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Posted by nicksanspam on September 24, 2007, 4:16 pm
 
PA Renewable Energy Festival 9/22/07

100% Solar House and Water Heating with Sunspaces, by Nick Pine

It is commonly believed that houses can't be more than about 50% solar heated.
This is true of direct gain "mass and glass" passive solar houses, since
the windows lose lots of heat at night and on cloudy days and we have to live
inside the "heat battery," so the mass can't be hot on an average day, so
it can't store much heat.

If cloudy days are like coin flips, a house that can store heat for 1 day can
be at most 50% solar heated; 2 days make 75% possible, 3 make 88% possible;
4 allow 94%, and 5 allow 97%. More than 5 becomes uneconomical. Designing
for 100% solar heating begins with the local weather...

National Renewable Energy Laboratory (NREL) data say December is
the worst-case month for solar heating in Allentown, when 800 Btu/ft^2
of sun (300 diffuse) falls on a south wall on an average 31.8 F day
with a 24.4 and 39.2 daily max and min.

We can use basic high-school physics (eg "Ohm's law for heatflow," like
Ohm's law with different units) and algebra to determine how much insulation
the house needs, based on constant internal energy gains and a easily-built
heat storage tank: if the house is 65 F on average indoors (eg 70 F for
12 hours per day and 60 for the other 12) and a frugal 300 kWh/mo of indoor
electrical use (vs an 800 kWh/mo US national average) provides 34K Btu
of heat on an average day and a 4'x8'x3'-tall plywood heat storage tank
on the ground (with a single 10'x14' piece of EPDM rubber roofing material
folded up like a Chinese take-out box as a liner) containing 4x8x3x62.33
= 5984 pounds of 140 F water warms the house using an 800 Btu/h-F radiator
for 5 cloudy days until it cools to Tmin and the house thermal conductance
is G Btu/h-F and we keep it 70 F on a 24.4 F morning, (Tmin-70)800
= (70-24.4)G makes Tmin = 70+0.057G.

On an average day, we need 24(65-31.8)G-34K = 796.8G-34K Btu of heat energy.
If (140-Tmin)5984 = (140-(70+0.057G))5984 Btu = 5d(796.8-34K), G = 136 max,
and Tmin = 78 F, and the house needs 74.4K Btu/day of non-electrical heat.

A 1024 ft^2 house with a 640 ft^2 loft might look like this, viewed in a
fixed font:

                    .
            .       .
    .               .
    .               . 12'
  8'.               .
    .    24'        . south -->
    . . . . . .     .
    .               .
  8'.         .     . 8'
    .               .
    .         .     .
...........................
           32'

    . . . . . . . . .
    .         .     .
    .         .     .
    .         .     .
    .   top   .     .
    .         .     . 32'
    .  view   .     .
    .         .     .
    .         .     .
    .         .     .
    . . . . . . . . .


If made entirely of Structural Insulated Panels (18 SIPs?) with R-value Rv
and 1024 ft^2 of ceiling and 2304 ft^2 of walls and no air leaks, G = 136
= 3328ft^2/Rv makes Rv = 24 ft^2-F-h/Btu min; 8" R32 SIPs make G = 104.
With good airsealing and 32 cfm of leaks, we might have G = 136.

With 136 ft^2 of R30 walls and G = 136/30 = 4.5 Btu/h-F, the tank would
supply 24h(140-65)4.5 = 8K Btu of house heat on an average day, leaving
a need for 74.4K-8K = 66.4K Btu/day of solar air heat (line 150 in the calc
below.) Sunspace air keeps the house 70 F during collection time and stores
overnight heat in the house mass (line 340), which cools to 60 at dawn.

If 500 Btu/ft^2 of 250 Btu/ft^2 full sun arrives in 500/250 = 2 hours on
a 6-hour collection day and 300/(6h-2h) = 75 Btu/h-ft^2 arrives in the other
4 hours, we can model A ft^2 of $/ft^2 Thermaglas Plus U0.58 twinwall
polycarbonate "solar siding" with 80% solar transmission over a 1 foot
air gap over a dark south wall like this, viewed in a fixed font:

  0.8x250AS = 200A Btu/h                1/(0.58A)
        ---                         -------www---------- TSF
   |---|-->|---------- TSF         |
        ---     |         -       ---  35+200A/(0.58A) = 380 F
                |         -        -
     1/(0.58A)  |         -        |
35 F----www-----                   -

