Solar at Last

After literally years (I bought the major components in May of 2015!), we finally have an operational solar hot water heating system. Let’s start in the basement utility room.

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The collection part of the system

Here is the 800L (211 gallons) solar hot water storage tank. I choose this size on the highly scientific principle that it was the largest one that would fit under the 7½’ ceiling. The grey box on the wall is solar pump/controller. When the rooftop panel temp is higher than the storage tank temp (and the tank is less than 145 degrees) it starts pumping. The insulated pipe coming out the top of the box goes to the rooftop panels where the heat is collected and comes down though the right-hand pipe, through a heat exchange coil in the tank, then back up to the box. The red thing is an expansion tank. This system is a closed loop that has a 50/50 water/propylene-glycol mix (good down to minus 39 degrees).

solar-heat-controls

The heat distribution part of the system

On the opposite wall we have the underfloor heating pump and controls. The green box on the right is the control module. When a thermostat calls for heat in any of the 3 zones, it sends a signal to the appropriate thermal actuator (the small white cylinders atop the manifold in the center of the picture. Once the actuators are open (visually you can see a blue ring at the top) the controller starts the circulator pump (on the left — it is a delta-T variable speed pump that reacts to individual zones opening and closing to maintain a constant temperature differential between the inlet and outlet). This part of the system is a open loop — it uses the water directly from the big storage tank (which also provides pre-heated water into our small electric DHW heater.

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The collector frames

Last week I completed the assembly of the three rooftop solar panel frames. Each of the three frames will hold 30 evacuated/vacuum collector tubes. Together the three frames are about 23 feet long. At the top of each frame is a manifold — this is the only part that has water running in it, to capture the heat from the tubes.

Installation begins

Monday, the contractors arrived, two guys with two ladders. The frames are unwieldy but fairly light. After some discussion we decided to take off the relative heavy manifolds and take them up separately. Here is the first frame getting fastened to the roof; rather than put any holes in our shiny new standing roof I choose specialized clamps.[/caption]

Here is the second frame being carried up the two ladders. I am working the safety rope from underneath.

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Day one done

By the close of the first day’s installation, the contractors had completed the plumbing hookup to the frames; meanwhile I got the hookups done in the utility room. I pressurized the system with 30 psi of air and left it overnight to test for leaks. It failed the test. When the contractors got here at 8am on the day two, I put them to installing the column and posts for the ramp railing (see a few pictures down), while I hooked up the submersible pump to flush the solar system and pinpoint leaks. I had two in the utility room — both cheap-ass fittings I got at the Capon Valley Market yesterday since I ended up short. I managed to crank one down enough to stop it, and for then other I had found the proper fitting and got that in. Meanwhile, since water was dripping off of the roof the contractors went up and tightened the leaking compression fittings up there.

Leaks fixed, they started in on putting aluminum tape over the rooftop foam pipe insulation to protect it from the sun, while I drained the flush water from the system and re-pressurized it with a 50% polypropylene glycol mixture. I turned on the pump controller, and we started installing the 90 heat tubes. I was on the upper veranda unpacking the tubes from the shipping boxes, smearing thermal paste on the copper condenser tips, handing each tube up to guy one who was on the ladder, who then handed them to guy two to insert in the frames. Six of the tubes were broken, but the manufacturer was pretty generous by sending 30 spare tubes (but just the tubes, I had to remove the sealed copper tube inserts and aluminum heat-collection fins from the broken tubes).

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The finished product from the front (south side)

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And from the back (north side). To the right you can see the newly-installed posts; the shorter two are original to the house, they were part of a handrail on the front porch. I’ve been saving them for lo these 18 years — glad to have finally found a use for them!

The system seems to be working fine, the 211-gallon solar water storage tank went from 59 degrees 96 by the end of the day. Was still at 93 this morning. (I ultimately want to get the tank to 145 degrees.) This morning I turned on the underfloor heat in the addition, we’ll see how it does getting the room from 65 to 68. Also interested in whether the rooftop unit can glean heat on a cloudy day.

It feels very good to have this project done! (Well, except for some more pipe insulation in the utility room.)

And, as a bonus, I discovered that my Moto phone had made a highlight reel (complete with cheesy music!) of the photos and videos I took yesterday late afternoon. It was a gorgeous day to review the completed project from the vantage point of the pasture and spring run. And our livestock guardian dog Satie enjoyed it as well.

Addition Omnibus Progress Late Winter 2017 [Video]

Forgive me, for I have sinned: It has been almost a year since my last post.

