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Thread: Temperature Monitor in my shop

  1. #1
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    Temperature Monitor in my shop

    Thinking as I type... I'm having an issue with the furnace in my shop and when it's cold I may not go out there for several days at a time. Once in a while the pilot light in the furnace will go out, thermostat is telling the furnace to turn on the heat which turns on the blower but with the pilot out it never warms up the shop enough to turn the furnace off. The result is I find the shop at 30 deg with the furnace fan running when the thermostat is set for 50. Have to keep some heat going to keep the water lines from freezing.

    I need a way to know when the temperature in the shop is well below what I have the thermostat is set for. I do have a cat-5 network cable to the shop and can keep a computer on. Thinking of using a Teensy 2.0 with a temp sensor salvaged from an old computer cooler. I have the temp sensor working with a Teensy but am trying to figure out the easiest way to have it report to me when I ask it to. I can write a Windows program to either send me an email or maybe use the network to talk to one of my computers in my office. Email may be the best option as I could receive it from one of several devices and computers.

    This leaves the communications link between the computer in the shop and the Teensy. Could I just use the USB serial port? Send a command to the Teensy that tells it to read and report the temp back out the serial port. The Windows program could determine if the temperature is below whatever value I choose and if it is then send me an email telling me I need to go check the shop.

    Does this sound feasible or does anyone have any other ideas?
    Thanks and Merry Christmas.

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    I'm wondering if you can't use the Teensy to re-light the pilot? Isn't there an electric ignition which could be triggered by one of the Teensy's IO pins?

  3. #3
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    That would be really cool but the furnace is old and the only way to relight the pilot is turning the gas valve to Pilot and holding a button in. It always lights and stays lit really easy which tells me the thermocouple is probably good. Not real sure why it goes out, seems to be random and not associated with the wind speed.

  4. #4
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    Serial is the normal tool for this, as long as your PC side programing environment has a serial option. Less elegant alternative is to make the teensy a USB keyboard/mouse and have your PC side software look for keystrokes or a mouse click to fire off an email (or even have the Teensy type the text and hit send on an always open email window).

    If you want to go straight to ethernet you can also do that, with a teensy (probably something with more lifting capability than the t2) sending network packets.

    You can probably use servo motors and some form of clamp to automatically relight things, but the result will be fragile and potentially start doing bad things to the furnance if software glitches so warning only is probably the right answer.

  5. #5
    Senior Member+ defragster's Avatar
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    Need to get a new thermocouple installed is my read. Monitoring sounds important - but pilot going out for a reason . . .

    I just swapped the Thermocouple in one of my 2 in house propane Pilot light based fireplace inserts. I bought new Thermocouples 5-10 years ago ( the heater units are now 18 years old). They started being finicky so I bought replacements - but the swap seemed ugly and I put it off and turned up the pilot flame height - that worked the last few years.

    This year the downstairs unit pilot stayed lit for some time - but then this heating season it would just be out before it would light or burn full flame very long. There is one voltage/current to open the pilot valve and then a second 'fail safe' draw to keep the big valve open. At least it seems that way as from cold lighting the pilot takes holding the indicated PILOT button some part of a minute - but for some time after that the thermostat won't engage full flame as the output won't power that second valve.
    Last edited by defragster; 12-25-2017 at 06:44 AM.

  6. #6
    Senior Member pictographer's Avatar
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    USB Serial to a Python script on the shop computer is an easy way to go.

    The same cable you use for programming you can use for communicating with your Teensy application. No extra db-9 connector or Ethernet hardware. Serial.Print() and Serial.Read() are your friends. :-)
    Last edited by pictographer; 12-25-2017 at 03:46 AM.

  7. #7
    cheap throw away type cell phone with temp sensor app to call you and ask politely to come light the pilot light.

  8. #8
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    Was fairly easy, have the app for the shop computer working pretty good. Also added a network socket so I could tell it to send an email with the temperature anytime I wanted to check it. Just need to write a small app that will send it the command.

    After all that I discovered this retro fit kit on eBay that will convert the furnace to an electronic lit pilot.
    https://www.ebay.com/itm/NEW-Honeywe...3/232584469546

    Would probably save it's cost in propane over a couple years.

  9. #9
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by BReeves View Post
    ...
    Would probably save it's cost in propane over a couple years.
    Less than one? Pilots consume a gallon about every three days from what I recall from my installers

  10. #10
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    In the meantime I have the remote temperature monitor working from my shop in it's rough state.
    Have an application running on the shop computer that checks the Teensy every 1/2 hour and if the temperature drops below 50 degrees it will send me an email. I also wrote a small app that I can run on any Windows networked computer that will send a message to the shop computer asking for the temperature reading at that instant. In case someone else finds themselves in a similar situation I ziped up the 3 files and uploaded them to my web site.
    http://www.public.somethinxtra.com/TempMonitorFiles.zip

    The ZIP file contains 3 files...
    SendMail.exe is the app for the shop computer that talks to the Teensy.
    ReqTemp.exe is the app that will send a message to the shop computer requesting a temperature reading.
    GetTemp.ino is the code that is running on the Teensy.

    This should run on any windows computer but have not tested it on Windows 10. My shop computer is running XP and this one is running Windows 7. No warranties are expressed or implied, your results may vary etc.
    The Teensy code uses the minimal example from the PJRC site with serial communications added. The exact temperature isn't critical in this application and the basic calcs are good enough. I just have the Teensy on a plug in proto board just as shown in the PJRC example.

    The SendMail.exe app has the Teensy USB port hard coded for COM-5 and 19200 baud. Need to make sure your USB serial port is configured for this before trying to run the app. If it doesn't find the Teensy port when it starts it will error out and not work. Once you have it running, you will need to configure an email account. Nothing fancy, your basic POP3/SMTP email settings as in Outlook Express. It has test buttons to make sure everything is working.

    ReqTemp.exe queries the network (Windows peer to peer Workgroup) when it starts and loads the names of all the computers on the network into a drop down control. Select the computer that is running the SendMail app and click the Send Msg button. Wait a couple minutes for everything to happen then check your email. May take a little while depending on how fast the emails travels through the net. It isn't perfect and once in a while I have to try a 2nd time for everything to happen. This is the from a quick check just a few minutes ago.

    >Sent: Wednesday, December 27, 2017 5:19 AM
    >Subject: Temperature Report From Shop

    > Shop Temperature = 64.10

    This will work for me with the next few weeks predicted to be in the teens and while I make a decision about what to do with the shop furnace.

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