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Home automation controllers

Discussion in 'Home Power and Microgeneration' started by [email protected], Jun 9, 2007.

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  1. Guest

    Nathan and I have settled on a mini-pc for a smart whole house fan controller
    that turns off an AC and runs a fan when it's cooler outdoors, and turns off
    a heater and runs the fan when it's warmer outdoors and the air is dry enough
    so there's no chance of condensation:

    TU System 128mb ram + 512mb flash + Desktop Linux = $115 from

    It uses 15 watts. Is there a way to reduce the power, and does it
    have 256 or 512M flash memory? It also comes with a wireless option.
    We found Atmel BASIC constraining, altho your displays seem nice.
    Does it have a Roman numeral arithmetic package? My first programming
    language did, with error messages like "wrong Roman constant."

    We are planning to use 2 $44 TAI 8540A 1-wire RH & temp sensors from
    and a $27 DS9490R 1-wire adapter, with OWFS as a 1-wire driver, and an X10
    interface, eg the $69 2414u from or
    Home Depot (are these too smart to program via linux?) with X10 controllers
    for an AC, a heater, 2 fans and a damper, eg $11 15 amp AM466s from has more fun stuff.

    We are also looking at bwbasic, which appears to be about as old as gwbasic.
    Here's an ASHRAE 55-2004 comfort calc done both ways:

    50 CLO = 1'clothing insulation (clo)
    60 MET=1.1'metabolic rate (met)
    70 WME=0'external work (met)
    80 TA=19.6'air temp (C)
    90 TR=19.6'mean radiant temp (C)
    100 VEL=.1'air velocity
    120 RH=86'relative humidity (%)
    130 PA=0'water vapor pressure
    140 DEF FNPS(T)=EXP(16.6536-4030.183/(TA+235))'sat vapor pressure, kPa
    150 IF PA=0 THEN PA=RH*10*FNPS(TA)'water vapor pressure, Pa
    160 ICL=.155*CLO'clothing resistance (m^2K/W)
    170 M=MET*58.15'metabolic rate (W/m^2)
    180 W=WME*58.15'external work in (W/m^2)
    190 MW=M-W'internal heat production
    200 IF ICL<.078 THEN FCL=1+1.29*ICL ELSE FCL=1.05+.645*ICL'clothing factor
    210 HCF=12.1*SQR(VEL)'forced convection conductance
    220 TAA=TA+273'air temp (K)
    230 TRA=TR+273'mean radiant temp (K)
    250 TCLA=TAA+(35.5-TA)/(3.5*(6.45*ICL+.1))'est clothing temp
    260 P1=ICL*FCL:p2=P1*3.96:p3=P1*100:p4=P1*TAA'intermediate values
    300 P5=308.7-.028*MW+P2*(TRA/100)^4
    310 XN=TCLA/100
    320 XF=XN
    330 N=0'number of iterations
    340 EPS=.00015'stop iteration when met
    350 XF=(XF+XN)/2'natural convection conductance
    360 HCN=2.38*ABS(100*XF-TAA)^.25
    380 XN=(P5+P4*HC-P2*XF^4)/(100+P3*HC)
    390 N=N+1
    400 IF N>150 GOTO 550
    410 IF ABS(XN-XF)>EPS GOTO 350
    420 TCL=100*XN-273'clothing surface temp (C)
    440 HL1=.00305*(5733-6.99*MW-PA)'heat loss diff through skin
    450 IF MW>58.15 THEN HL2=.42*(MW-58.15) ELSE HL2=0'heat loss by sweating
    460 HL3=.000017*M*(5867-PA)'latent respiration heat loss
    470 HL4=.0014*M*(34-TA)'dry respiration heat loss
    480 HL5=3.96*FCL*(XN^4-(TRA/100)^4)'heat loss by radiation
    490 HL6=FCL*HC*(TCL-TA)'heat loss by convection
    510 TS=.303*EXP(-.036*M)+.028'thermal sensation transfer coefficient
    520 PMV=TS*(MW-HL1-HL2-HL3-HL4-HL5-HL6)'predicted mean vote
    530 PPD=100-95*EXP(-.03353*PMV^4-.2179*PMV^2)'predicted % dissatisfied
    540 GOTO 580
    550 PMV=99999!:pPD=100

    19.6 86 1 -.4778556 9.769089

    After removing the comments with something like

    sed "s/'.*//;" gwfile.bas > bwfile.bas

    and adding back 'THEN's which bw complained were out of spec, eg in

    410 IF ABS(XN-XF)>EPS GOTO 350

    we got

    19.6 86 1 -0.4778564 9.7691115

    which seems close enough :)

  2. Guest

    We just looked at that. No USB port?
    Sounds good. I wonder if we can store everything in the TU flash and
    power down the power supply 99% of the time.
    A 60 Hz Turing machine might work :)
    That's sorta where we started.
    Right... I bought one of those for engineering calcs when I worked
    for Control Data, over humongous objections :) I have something
    older in my attic with cassette tape I/O.

  3. From a guy that spent a few K$ automating his building, MOV's and any
    other transient protection you can put on a piece of wire will pay
    itself back over and over. Zeners ad resistors are your frind,too.

    God hates silicon attached to wires. At least he does in Liberty,TN.
  4. That was the meaning. Lightning surges burnt out most of my system
    before I added surge suppression to all sensors,switches, and the
    like.It only takes a short length of wire to have a larged induced
    voltage on it from a nearby lightning strike.

    I think to date I have lost 4 CCTV cameras, 3 LM35 temperature
    sensors, several LED's, and 6 or so solid-state relays. All were
    connected to some length of (shielded) wire or coax.
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