TSF is a Thevenin equivalent (no load, stagnation) sunspace air temp in
full sun. With A = 192 ft^2 (line 170) and a 140 F auto radiator and its 2
30 watt 1000 cfm 12 V fans to heat tank water:

          RS               TAF    Q Btu/h
         1/111    1/1000    |       ---
   -------www-------www-----*------|-->|---- 65 F
  |           -->           |       ---
 --- 380 F      I         | |
  -              4K Btu/h | | 1/800  140 F |
  |                       v  --www---------| |--|
  -                                        |

We can collect 8K Btu/h of tank heat in 2 hours at sunspace air temp TAF
= 140 + 4K/800 = 145 F. At the same time, we can collect Q Btu/h of warm
sunspace air. With RSER = RS + 1/1000 = 1/100 and I = (380-145)/RSER
= 23.5K Btu/h (6.9 kW at $5K, for PV fans :-), Q = I-4K = 19.5K Btu/h.

In diffuse sun, we have:

  0.8x75x192 = 11.5K Btu/h                1/111
        ---                         -------www-------- TSD
   |---|-->|---------- TSD         |
        ---     |         -        | 35+60/0.58 = 138 F
                |         -       ---
      1/0.58    |         -        -
35 F----www-----                   |
                                   -
And:
                TAD
         1/111  |    1/1000
   -------www---------www----- 65 F
  |           ---->
 ---  138 F     I
  -
  |
  -

I = (138-65)/RSER = 7300 Btu/h. We collected 2Q = 39K Btu of the 66.4K/day
air heat in full sun. We can collect the rest in (66.4K-39K)/I = HDIFF
< 4 hours, so 4 4'x12' sheets of twinwall suffice. We could verify this
with a simple simulation using NREL's Allentown TMY2 weather file with
measured hourly weather data for a Typical Meteorological Year.

20 TAVG1.8'24-hour Dec temp in Allentown (F)
30 TMAX9.2'average daily max (F)
40 TDAY=(TMAX+TAVG)/2'average daytime temp (F)
50 GSUN0'south wall global sun (Btu/ft^2-day)
60 DSUN00'south wall diffuse sun (")
70 FSUN=GSUN-DSUN'south wall full sun (")
80 HSUN=FSUN/250'full sun hours
90 HDAY=6'daytime hours
100 GHOUSE6'house conductance (Btu/h-F)
110 HHOUSE$*(65-TAVG)*GHOUSE'average day house heat (Btu)
120 UELEC00'indoor electrical use (kWh/mo)
130 HELEC412*UELEC/30'electrical heat gain (Btu/day)
140 HTANK00'tank heat (Btu/day)
150 ESSA=HHOUSE-HELEC-HTANK'sunspace air energy (Btu/day)
160 PRINT HHOUSE,HELEC,HTANK,ESSA
170 A=4*4*12'sunspace glazing area (ft^2)
180 RS=1/(.58*A)'glazing resistance (F-h/Btu)
190 ISF=.8*250*A'full sunspace heatflow (Btu/h)
200 TSF=TDAY+ISF*RS'full sunspace equivalent temp (F)
210 CFM00'fan cfm
220 RSER=RS+1/CFM'sunspace series resistance
230 GRAD0'radiator conductance (Btu/h-F)
240 TAF0+HTANK/GRAD/HSUN'full sunspace air temp (F)
250 PRINT TSF,TAF,HSUN
260 FSSA=HSUN*(TSF-TAF)/RSER-HTANK'full sunspace air heating (Btu)
270 ISD=.8*A*DSUN/(HDAY-HSUN)'diff sunspace heatflow (Btu/h)
280 TSD=TDAY+ISD*RS'diffuse sunspace equivalent temp (F)
290 ICAP=(TSD-65)/RSER'house cap heatflow (Btu/h)
300 TAD=TSD-ICAP*RS'diff sunspace air temp (F)
310 HDIFF=(ESSA-FSSA)/ICAP'house heating hours)
320 PRINT TSD,TAD,HDIFF
330 HCOLL=HSUN+HDIFF'solar collection hours
340 ESTOR=ESSA-HCOLL*((70-TDAY)*GHOUSE-HTANK/24)'overnight heat (Btu)
350 HCAP=ESTOR/(70-60)'house heat capacity needed (Btu/F)
360 PRINT A,HCAP,HCOLL,HDAY

GHOUSE        HELEC         HTANK         ESSA
Avg day       electrical    tank heat     Warm air
heat (Btu)    heat (Btu)    (Btu)         heat (Btu)
108364.8      34120         8000          66244.81

