Barra Box Results -- With Change Package A


Change package A included these new items and changes:


- Add a backdraft damper mounted in the intake of collector inlet duct just below bottle shelf.


- Add insulation to east, west, and north walls (not done yet)  (1.5 inch polyiso, non-relfective). (now done Jan 19)


- Add more bottles to fill up the bottle shelf (now 3 rows of 18 2 litre bottles).


- Remove the external insulation panel covering the top 7 inches of the collector glazing, and change to the "V" box arrangement inside the collector (see below).


- Add support for the screen absorber top and bottom to allow the screen to be fastened better and to position it more precisely.


- Add support along the top of glazing and a vertical support in the middle of the glazing to keep it from bowing inward and to allow better sealing.


- Add temp sensors to first and last row of bottles rather than just the middle row.


- Add a port on side of collector and light inside collector to allow the backdraft damper to be observed, add the duct air velocity to be read through the port on the side.


- Add a seal strip around the top of the box to provide a flat surface for the lid to sit on.


- Add motor on/off logger to the fan to allow fan on time to be logged.


- disconnect the bottle temperature thermal snap switch as a fan control --fan is now controlled only by room temp.


- Generally improve the sealing for air leaks all around.


- Sprayed some more black paint on the absorber.


- Replaced the "room" thermostat, which was not working (Jan 19)



Some Discoveries on Opening the Box to Install the Change

Many of the bottles had leaked some of their fluid out.  The ones with plain water were OK, but most of the ones with Cola, Sparkling Water, and Tonic Water had leaked -- some quite a bit.


It appears that all the leakage was around the bottle cap, and not due to a failure of the bottle itself. 

Some of the bottles that had pushed out some of their fluid.  Also tend to bulge the bottoms out.


I refilled all the bottles that were not plain water and reused them.

Now have 3 rows of 18 bottles each.



Thermometer at top of collector (just below bottle shelf) did not fair so well.

The tube was lying broken at the bottom.



Results for First 3 Days After Change Package A Changes

The two plots below show the results for the first 3 days after putting in the Change Package A changes.


The one that is marked just "Temp F" is the ambient outside temperature.


Bottles South is the first row of bottles, Bottles North is the last row of bottles.


The "Col In" is now up near the collector inlet duct entrance -- just down stream of the back draft damper.



The added outside insulation was NOT on yet for these plots -- I just added it today (Jan 19).  So, this is same insulation levels as the original box.


The fan was not hooked up for these plots -- the thermostat on the fan was not working, so I disconnected the fan altogether.  I replaced the thermostat today (Jan 19), and plugged it in, but see note about the fan below.


Note on fan:  When I checked the fan after putting the new thermostat in, found it was blowing air up from room into bottle area.  At first I thought this to be a mistake, but after thinking about it a minute, decided to leave it that way -- logic being that if it blows air from bottle area into the room, it will also blow air through the backdraft damper (since this is the normal flow direction) -- at night this will result in room air blowing past the glazing and then back into the bottle area.  With fan blowing air from room to bottle area, it seems like it may close the backdraft damper (I'll check on this when the fan starts running).  And, it should also circulate room air past the bottles and back into the room via the slot at the north end of the bottle shelf?








Closer view of the middle day from plot above.


I've had a chance to watch the back draft damper both during the collection period and at night, and it seems to be doing the job.  It opens to about 45 degrees in full sun, and the Vane Meter reads about 50 fpm.   At night it sucks tight against the hardware cloth backing.  I'm sure there is still a bit of leakage around the edges, but I think it seals pretty well.




Changes to Collector and Glazing



Added a wood bar about 7 inches down from top of glazing to support the new "V" box at top of collector, and a vertical glazing support in the middle (the EMT conduit).  

These are both to support the new "V" box and to keep the glazing from bowing in so much.


Added a wood strip along the bottom of the absorber (clamps hold it while foam glue dries).  This is to have something solid to staple the black screen absorber to.



