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Thermometer Recommendations

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Eric Johnson, Nov 16, 2007.

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  1. Eric Johnson

    Eric Johnson Mod Emeritus

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    I need to rig up some thermometers in my tank so that I know what's going on. While I'm impressed with nofossil's instrumentation capabilities, I don't have the technical know-how or interest in getting quite that fancy. What I would like is two or three remote-sensing, digital thermometers in the right range, i.e., going up to 200 degrees or higher. Nofo made a couple of good suggestions in another thread. Meat thermometers are always an option for me. They can be attached to a pipe and give a pretty accurate reading, in my experience. However, I doubt anyone makes a remote-bulb meat thermometer, though I haven't shopped around, so I really don't know.

    Another possibility nofossil suggested would be conventional indoor/outdoor thermometers, but he said that you absolutely can't get the sensor wet, which kind of precludes their use in the tank. However, it occurs to me that if I put the sensor between the liner and the insulation, the sensor would stay dry and the only thing between it and the water will be 45 mils of epdm rubber. Any thoughts on whether that would give an accurate reading if positioned at the bottom of the tank, with perhaps another one near the top?

    As long as there's flow, meat thermos attached to pipes going into and out of the tank should be good enough, but I'd like to monitor the status of the tank even when nothing is moving. Maybe that's not an issue; I confess I really haven't thought that one through, either. Some days it's easier to make long-winded posts and let others do the thinking for you.

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  2. Nofossil

    Nofossil Moderator Emeritus

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    I got no energy for fresh thinking, so here's some old thoughts:

    Sensor behind EPDM would work fine. There's some possible issues with the edges of the tank not being representative, but that's what I did for early trials.

    My final (hopefully) solution was to take a 5' length of soft copper and flatten/solder one end. I got a 6' length of 14ga copper wire (for stiffness). I then ty-wrapped my sensors to it at the desired intervals and slid the whole assembly into the soft copper pipe, which is immersed in the tank with the top end in dry air. That way, I know exactly the depth of each sensor, they're in the middle of the tank rather than the edge, they're dry and protected, and I can inspect / replace them at any time.

    Since my tank is metal, I actually welded in a stainless nipple and connected the soft copper to it on the inside. The soft copper makes a gentle arc from horizontal at the edge to vertical by the time it reaches the bottom. Before adding water, I measured how far in each sensor needed to be to be at the depths that I wanted.
  3. Eric Johnson

    Eric Johnson Mod Emeritus

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    Great idea. Thanks. That's not so hard.

    The behind-the-liner trick might work OK for me, since my hx will be pretty close to the walls of the tank.
  4. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    eBay item 200172163131 ?
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    I like that, BB! I don't like the $50 part, but it looks to me like I can have one display mounted on the tank, and carry the other one around with me if I like. Keep it in the boiler room or somewhere in the house. That way my wife will know when to fire the boiler without having to descend into the dark, dingy basement.
  6. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    It is a Maverick BBQ thermo so you can probably find it other places both on ebay and locally cheaper. Retail on it is 59.99.
  7. Nofossil

    Nofossil Moderator Emeritus

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    I have a wireless BBQ thermometer that I got from HD for under $30. Only hassle is you need two sets of batteries that die on different schedules. Cool toy, though...
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