TSF           TAF           HSUN
Full sun      Sunspace      Full sun
eq temp (F)   temp (F)      hours
380.3276      145           2

TSD           TAD           HDIFF
Diff sun      Sunspace      House heat
eq temp (F)   air temp (F)  hours
138.9483      72.40973      3.65525

A             HCAP          HCOLL         HDAY
Glazing       House mass    Collection    daytime
area (ft^2)   (Btu/F)       hours         hours
192           4159.546      5.655251      6

Nathan ran a $5 '95 Mitsubishi radiator on a 20 watt PV panel during his
Festival talk, with the 2 fans in series. In Melbourne, he measured a Mazda
radiator conductance of 972 W/C (1842 Btu/h-F.) The radiator and its fan
could be at the top of a vertical duct that returns sunspace air to the lower
sunspace without mixing with room air. On cloudy days, we pump water up
through the radiator to warm the house. A $0 1"x300' 13-gallon pressurized
plastic pipe coil heat exchanger in the tank could heat water for showers,
with the help of a greywater heat exchanger, eg a plastic 55 gallon drum
with a filter to drip greywater through a 100' black plastic PE pipe with
a smaller 100' PE pipe inside it that thermosyphons pressurized warm water
up into a tank water heater, with a way to backflush the greywater path
from time to time. A non-toxic 0.5% sodium silicate solution (eg "ACI-100"
from D. W. Davies) could prevent corrosion of the aluminum radiator core.

Air might flow as in the diagram below, conceptually, with a room air fan
and an upper motorized damper (the sdamper in the figure below) hinged at
the bottom (use Honeywell's 6161B1000 $0 2W damper actuator or a $5 DC
gearmotor from Grainger or a windshield wiper motor with limit switches or
a 12V damper from an auto heater or a cordless drill) that opens inwards
up to 90 degrees (moving counterclockwise) to block room airflow in
the horizontal position:

                 top        2'                 top
     ----------------------------          -----------
   a.         r    motor s.      |        |           |
   d.        fa     <--> d.      |        |  adamper  |
   a.         d          a.      |        |           |
   m.    <== ai          m. 2'   |        |  sdamper  | 2'
   p.         a          p.      |        |           |
   e.        nt          e.      |        |           |
   r.         o          r.  s   |        |           |
    |         r-.........-|  u   |        |-----------| west
    |              4'     |  n   |        |           |
    |                     |  s   |        |           |
    |              ^      |  p   | 20'    |           |
    |              |      |  a   |        |           |
    |               room  |  c   | s      |           |
    |                air  |  e   | o      |           |
    |                     |      | u      |           |
   r.a                    .s     | t      |           |
   o.d room      sunspace .d ^   | h      |           |
   o.a  air           air .a |   |        |  adamper  |
   m.m  ==>           ==> .m     |        |           |
   f.p                    .p     |        |  sdamper  |
   a.e                    .e     |        |           |
   n.r                    .r     |        |           |
     ----------------------------          -----------
                                                12'
     ----------------------------     Drawing not to scale.
   a|a        r          s|s     |
   d|d       fa          d|d     |
   a|a        d          a|a     |
   m|m   <== ai  top <== m|m 4'  | 12' south
   p|p        a          p|p     |
   e|e       nt          e|e     |
   r|r        o          r|r     |
     ---------r------------------
                 west
Modes:

1. To heat the tank, pull sunspace air through the radiator with its fan
and return it to the sunspace below, with the motorized sdamper horizontal.
A lower one-way lightweight plastic film convection sdamper opens (to
the right) over a vertical hardware cloth grate when the fan runs and
prevents reverse sunspace thermosyphoning at night.

2. To heat the house, push room air into the lower part of the duct with
the room fan (eg a $0 Lasko 2155A) and pull it through the radiator and
out to the room via the upper adamper. The upper and lower adampers should
be sloped vs vertical, and heavy enough to stop room air thermosyphoning
up through the vertical duct when room heat is not required.

3. To do both, open the damper halfway, or give house heating priority.

Notes:

1. For more exact room temp control and less mass, add mass to the upper
8'x32' of ceiling, with a slow ceiling fan and a room thermostat to keep
the house exactly 70 F when occupied and 60 when it's unoccupied. An open
wintertime door in place of the upper adamper can let sunspace air flow
into the room to heat the ceiling and return to the sunspace without mixing
with room air... 120 F ceiling mass can store 7 times more heat than 70 F
mass, with a shiny surface beneath to avoid room overheating by radiation.

