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  1. #16
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
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    Perth
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    7,182

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    Quote Originally Posted by Stustoys View Post
    Hi Bob,
    Well only for the 20 hour run in. Also it isn't an open fire if that helps, on the down side I have two small diesel trucks...... but I only use one at a time
    Closed fire place is supposed to be significantly better than open fireplace for PM2.5, but significantly worse than a wood pellet stove which still has issues.
    It turns out any form of combustion is bad whether its fireplace or engines.
    We now no longer heat or cook with gas at our place as SWMBO has health issues with these. It appears she might be a bit of canary.
    I have PM2.5 monitors running all the time and just frying an egg (let alone bacon) without running the kitchen extractors sends it up above unhealthy levels. Baking is also pretty bad - I tell SWMBO that means our oven is dirty

    On the code side of things I'm about 80% confident I'm good to go, just waiting on the RS-485 Module. Just ordered another one from an(fingers crossed) Aus supplier, as the ones I ordered China over a week ago don't seem to have moved.
    I fortunately order a heap of Arduino stuff from China in early Dec and it has now all arrived. Pity my enthusiasm is low for project work has not matched my supplies.

  2. #17
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

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    Quote Originally Posted by BobL View Post
    I tell SWMBO that means our oven is dirty
    Brave man! I'm surprised you haven't been given a job. lol
    I was thinking about adding a CO monitor to the flue but I couldn't find something that would do the job. Perhaps I could infure something by using a car O2 sensor, but I decided to leave that until MK3 at least. Given that I cant actually build the thing ATM I keep coming up with ideas to add to something that I dont even know if it works yet lol

    Quote Originally Posted by BobL View Post
    I fortunately order a heap of Arduino stuff from China in early Dec and it has now all arrived. Pity my enthusiasm is low for project work has not matched my supplies.
    Here's hoping your enthusiasm returns shortly. Mine sure comes and goes.
    You making coffee machine Mk28?

  3. #18
    Join Date
    Jul 2010
    Location
    Melbourne
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    9,088

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    My code, well ok 3/4 of it is taken from the other guys. There a few things I still don't understand but it seems to do what I want.
    I cant test it with a VSD until my card turns up.
    It uses an LM35DZ on A0
    Not sure there is a need to not repeatedly send the same speed to the VSD, just seemed silly to. Though I doubt the Arduino would burst into tears lol
    Lots of prints so I can see whats going on atm and a 5 second pause at the start.


    Think of it as an offsite back up

    #include <SoftwareSerial.h>


    int fanspeed;
    int StartWaitTime=5000; //power on boot time of VSD minus boot time of Arduino in seconds times 1000
    int minfanspeed=1000; //Min Hz the VSD will be run at times 100
    int maxfanspeed=5000; //Max Hz the VSD will be run at times 100
    int fanspeedstep=100; //Change in speed step size in Hz times 100
    int FanSpeedUpTemp=27; //DegC at which the fan will increase speed
    int FanSlowDownTemp=25; //DegC at which the fan will decrease speed
    int ReadDelay=1000; //Wait between temperature readings
    int FanSpeedOld; //To stop HEX being sent to VSD unless it has changed since last send
    float temperature;
    float sensorValue;
    float powerVoltage=5;//define the power supply voltage.


    String speed=":010203030BB837\r\n";


    char* read_speed=":01040300";
    char* change_speed=":010203030BB8";
    char* stop=":01030108";
    char* start=":01030101";


    SoftwareSerial myserial(11,8); // RX, TX






    void setup() {
    Serial.begin(9600);
    fanspeed=minfanspeed;
    delay(StartWaitTime);
    pinMode(9,OUTPUT);

    pinMode(10,OUTPUT);
    myserial.begin(9600);
    digitalWrite(9,LOW); digitalWrite(9,LOW);
    }


    void setSpeed(int v) {
    Serial.print("Set new speed "); Serial.println(v,DEC);
    char* n=change_speed;
    //char n[13];
    //strcpy(n,change_speed);
    n[9]=toHexa((v/256)>>4);
    n[10]=toHexa((v/256)&0xf);
    n[11]=toHexa((v&0xff)>>4);
    n[12]=toHexa((v&0xff)&0xf);

    Serial.println(n);
    query(n); // set new speed
    }


    void loop() {
    sensorValue = analogRead(A0); // read the input on analog pin 0:
    temperature=(sensorValue/1023)*powerVoltage*100;
    Serial.println(temperature); //uncomment when I want to see if it is looping
    delay (ReadDelay);
    if (temperature > FanSpeedUpTemp && fanspeed<maxfanspeed) {fanspeed=fanspeed + fanspeedstep;}
    if (temperature < FanSlowDownTemp && fanspeed>minfanspeed) {fanspeed=fanspeed - fanspeedstep;}
    if (fanspeed != FanSpeedOld) {
    Serial.print("The room temperature is: ");
    Serial.print( temperature,1);
    Serial.print(" raw temp data: ");
    Serial.print(sensorValue);
    Serial.print(" fan speed is: ");
    Serial.println(fanspeed);
    setSpeed(fanspeed);
    FanSpeedOld=fanspeed;
    }
    }


    void transmit(String msg) {
    // activate driver
    ;
    digitalWrite(9,HIGH); digitalWrite(9,HIGH);
    delay(50);
    myserial.print(msg);
    delay(1);
    digitalWrite(9,LOW); digitalWrite(9,LOW);
    }


    char hexa(char byte) { // return hexa value of that ASCII char
    if(byte<='9') return byte & 0x0f;
    if(byte<='F') return (byte & 0x0f) + 9; // A=0x41 --> 0x0a
    }

    char toHexa(int i) {
    if(i<10) return 0x30 | i;
    return 0x41 + i - 10;
    }


    char crc(char* buffer) {
    int l=strlen(buffer);
    int i=1;
    int chk=0;
    while(i<l) { Serial.print(hexa(buffer[i])<<4|hexa(buffer[i+1]),HEX); chk+= ( hexa(buffer[i])<<4|hexa(buffer[i+1]) ); i+=2; Serial.print(" ");}
    Serial.print(":");

