Progress

I'm not finding much time in the week to work on this, but I've made good progress nonetheless.  Most of the downstairs plumbing is completed.  The plumbing that is hooked into the house water supply is all sweated together and in operation.   The solar storage tank is now passing unheated water to the water heater.  All it needs now is have the solar heat exchange fluid (distilled water) pumped through it's heat exchanger.

The combination of short work windows and the need for hot water in the house made for some stressful times. I created a few leaks that were hard to put right.  Calling my friend Colin the Plumber was the right thing to do.  It was expensive, but I learned a lot watching him work.

Here's a incomplete list of mistakes I made:

1. I sweated in two swing check valves.  They sweated into the system no problem.  Every time the washing machine demanded hot water with it's solenoid actuated valves it caused the swing valves to bang really loudly.  I would never suggest to anyone to use this type of valve.  Colin replaced them with valves that close quietly.
2. I failed to read the instructions for plumbing in the Watts tempering valve.  On the cold inlet side you HAVE to have 8" to 12" of pipe coming up vertically into the valve body for it to work.  If you don't do that you only get cold water.  None of the hot supply is passed.  This is probably a good way to fail as passing solar heated 175 deg. water would be really bad.  However, it caused me to call in a plumber in the night to put in a ball valve on the cold supply side of tempering valve, until time could be found to plumb it correctly.  This was an expensive, stupid mistake.
3. You should always use PTFE tape on pipe threads WITH pipe compound.  Tape first, then apply a generous amount of pipe compound.  I'll never go back to using only PTFE tape...
4. I did not use two unions on the top of the SunEarth tank.  To begin with, I used none.  Because I had a leak on the pipe nipple on the inlet side (See mistake #3), I fixed that and put in a union.  The other side is not leaking and had no union, so when it comes to time replace the tank, it will need to be cut out.  At that time a union should be installed.
5. I used a pressure relief valve that I had laying around on the solar storage tank, not the 210F PRV that was supplied by Solartrope.  That probably won't be a problem, but we will see....

Whew!  This phase of the project was Trial by Leaks!  I always want the second or third iteration of whatever it is I'm making, so I expected mistakes...

Solar Storage, Pump, Drainback Tank

The solar collector loop is still unattached on the roof.  It's sweated together in the garage and presumably I could test it by pumping water up to the rooftop.  It wouldn't be a full pressure test, but it would be interesting to see if the pump is capable of lifting the water up there.  I'll be pretty grumpy if it's not.

There's lots left to do, but the hardest bits are done.  The biggest deal is racking the panels.  That I hope to do in the next couple weeks.  If all the plumbing leaks are over and done with (big if), then most of the rest of the work is insulating pipes, hooking up the controller, and lots of little things. Little is good =)

Hot Water Heater, Tempering and Other Valves

Check Valve

Today I worked for an hour or so adding a swing check valve upstream of the three way valve.  The top of my storage tank has a nice spattering of solder.  It relies on gravity to stay closed when water is not flowing in from the cold supply.  Like the double wall on the heat exchanger, this is another system component that  ensures that water will never work backward into the city water supply.  The unsoldered 90 between the labelled ball valve and check valve will actually be a couple 45's which will clear a the upper vent pipe in the background without resorting to 180 degrees of bends.  The less pressure drop around this system, the better!

Valve Manifold

Last night I started plumbing in valves and pipe on the top of the SunEarth 80 gallon storage tank.  I took it slow as making a mistake here would be messy and slow to undo.  I cut and pieced together all the fittings, sliding the tank back against the wall to make sure that the manifold cleared the 4" vent pipe that it needs to fit beneath.  Then I trebly checked the valve arrangement against the system schematic.  This was made slow and somewhat confusing because the component placement and orientation of my schematic differs from how the system is actually coming together.  Below is the manifold all sweated together.

With any great luck all the sweated fittings are water tight.  Going copper to copper is easy for me.  Going from copper to chunky brass and bronze valves has caused problems for me in the past.  I've had ball valves `pop' apart into two pieces hitting them with too much heat.  They've leaked horribly when not heated enough.  So, I made sure to first diligently clean them with a tubing brush, flux, then I hit them pretty hard with heat and used plenty of solder.  To keep the PTFE valve liners from melting, I used a wet towel to bring the valve bodies down below 100 C immediately after sweating on the fittings.  Only putting this all under city water pressure will I be sure that I did a proper job.

In the back, upper left gloomy portion of that picture I added a ball valve above the drainback tank.

A couple week ago, I sweated and secured the piping in the attic.  I've not yet flashed it in and the panels are still just sitting on the roof propped up on bricks. I hope to bring in a buddy from GRID Alternatives to help me rack the panels "real soon now".