2. My tribologist brother Dave says auto radiator electric fan bearings
last 3K-4K hours (some last 7K hours) when tested at 225 F. Life doubles
with every 10 C decrease, so they might last 4000x2^((225-145)/1.8) = 87K
hours at 145 (i.e. 10 years of continuous operation :-)

Nick


Posted by Sundug on September 25, 2007, 8:54 pm
 
On Sep 24, 11:16 am, nicksans...@ece.villanova.edu wrote:

Direct gain passive solar, properly designed can provide much more
than 50% of heating needs, I`ve been living in a direct gain home that
solar provides 90% of heaqting needs. Doug

91 award winning solar passive homes-

http://www.builditsolar.com/Projects/SolarHomes/91HomesBook/SolPasPlans91.h=
tm


How to design and build a passive solar home that is energy efficient,
saves money, is easy on the planet, and is GREAT to live in.-

http://www.builditsolar.com/Projects/SolarHomes/solarhomes.htm

"I Did It" Sites and Stories
http://www.builditsolar.com/Projects/SolarHomes/ididitps.htm

In Colorado-
http://groups.google.com/group/sci.environment/browse_frm/thread/bc4c421026=
4c805d/a898d447f9086fe8?lnk=st&q=Passive+solar+home&rnum=8&hl=en#a8=
98d447f9086fe8

"I love having a passive-solar house," she said. "It definitely makes
a
difference in the winter. "On cold, sunny days in the winter, the
furnace
doesn't even come on."


Albritton's house, like all of the houses in Solar Ridge, is angled to
harness
the energy of the sun in the winter. There are large overhangs
shielding the
floor-to-ceiling windows on the south side of the house from the
summer sun. In
the colder seasons, when the sun travels in a lower arc across the
sky, the
windows are in an ideal position to harness the sun's heat.

Robald said that passive solar is enough to heat his 2,200-square-foot
house on
the majority of winter days, with the furnace only coming on at
night.

In a 4,000-square-foot home Cox built in Solar Ridge, the highest
natural-gas
bill was $4.72 for the period from mid-December to mid-January. The
next
month, the bill dropped to $5.08.

Passive solar is still the "cornerstone of energy-efficient,
environmentally
friendly homes," Schroeder said.


http://www.earthtoys.com/emagazine.php?issue_number=07.02.01&article=ec=
ological

Licensed master mechanic Gemma McKee says her new passive solar home
near Branson, Missouri, "sticks out like a sore thumb." In other
words, there hasn't been a glut of energy efficient construction going
on in her neighborhood. McKee's home is 3,570 square feet, one story
tall and designed to include a full range of creature comforts and
unusual design aesthetics. She can also heat and cool the whole space
for under $0 a month.
---------------------------------------------------------------------------=
-----
http://www.eere.energy.gov/consumer/your_home/designing_remodeling/index.cf=
m/mytopic=10290

"Passive solar homes range from those heated almost entirely by the
sun to those with south-facing windows that provide some fraction of
the heating load.
The amount of passive solar (sometimes called the passive solar
fraction) depends on the area of glazing and the amount of thermal
mass. The glazing area determines how much solar heat can be
collected. And the amount of thermal mass determines how much of that
heat can be stored. It is possible to undersize the thermal mass,
which results in the house overheating. There is a diminishing return
on oversizing thermal mass, but excess mass will not hurt the
performance. The ideal ratio of thermal mass to glazing varies by
climate.
----------------------------------------------
The Hodges Passive Solar Home in Ames, Iowa
http://www.public.iastate.edu/~lhodges/house.htm
The Hodges Residence has proved extremely pleasant to live in, both in
winter and in other months. The direct gain system provides excellent
natural lighting to both levels, even on cloudy days. The temperature
fluctuations in the home are not large, because of the large amount of
thermal storage mass with a large surface area.
--------------------------------------------
http://www.nesea.org/buildings/passive.html

Thermal Mass is any material in the home that absorbs and stores heat.
Concrete, brick, tile and other masonry materials are the most common
choices for thermal mass in a passive solar home, these materials
absorb and release heat slowly and are easily and inexpensively
integrated into the house design. They are most effective when dark
colored and located in direct sunlight. The addition of thermal mass
allows saved solar energy to heat the house at night or on cloudy
days. The combination increases the performance and energy-saving
characteristics of the home, generally for only a modest cost
increase.
---------------------------------
The passive solar home: fed up with high energy bills? Make your house
into a solar collector!

http://findarticles.com/p/articles/mi_m0KWZ/is_4_3/ai_87703742

With the help of technology and experience, passive solar houses today
can enjoy the warmth and comfort of solar heat and still look and feel
just like home. In the our region, passive solar design usually means
using the sun to help heat the house, but it can also refer to passive
cooling strategies. For the purpose of this article, I have limited
what follows to what I consider to be the easiest and most cost-
effective means of passively heating a house: using living space as a
solar collector.