This shows the new "V" arrangement at top of collector -- Nick's idea to get some useful heat out of the top few inches of collector without losing a lot of heat from the bottle shelf area at night.



Single layer of screen absorber stapled in place between the new wood strip at bottom of absorber and the new wood strip at bottom of the new "V" near top of collector.

The screen was later stapled under the top wood strip so that at the top of the screen, it is about half an inch from the glazing.  So, flow path is: air enters bottom of collector between the glazing and the screen.   Air rises up through the screen, and exits the collector at the top behind the new "V" board and then North into the bottle shelf.




New Insulation on Collector Inlet Duct

Added new insulation boards on the south and north sides of the north wall of the inlet duct.  There are two boards, each is 1 inch polyiso -- non-reflective. 

Also sealed all the floor to wall and wall to wall joints with Great Stuff on inside of box.


Backdraft Damper



This is the framework for that holds the backdraft damper.  The top part shows the half inch hardware cloth used to back up the poly film.

Bottom part is getting the poly film.

This backdraft damper frame sits on top of the inlet  duct north wall, and is oriented to allow north to south flow, but stop south to north flow.


The backdraft damper does not seal perfectly against backdrafts -- there are very small gaps and cracks around the edges in places, but it looks pretty good to me.  It gets pulled against the hardware cloth backup as soon as the sun goes off the collector.


Backdraft damper installed on top of the inlet duct wall before the bottle shelf is installed over it. 

Note the Dwyer Van Meter installed near the middle.

So, air flow under the bottle shelf northward through the poly film backdraft damper, and then down the inlet duct,  then under the absorber from north to south, up the south side of the absorber.  When it reaches the top of the absorber, it flow north over on top of the botttle shelf through the bottles.




Collector in operation.  Backdraft damper poly film blown out by entering air.  Vane meter reading just under 50 fpm -- probably would be right at 50 if the vane meter were level.

This picture is taken through the hole in the side of the box shown just below.

Hole cut in side of collector to allow the performance of the backdraft damper to be observed.

A light is mounted just below the hole and inside the collector to light the damper and the vane meter.

The hold is plugged with the hole saw cutout when not taking pictures.



3 rows of 18 2 liter pop bottles installed on top the bottle shelf.

Also new wood seal strip all the way around the top of the walls and glazing to make a flatter surface for lid to sit on -- these are sealed/glued to top of walls with Great Stuff.






Bottle temp sensors taped to south row (at black tape), and to north row.  Sensor is positioned at the side of bottle where it contacts the next bottle.

Fan inlet is just visible to left.  

The snap disk thermometer switch to  left in foreground is not currently used, but could be used to keep the fan from turning on when the bottles cool below some set temperature.


For the initial setup, the fan is unplugged just to give the bottles some time to warm up.

This shows the thermostat in the middle of the "living room".  It is set to about 65F. 

The logger sensor that records roomt temp is the black taped gadget on the grey wire.

Both are about half way down into the living room.

The collector inlet duct with backdraft damper is visible at the top of picture.

The fan outlet is also visible.


The small crack between the inlet duct wall and the floor is calked from the other side.



Looking up into the fan outlet with the motor on/off logger mounted on the end of the fan motor.




Added Insulation

On Jan 19, added 1.5 inches of polyiso (non reflective) over the north, east, and west walls. 

So insulation levels now are:

- Lid -- 2 inches relfective polyiso + 2 inches non reflective polyiso

- east, west, and north walls -- 2 inch reflecticve polyiso + 1.5 inch non reflective polyiso

- bottom -- 2 inch non-reflective polyiso + 2 inches extruded polystyrene


Collector inlet duct has 1 inch polyiso + OSB + 1 inch polyiso


New Room Thermostat

The thermostat shown in the picture above did not work.  Since it was running the fan all the time, I just unplugged the fan in the interium.

I replaced it with an electric baseboard style thermostat.  As of late Jan 19, its running with the fan activated and the new thermostat.


Gary January 15, 2010