 Here's a pic of the secured pipes in the attic.  The `From Collector' pipe looks like it has a section of it that is not sloped enough to allow drain back.  It actually is, but the picture would have you believe otherwise.  Until I've run water through these pipes, I'm not going to insulate them.  Getting around this cramped attic, with it's live knob and tube wiring and itchy piles of fiberglass is no fun, but with any luck, I'll only have to visit it one more time.

Next move is to cut into the existing cold water supply line, drain the line, add a ball valve and enough tubing to `stub out' the run to the 3-way valve in the above photo.  I'll not hook this up until I'm ready to put the storage tank in place against the wall.  When this will happen is unknown because I have to wait for my wife and child to `step out' for a bit before I can turn off the house supply.  All for now.

Pipes in the Attic

I worked on the system for ~100 minutes today.  In that time I managed to puncture the roof with the two pipes that will carry the heat exchange fluid from panels to storage tank.  The top pipe pictured below is the return and the bottom one is delivery to the panels.    That's Bayview Hill in the background for scale (hehe...).

The spacing of the pipes should work with the Oatey brand flashings that I've purchased.  I'm not sure what roofing products I'm going to use to create a sound seal around these pipes yet.  It's definitely a bit foolish to put holes in your roof before you have the products you're going to use to seal them.  This will motivate me to get those products!

The next two pictures below show the run in the attic at both the point where it penetrates the roof decking and where it comes up from the garage.    You can also just barely see the `bell' wire hanging down from the upper pipe in the first picture.  This is temperature sensor line that goes to the Steca controller.  I plan on running this through the rubber gasket on the Oatey flashing with the return pipe, then running it under the outside pipe insulation.

The above photo shows, from top to bottom, the 3/4" EMT conduit (future PV?), return and delivery lines.  That 10" galvanized stack vents our gas furnace and hot water heater. This attic is very low, full of itchy fiberglass and has knob and tube electrical lines that make an electric fence that I'm forced to limbo around.  I can't wait to be done up here!

Last Sunday my friend Mauricio and I extended the plumbing for the loop that will cycle distilled water through the panels.  We also mounted a piece of 3/4" ply to the framing I built to mount the Steca TR0301U controller.  I realized today that perhaps I should have used some kind of dialectric union between the iron pump flange and the copper pipe to avoid galvanic corrosion.  Luckily this is easy to add at this point as I haven't sweated anything into the pipe beneath the pump.

 That got me online researching what kinds of dialectric unions to purchase.  I read many opinions on DIY and plumbing forums that suggested that water temperatures over 160 F can quickly degrade your typical galvanized steel-to-rubber-to-brass union.  The hot water loop through the panels should be able to easily achieve those temperatures, so I'm left wondering what to do.  So many questions!  I have a email in with Solartrope to get resolution on this.

Next to do is hooking up the galvanized steel pipe to the cold and hot water ports on the SunEarth tank.  Again, dielectric unions will be required to transition to copper and I have the same issue of running very hot water through the unions.  My understanding is that the water in the solar storage tank will very often be scalding and that it's the mixing valve that ultimately modulates the water temperature.  

The panels are still lying on the roof awaiting my purchasing Geocel roof sealant and the right kind of membrane roofing.  It's slowly coming together...

Drainback Tank Mounted

I have mounted the drainback tank although in these pics I had yet to tighten the #6 bolts that hold the 3/4" pipe straps to the aluminum angle brackets that I fashioned. I put a couple lengths of bicycle inner tube between the aluminum angle and the copper 3/4" pipe to prevent galvanic corrosion. Tightened down, the framing, hardware and tank feel pretty solid!

This project is a lot of guesswork. The outlets of the drainback tank hopefully will be situated well for hooking up to the solar storage tank. Running copper from the collector return line to the drainback tank will hopefully avoid the spaghetti of ductwork while maintaining the required slope to achieve effective drainback. Sigh... I do not remember any of the PV systems that I've helped install over the years being this complex.

Next I'll be sweating a ball valve to the collector return line, near the ceiling joists of the garage then connecting the drainback tank inlet to that.

Situating the Drainback Tank

I scrounged two hours today between car wash-like winter storms and a mexican themed dinner that I was co-cooking for to build a stand for the five gallon SunEarth drainback tank.

The stand will have to cope with 70-ish lbs. of water and copper, so I anchored it to the existing hot water heater stand, the wall studs and ceiling joists. It's not going anywhere. The tank itself is a bit strange to mount. It can be seen in the picture as the matte black painted object in the lower right quadrant. The insulated parts do not afford a good attachment point as it would compromise the insulation. The top and bottom tubes I believe offer the best place to clamp it in place, but it will require some burly angle aluminum that I had left over from a Burning Man project and 3/4" plumbing brackets to make it work. I'm not sure how other folks do this. Part of the `fun' of this project is guessing what's required. Is this all to code? I hope so...