We made good progress on our (seemingly interminable) addition project over last spring and summer. I took a lot of pictures with many blog posts in mind, but, well, «insert aphorism about the surface of a road to a bad place here», so I decided to do an omnibus video covering everything that we got done. Progress faltered, for various reasons (*cough* Trump *cough*), as summer faded into autumn. We did not meet our major goal of having the underfloor solar heat working — which would have let me continue with the trim-out over the winter — so I basically hibernated over the winter as far as the addition was concerned.

A 15-minute tour:

[Update 5 Mar 17] Fun Fact: the (will-eventually-be-) heated great room / under-loft floor has ~40 yd3 of concrete — that’s 160,000 pounds of thermal-mass goodness!

Addition Ready for Final Concrete Pour

Well, almost, still have to do the final cleanup. We are trying to arrange the final concrete pour, but with winter on the way the concrete tradesmen are very busy trying to get their outdoor pours done.

This pour is about 1068 square feet and will be 4½ – 5 inches thick. It is being poured on top of a suspended concrete slab subfloor. We want to add mica flakes at the end of the pour to add a bit of sparkle. From what we understand, this means trowel-finishing the entire floor.

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Here is the floor plan of the two slabs to be poured. Click to embiggen.

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Our lower driveway will let the concrete truck back right up to addition entryway.

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The concrete pump hoses will enter the addition via the exterior door at the top of the ramp. In this and subsequent pics you will see tools and supplies that will all be gone shortly.

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The vestibule, being closest to the door, will be the last space poured. The concrete will be poured to the top of the 4-1/2″ triple sole plate. The wallboard is already up and painted so we used blue tape and rosin paper to protect it. The space for the yet-to-be-installed 1×8 baseboard provides a space of bare studs to ease with the concrete finishing.

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Just inside the great room from the vestibule there is a staircase to the walk-out basement. The concrete finishers can use this for access as needed.

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The great room and under-loft rooms have 5/8″ pex heat tubing attached to the subfloor. At the upper right is the bow windows and at the upper left is the loft staircase the the concrete will need to flow under.

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A better view of the loft staircase corners where the concrete will go under it.

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Looking towards the loft. On the left you can see the stone chimney and the dumbwaiter enclosure.

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The galley kitchenette. Except for the bathroom toilet and shower drain, all drain pipes are in the wall.

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The view in the bedroom of one of the two closets. You can see more detail of the heat tubing — it is the zip-tied to poultry netting that is stapled to the sole plates. Tapcon screws and various brackets have also been used to help anchor everything down so the tubing does not float up. To the left you can see in the bathroom where the tubing goes through the subfloor to connect with the manifold in the basement.

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The curbless walk-in L-shaped shower. This will get troweled to a semi-rough surface to avoid slipping in the shower (sponge finish?). It will flow under and up against the granite walls and slope down to the drain at the end of the ell (not shown).

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The water closet.

Addition Update, Day 434 (Ouch!)

As I said in an earlier post, we got delayed in our construction over the summer. We got a six-month extension on our building permit, so mid-December is our new target for completion. Still lots to do, but now that the hot weather has broken I am able to get more done. My #1 priority is to get the heat tubing in place so we can schedule the final concrete pour(s). (#2 priority is to get the rooftop solar collection tubes up.)

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Here is the 1000′ roll of 5/8″ Uponor AquaPEX tublng I am putting down. The make-shift support of sawhorses, pipe clamp, and 4″ PVC pipe is working OK, though at first it took two people to unreel since the roll weighed in at 86 lbs.

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The first step was to put rosin paper up to protect the painted walls from concrete splash when the final pour is done. Next was stretching out poultry netting that I will attach the tubing to with zip ties — not really sure about this method but I read about on the Internet so it has to work well, right? Right?? I started with the trickiest of the three 300′ tubing loops, the one under the loft. Among other challenges was the fact that we had to thread the loop through the wall between the bedroom and galley kitchen.

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It took 4 days but the first heating loop is now complete. (FYI, I HIGHLY recommend that you not wait until you are in your late 50’s before undertaking something like this!) The only hitch was that I had miscalculated the layout and end up with some left-over footage that I had to get a little creative with around the bedroom closets. (Besides from the one time I kinked the tubing, but that is exactly why I chose PEX-a rather than -b or -c: you can fix a kink with a heat gun or hair dryer).

Addition Solar Heat Plan

The underfloor hydronic heat in the addition will consist of 3 zones with 4 loops total: basement 1-loop zone, great room 2-loop zone, and under-loft 1-loop zone. Each loop is 300′ 5/8″ PEXa tubing. The expectation is that the great room zone will the most active. The intention is to run each loop at 1.75 gpm, 90°F water in, 75°F out, which should produce 13K BTU/Hr/loop. So the system should produce 26K BTU/hr in “normal” great-room only mode, with an additional 13K each available in the under-loft area and in the basement.

