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.