    Serial.println(chk,HEX);

    Serial.println(0x100-chk,HEX);
    return (0x100-chk) & 0xff;
    }

    void query(char* cmd) {
    char lrc = crc(cmd);
    String msg = cmd;
    msg+=toHexa((lrc&0xf0)>>4);
    msg+=toHexa(lrc&0x0f);
    msg+="\r\n";
    Serial.print(msg);
    transmit(msg);
    }

  4. #19
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

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    G/day Stu, in my last house I had a high ceiling in the lounge kitchen area, i used scissor trusses there so i spoze it was 11 ft high through the centre of the room. The rest of the house had 9ft ceilings.
    Had a coonara wood heater in the lounge and that worked well in the lounge only, i was on solar power
    and needed to get some heat down to the other end of the house.
    So I put in one of those flexable ducts with a fan roughly in the centre point of the duct and pulled the hot air from a wall grill near the ceiling above the heater and sent it down to the other end of the house, so the hallway and bedroom doors were left open and in theory the air would circulate from the lounge near the ceiling down to the other end of the house and back down the hallway to the loungeroom and at least take the chill off the rest of the house.
    The fan had a speed knob and if the speed was turned up more than a quarter it seemed to cool the warm air coming through the duct, any lower than quarter speed and the air speed was too slow and would also cool before before it came out the duct, but at the sweet spot it worked really well.
    I had an audible thermometer that i tested this system with, if the temp was too low it would whine at me continuously, I'M COLD I'M COLD........
    cheers, shed

  5. #20
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
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    Hi Shed,

    No speed control on my fan, but from memory its only a 14W fan in 17m of 8" duct into a Yee* to 2 x 3m of 6" with a really crappy 90deg bend into the ceiling vent. So it doesn't seem to flow much air but it does do the job if running all the time. The temp lose is huge though, while I don't have the actual numbers handy something along the lines of 80C inlet 30C outlet is likely not to far off the mark. So I am looking at making some improvements there or at least getting some of it back with my new fan. while getting some proper 90deg turns into the vents would be a start, after that I'm not sure which or which combination of bigger fan, bigger ducts, more insulation is the way to go. I'm a little concerned about making to much improvement between the heater and the fan as I wonder just how hot you can run the fan?

    I like your alarm! lol
    I have 7 thermometers scattered about the place.

    *it may even be a Tee been awhile since I was up there.

  6. #21
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

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    Hi Stuart, Guys,

    I would definitely put insulation around the duct, particularly if its metal. You will loose most of the heat over that distance. As far as the fan goes, I don't think that it is going to get very hot unless it is right over the heat source.

    One of the workshops that I visit occasionally has a hot air heating system, a very large steel box that is oil fired and has three large moveable vents on top that blow the hot, enough to be uncomfortable to your hand, air out over the workshop. It has what looks like a 1 HP fan motor in there, which is mounted almost directly above the burner chamber. It gets quite hot inside but its been like that for as long as I've been visiting, which is several years. I've lubricated the motor bearings several times.
    Best Regards:
    Baron J.

  7. #22
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

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    Hi Baron,

    The ducting after the fan is the standard flexible ducting(I cant even remember what its called lol) . If I recall correctly its R0.6. The ducting between the heater and the fan is a higher temp rating I believe, but "eyeballing it" it would be about the same R value. So certainly room for improvement, but it will be painful.

  8. #23
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

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    Hi Stuart,

    From your description It sounds like that plastic stuff that has a wire spring inside ! If it is then it is intended to be used for bathroom air and steam extraction. I/we use it for this purpose, also in the kitchen for the hob extraction fan.

    Since in my case heat loss doesn't matter, I've done nothing with it.

    You could wrap it with pipe lagging, that will reduce heat loss quite a bit.
    Best Regards:
    Baron J.

  9. #24
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
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    Hi Baron,

    It is stuff with the spring, but it is heater ducting, it has insulation.

  10. #25
    Join Date
    Jul 2010
    Location
    Melbourne
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    Well it appears my(the) code works.
    My RS485 board turned up Friday. I connected the VSD and got nothing. Messaged the guy whose code I butchered to clear up some warning messages I was getting. He said it was fine and it should work. Tried a few more things with no result then got my scope out*.
    And think I know where the problem is.
    The first screen is a .5V test signal on channel 1
    Second screen is the Arduino output on channel 2
    Third screed Arduino off VSD on.
    Fourth screen Arduino output with VSD on.

    So to me it looks like the Arduino side of things maybe working but there is to much noise from the VSD? I know RS485 is meant to be able to handle noise. but that much?
    Am I missing something?


    PWM is starting to look easier


    *no capture on the scope so I just removed all the delays from the program so it had a pretty constant output.
    Attached Images Attached Images

  11. #26
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    Jul 2010
    Location
    Melbourne
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    Well now I know my welder is dead I can get back to trying to make thing thing work.

    Was on the roof cleaning the chimney today so fitted a thermcouple to the top of the chimney. I've even thought of a use for it, it will let me know when the fire is out so I can turn off "make up air". I wonder how long it will last.
    Attached Images Attached Images

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