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An Allentown house - Page 3

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Posted by nicksanspam on October 10, 2007, 7:18 am
 

We could lower the sdamper with an SPDT thermostat and 2 power darlingtons
when the sunspace is warmer than 80 F, like this, viewed in a fixed font:

              sw* (open if ss<80 F)    
+12 -------|----------------------------
       |                                |
       |      sw         1K             |
        ---X------------www---|         |
                    |                   |
           limit    - open when         - open when
           switches | fully up          | fully down
                    |                   |
                    |       down        |
                    |       ---->       |
                    |------sdamper------|
                    |                   |
                    |                   |----------------www---|
                    |                   |            |
                   /             1K    / c           |
        -----www--|         sw --www--|p    TIP120   |
       |           \                   \ e           |
       |            |                   |            |
       |            -                   -            |
       |                                             |
        ---------------------------------------------

And lower the adamper whenever the house needs heat, with a setback thermostat
(the setback stores overnight heat in the house thermal mass):

          
+12 ------------------------------------
                    |                   |        
                   /             1K    / e      
       hw* --www--|         hw --www--|n    TIP125
                   \                   \ c      
                    |                   |      
                    |                   |
                    - open when         - open when
                    | fully up          | fully down
                    |                   |
                    |       down        |
                    |       ---->       |
                    |------adamper------|
                    |                   |
                    |  hw               |  hw*
                    |------www---|      |----------------www---|
                    |                   |            |
                   /             1K    / c           |
        -----www--|    +12 ---X--www--|p    TIP120   |
       |           \          close    \ e           |
       |            |         for heat  |            |
       |            -                   -            |
       |                                             |
        ---------------------------------------------

And run the 2 12V fans when the house needs heat or (the tank needs heat
and the radiator is warmer than the tank) using a differential thermostat:
                                  
hw --------------------------------------->|--------- fans in series---|
                            open if             |
                            tank > 140F         |
 -------------   +12 --X--------|--------->|-------- f
|differential |-------uuu---         |
|             |  120V relay |        |--- tank
|  thermostat |-------------         w
 -------------                       w
                                     w
                                     |
                                     -

The pump would run with the fans, except when the sunspace is warm and
tank water is not being heated, with a NOR gate and a 12V relay:

                    
        f ---www------------  120V
                       |    |
                      /     u  |
      hw* ---www-----|p     u  X
                  |   \ e   u  |
     tank ---www--     |    |   --- pump
                       -    -

As an alternative, we could control the system with a $9 Eway PC and
a single motorized damper and 5 one-wire DS18B20 temperature probes,
which would allow automatic passive room heating with less damper
motion and lower-power pumping after the pipes are full.

Nick


Posted by nicksanspam on October 15, 2007, 12:31 pm
 
If outdoor air varies from 60 to 80 F on an average July day and the house
gains 34K Btu/day from 300 kWh of indoor electrical use plus 5K Btu of DHW
storage tank loss, with 6 hours per day of night ventilation, we need to
store 18h/24hx39K = 29K of coolth. If its thermal mass C warms from 65 F
in the morning to 75 by afternoon, (75-65)C = 29K makes C = 2.9K Btu/F.

A house with an inherent thermal mass of say, 2K Btu/F (1 Btu/F per board
foot of drywall, etc.), might include some basement mass for cooling, eg
900/55 = 16 4"x10' horizontal thinwall endcapped PVC water pipes tucked up
between first floor joists with a 3/4" hole on top and a #3 rubber stopper.
With more pipes or some uninsulated basement walls, we could store coolth
for a few warm days in a row.


In summertime, we could close the lower adamper and let outdoor air enter
the basement via a one-way window convection damper and exit via a summer
sunspace vent, like this, viewed in a fixed font:

 ------------------------------------------
|          . motor    r    motor .      .  
|          . <-->     a     <--> .      . ==>   (raise the upper damper to  
|          .         fd          .      .        stop natural airflow when
|          .     ==> ai  ==>     .  2'  |        the house temp drops
|          .         na          .      |        to 65 F)
|          .         st          .  s   |    
|          .          o    2'    .  u   |    
|          |--adamper-r--sdamper-|  n   |     s
|          |                     |  s   |     o    
|          |                     |  p   | 20' u  thermosyphoning night air
|          |      2K Btu/F       |  a   |     t  cools house and basement
|          |         house       |  c   |     t
|          |          mass       |  e   |     h
|          a                     .s     |
|          d                     .d     |      
|          a                     .a     |      
|          m                     .m     |    
|    ^     p                     .p     .  
|    |     e                     .e     .
|    |     r                     .r     .
|...........-------------.......---------------------
|             900 Btu/F |        |
| basement .   basement |        |
|   window         mass |        |
|   damper .            |        |
|                       |        |
| .  .  .  .                     |
|                                |
|                                |
 --------------------------------    

During the day, we could run the radiator fans to cool the house with
basement air using a room temp thermostat and an occupancy sensor:

 ------------------------------------------
|          . motor    r    motor s      .  
|          . <-->     a     <--> d      . ==>
|          .         fd          a      .  
|          .    <==  ai <==      m  2'  |    
|          .         na          p      |    
|          .         st          e  s   |    
|          .          o    2'    r  u   |    
|          |--adamper-r--.......-|  n   |     s
|          |                     |  s   |     o
|          |                     |  p   | 20' u  basement air cools house
|          |      2K Btu/F       |  a   |     t  during the day
|          |         house       |  c   |     t
|          |          mass       |  e   |     h
|          a                     .s     |
|          d                     .d     |      
|          a                     .a ^   |      
|          m                     .m |   |    
|    |     p                ^    .p |   .  
|    |     e                |    .e     . <== outdoor air cools sunspace
|    v     r                |    .r     .
|...........-------------.......---------------------
|             900 Btu/F |        |
| basement .   basement |        |
|   window         mass |        |
|   damper .            |        |
|                       |        |
| .  .  .  .            |        |
|              ==>               |
|                                |
 --------------------------------    

In 6 hours, 2 2'x3' vents with a 20' height difference and a 70-65 F avg
temp diff can move 6hx16.6x2'x3'sqrt(20')(70-65)^1.5 = 30K Btu/day.

Nick


Posted by Jeff on September 24, 2007, 4:50 pm
 nicksanspam@ece.villanova.edu wrote:

   I think so. That's on the south facing wall of the house. It has an
additional 16" slanted top.

   Different locations. The water collectors will be roof mounted south
facing at ~ 40 degrees. I think that's not bad for Atlanta.

   I have a shed at the south end of the property that will be mostly in
  open sun in the winter. There's maybe a 150 SF of south facing roof
there. If I solkoted (selective coating) galvanized roofing would I get
enough temperature rise as an unglazed trickle collector? I'm thinking
this would fall short, but am unsure. I think perhaps CPVC
tarred/siliconed in the V's of the roofing and some semi serpentine
plumbing may put me in the 100F water temp range that could be usefull.
It's not something I can calculate. Certainly would be much less on a
windy day!

   I think this project will wait a year. And get more costly...


Posted by nicksanspam on September 25, 2007, 2:26 pm
 

I suspect the coating wouldn't keep its effectiveness long outdoors.

Nick


Posted by Jeff on September 25, 2007, 6:13 pm
 nicksanspam@ece.villanova.edu wrote:

   I ran across this oldy but goody article of yours:

<URL: http://www.ece.villanova.edu/~nick/Solar_Heat.pdf  />

  What's the verdict on trickle collectors, I haven't heard you talk
about them for a while?

  It seems the big disadvantage is the need for glass as glazing.

   Cheers,
Jeff



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