After much research, I have decided to go with this 800 Liter Solar Water Heater System from Duda Diesel. We will be adding the Turn-Key option and upgrading to Freeze Protection tubes so the collectors can handle routine temps below 14°F (which, based on this past winter, I would have to say that we get). The choice between evacuated tube and traditional flat-plate solar collectors was difficult. The reasons why I chose tubes include: lower weight and individual components for easier rooftop installation (we do not have enough non-floodplain sunny areas for ground-based collectors); space between the tubes provides a lower wind resistance; purportedly better performance on cold and/or cloudy days. My concerns are mainly related to the fact that because the outside of the tubes stay cool any frost or snow can take longer to melt than with flat plates. Oh well, a grand experiment awaits!

The heating is a open direct system, with a 211 gallon solar storage tank supplying the underfloor hydronic heat, as well as preheating the water for a standard domestic hot water heater. The 211-gallon solar tank has a built-in heat exchange coil for rooftop solar collectors and an electric heating element for backup. It is not at all certain whether the electric backup, combined with the large thermal mass of our insulated suspended concrete slab floor will be sufficient to keep us warm during extended bad winter weather (but I am quite confident that we will remain at most chilly, not frozen!). Our backup plans include the fact that we still have wood stoves in the old house (our only heat for 17 winters.)

The solar collection side is a closed-loop system with a glycol mixture to prevent freezing. The collectors will mounted on the addition’s east-facing 5/12 pitched (22.62°) metal roof. They will face 11° east of south (the orientation of the house itself) and be tilted up at a 45° angle.

Click on any of the images below to see a larger version:

Solar_heat_schematic

Schematic of the hot water and heating system [Updated 2015-07-22].

RooftopSolarConfig

Location of the rooftop solar collectors. I hope that placing them close to the addition gable end will minimize blocking snow build-up.

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Solar heating schematic from the east. Total heat tube (supply plus return) is about 150′.

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Solar heating schematic from the north.

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The two-zone, three-loop main floor underfloor heat tubes. I need to re-do the loops to put a couple in the bow window floor area. (Our original plans called for a window seat in that area.)

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The underfloor heat tubes in the basement. Placing all the equipment in the mechanical room on the right will be tricky. There are two water tanks, two expansion tanks, and two sets of controllers. Plus I want to plan for a battery bank for future PV solar electric, and the bank will go into a vented box (I have a 3″ PVC conduit in place for that.)

Underfloor Heat Components [already purchased unless noted otherwise]

Polystyrene, Rebar, and Concrete

The main floor of our new addition is a suspended concrete slab (i.e., a slab that is not in direct contact with the ground.) We are using the LiteDeck ICF system for this slab.

LiteDeckBase

The LiteDeck system starts with a base layer of 6″ thick expanded polystyrene (EPS) with imbedded steel C channels (both for strength and to provide a way to screw on the basement drywall ceiling). It is shaped with a beam pocket 6″ W x 4″ H every 2′.

LiteDeckTopHat

Then foam “top hats” (4″thick in our case) are added to deepen the integrated concrete beams to 8″ H x 6″ W.

LiteDeckRebar

Next is the rebar. Lots and lots of rebar: Two ¾” pieces along the bottom of each beam, two ½” pieces along the top, ½” U-shaped cross pieces to help hold the length-wise bars in place, topped with a 2′ x 2′ grid of 1/2″ to stiffen the slab.

LiteDeckReady

Ready for concrete. The rebar is all wired together as a unit. The foam pedestals are for running plumbing and electric through the slab. You can also see the sole plate at the edges – the outside band is temporary bracing. The wooden box-like protrusion on the left is the where the basement stairway will go, the one on the right is for our dumbwaiter.

MainFloorFirstPour

The result (as poured yesterday.) The slab is around 4½” thick. At the top is the vestibule, a 3-season unheated room that also serves as an airlock for the addition entryway. To the right is the cantilevered floor of the bow window.

As I type this the plumbers are here to run a new well pipe through the previously-installed conduit that runs through the foundation. Once inside, it is going to temporarily run through the dumbwaiter window and reattach to the existing house plumbing. Later, we are going to relocate all the plumbing mechanical (pressure tank, de-acidifier, water heater) into the addition’s basement mechanical room. But for now, this will keep the pipe from freezing this winter and allow us to finish back-filling around the north end of the new foundation where the well is.

Next week, the exterior wall framing should begin. The bottom of the wall will be triple-plated so that when the exterior shell, including roof, is in place we can pour the final 4″ of concrete for the final floor. Before that happens, though, I will be running the heat tubing that will end up embedded just above the middle of the 9½” thick floor slab.