Posted by nicksanspam on September 25, 2007, 11:04 pm
 

Bullshit! :-)

Nick


Posted by nicksanspam on September 29, 2007, 2:04 pm
 
Air might flow as below, with no room air fan, just the 2 radiator fans
in series and an upper motorized sdamper, hinged at the bottom, with
a windshield wiper motor with limit switches that opens inwards up to 90
degrees (moving counterclockwise) to block room airflow in the horizontal
position, like this, viewed in a fixed font:

                 top         2'                top
     ----------------------------          -----------
    |          r   motor s.      |        |           |
    |          a    <--> d.      |        |           |
    |         fd         a.      |        |           |
    |    <==  ai <==     m.  2'  |        |  sdamper  | 2'
    |         na         p.      |        |           |
    |         st         e.      |        |           |
    |          o    2'   r.  s   |        | (sdamper) |
    |          r-........-|  u   |        |-----------|    
    |          |    ^     |  n   | s      |     ^     | cool
    |          |    |     |  s   | o      |     |     | room
    |          | cool room|  p   | u  20' |      ---  | air    east
    |          | air inlet|  a   | t      |           | inlet
    |           ----------|  c   | h      |-----------|
    |                     |  e   |        |           |
    |                     |      |        |           |
    .                     .s     |        |           |
    .            sunspace .d     |        |           |
    .                 air .a ^   |        |           |
    .<== warm room    ==> .m |   |        |  sdamper  |
    .    air outlet       .p |   |        |           |
    .                     .e     |        |           |
    .                     .r     |        |           |
     ----------------------------          -----------

            cool room                          12'
            air inlet
                    |                 Drawing not to scale.
                    v
     ----------------------------  
    |          r   top   s|s     |
    |         fa   view  d|d     |
    |          d         a|a     |
    |    <==  ai <==     m|m 4'  | 12' south
    |          a         p|p     |
    |         nt         e|e     |
    |          o         r|r     |
     ----------r------------------
                  west
Modes:

1. To heat the tank, pull sunspace air through the radiator with its fans
and return it to the sunspace below, with the motorized sdamper horizontal
and Grainger's 4PC93 pump on if the tank is less than 140 F and the sunspace
is warmer than the tank. A lower one-way lightweight vertical plastic film
convection sdamper opens over a hardware cloth grate when the fan runs and
prevents reverse sunspace thermosyphoning at night.

2. To heat the house, pull room air through the radiator and back into
the room via the lower room air grate, with the upper sdamper horizontal
and the pump off if the sunspace is warmer than the room, and the upper
sdamper vertical and the pump on if the sunspace is colder.

3. To do both, alternate modes 1 and 2, moving the damper slowly, with
full action in about 5 minutes at a 1% PWM duty cycle. At full speed,
our '97 Ford Taurus wiper motor opened a 1' damper with a 3" pulley in
about 3 seconds. We put a 10 ohm resistor in series to reduce coasting.

house  tank      sunspace
<70?   <140?  >70?   >tank? | damper  fans  pump  notes
--------------------------------------------------------------------------
0      0      -     -       | up      off   off   default
0      1      1     1       | down    on    on    heat tank
1      0      0     -       | up      on    on    heat house with tank
1      0      1     -       | down    on    off   heat house with sunspace
1      1      1     1       | down    on    on    heat house and tank

The room air temp might be 70 F during the day and 60 at night, with
a setback thermostat. The damper motor circuit might look like this,
with the damper normally down:

+12 --------------------------------------
       |                                  |
       - opens when up,                   - opens when down,
       | to limit travel                  | to limit travel
       |                                  |
       |                                  |
       x close to raise                   - open to raise
       |                                  |
       |               lower              |
       |              <------             |
       |               -----              |
       |--------------|motor|-------------|
       |               -----              |
       |                                  |
       |                                  |
       - open to raise                    x close to raise
       |                                  |
       |                                  |
       |                                  |
   |--------------------------------------
                                                              --
The damper might look like this, in a fixed font:           /    \
                                                          /|motor&|
                                                        /  |pulley|
                                                      /     \    /
                                                    /      |  --  |
     -----------------------------------------------------------------
    |   .                                       /   |
    |   .                                     /    o|
    |   .                                   /       \  
    |   .                                 /         |-
    | r .                               /           |s| upper limit
    |   .                             /            f| | roller leaf
  F |   .                           /              e|s|      switch
    | a .                         /                l|-
    |   .                       /                  t|
    |   .                     /                     |
    | d .                   /                  (up) |
    |   . <==             /                         | <-- sunspace
  A |   .               /                           |          air
    | i .             /                             |
    |   .           /                               | ~2'
    |   .         /                               h |
    | a .       /                                 i |
    |   .     /                                   n |
  N |   .   /                                     g |
    | t .  |               (down)            strape |
    |   . ----------------------------------------  |
    |   .|               1/2" plywood             | |
    | o .|----------------------------------------| |
    |   .|                                        | |
  S |   .|          2" foil-polyiso board         | |
    | r .|                                        | |
    |   .|----------------------------------------| |
    |   .|               1/2" plywood             | |
    |   . ----------------------------------------  |
    |   .                                           |
    |   . ~~~~~~~~~~~felt weatherstripping~o~~~~~~~~|
     ---------------------------------------\---------------------
                        ^                    |s  s|
                        |                     ----  lower limit
                         room air                   roller leaf switch
Nick


Posted by nicksanspam on October 7, 2007, 7:13 pm
 
We might have 2 motorized dampers, fully-open or fully-closed, like this:

     ----------------------------    
    .a motor   r    motor .      |  
    .d <-->    a     <--> .      |
    .a        fd          .      |     heat water with sunspace
    .m   <==  ai <==      .  2'  |      
    .p        na          .      |      
    .e        st          .  s   |    
    .r         o    2'    .  u   |    
    |.......---r--sdamper-|  n   | s
    |   |           ^     |  s   | o
    |   v           |     |  p   | u    
    |               room  |  a   | t  
    |               air   |  c   | t
    |                     |  e   | h
    .                     .s     |
    .            sunspace .d     |      
    .                 air .a ^   |      
    .                 ==> .m |   |    
    .                     .p |   |  
    .                     .e     |
    .                     .r     |
     ----------------------------    

     ----------------------------    
    . motor    r   motor s.      |  
    . <-->     a    <--> d.      |
    .         fd         a.      |     heat house with water
    .    <==  ai <==     m.  2'  |      
    .         na         p.      |      
    .         st         e.  s   |    
    .          o    2'   r.  u   |    
    |adamper---r--.......-|  n   | s
    |               ^     |  s   | o
    |               |     |  p   | u    
    |               room  |  a   | t  
    |               air   |  c   | t
    |                     |  e   | h
    .                     .s     |
    .                     .d     |      
    .                     .a ^   |      
    .==> cool room        .m |   |    
    .    air inlet        .p |   |  
    .                     .p |   |  
    .                     .e     |
    .                     .r     |
     ----------------------------    

     ----------------------------    
    . motor    r    motor .      |  
    . <-->     a     <--> .      |
    .         fd          .      |     heat house and/or water
    .    <==  ai <==      .  2'  |     with sunspace
    .         na          .      |      
    .         st          .  s   |    
    .          o    2'    .  u   |    
    |adamper---r--sdamper-|  n   | s
    |               ^     |  s   | o
    |               |     |  p   | u    
    |               room  |  a   | t  
    |               air   |  c   | t
    |                     |  e   | h
    .                     .s     |
    .            sunspace .d     |      
    .                 air .a ^   |      
    .==> cool room    ==> .m |   |    
    .    air inlet        .p |   |  
    .                     .e     |
    .                     .r     |
     ----------------------------    

with this simple logic:

house tank    sunspace   upper upper
<70?  <140? >70?  >140?| sdamp adamp fans  pump  notes
-------------------------------------------------------------------------
0     0      -    -    | up    up    off   off   default
0     1      -    1    | down  up    on    on    heat tank
1     0      0    -    | up    down  on    on    heat house with tank
1     0      1    -    | down  down  on    off   heat house with sunspace
1     1      1    1    | down  down  on    on    heat house and tank

Nick


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