the frame was quite straight forward.  Unfortunately I don't have a good picture because I immediately covered the panels with cardboard and tarp to avoid them over heating.  But trust me, the panels are under there and look great.

Rocks, Rocks, and More Rocks

   Sometimes I get a little depressed with the slow progress that I make on this project.  But then again, I am still glad to be doing it myself rather than simply writing a big check to a contractor.  Doing things myself provides a level of understanding and a sense of self worth that cannot easily be described.  In any case, I am marching forward.

   The work-site needed some cleaning up.
1) Remove the concrete forms.
2) Lower the dirt grade about 2" so that a rock finish could be added.
3) Put down weed-stopping plastic.
4) Put in plastic edging to define the zone
5) Add river stones
6) On the other side of the sidewalk, restore some top soil, add grass seed and fertilizer.

 The result of this effort, and hopefully you will agree, is a dramatically cleaned up look.  In fact it may be the best looking part of the landscape on the whole property

    On each end of the solar panel area, a small dirt area has been created for planting some greenery.  Hopefully this will offset the very industrial look of the installation.  The plants must not be too tall, however, or they will block the sun from getting to the panels.  I am considering hostas  but I don't know if they will work at this sunny location.

    The forms around each concrete pier have been removed.  I think they look pretty good.

   The site is ready for the panels.  I have even taken the tarp down now to get it out of the way of Hurricane Irene.

Putting the Sidewalk Back In.

     Life (and engineering) is full of compromises.  To put the solar panels at the location that I wanted them, I had to take out the sidewalk.  This was a ton of work and I would have loved to avoid it.

    Sadly, it was only half the work.  Now I need to put the sidewalk in at a new location.  There has been nothing but dusty dirt there for a while, and I cannot believe how much dirt has been tracked into the house.  It is time to fix that.  Also I would rather get the concrete in before the panels go in, rather than the other way around.  Seems like mixing concrete so close to new solar panels is a bad idea.

   To get started, I had to dig out about six inches of soil and cart it away in a wheelbarrow.  Then I had to put in forms made out of 1x3 strapping with stakes holding them in place about every 25 inches.  I worked to match the slope of the soil on the grassy side of the walkway.  If the sidewalk is too low, soil will wash on to it if it rains.

   With the forms in place, I went over to Home Depot and purchased 1000 pounds of gravel.  I took two trips in the Corolla so that I didn't risk overloading the suspension.  I would hate to break a spring in the process of doing this project.  The level of the gravel was flush with the bottom of the form so I would have approximately 3" thick concrete when I was done.

   To hold the concrete together, I added, so called, six six ten ten mesh.  This is steel mesh of 6 inch squares with ten gauge wire.  I purchased a small pair of bolt cutters to cut the material.  Bold cutters are so cool.  I wonder if I will ever use them again.  When I poured the concrete, I periodically pulled up on the mesh to get it in the middle of the concrete.

     Starting at 6am, I went to work.  I made two trips to Home depot to purchase 24 bags (80 pounds each).  That is a total of 1920 pounds or just short of a ton.  The bags of concrete were in place on the site just before 8am.  That is my son in the picture, but he was heading out to Maratha's Vineyard with the girlfriend for the weekend.  So no help there.  I am not complaining.  I am glad he went.

  And so it began.  Pour the concrete into the wheelbarrow, add water, mix, dump into forms, compact, screed, float, trowel, edged, add brushed finish, repeat, until just about noon and it was done.  I had two bags of concrete left over which I returned to Home Depot because concrete does not keep well.

  I am very happy to have the concrete in.  I am not sure I like the surface finish that I left on it, but I will know better once is hardens.  I wanted a little bit of texture for traction.

   Underneath the solar panels, I would like to add a stone bed.  I think this will be good for keeping down the weeds.  By next weekend, the three solar panels should be here.  Actually, they should be at my work because if I shipped them to my home there would be a $200 added charge.  Hopefully my buddy Doug will help me get them home using is big F-150 pickup truck.