Searching for a good DIGITAL stove thermometer

[fishboat]

As I was reading through this I kept saying to myself...you guys need to look at Omega Engineering's catalog. What you're describing is a basic monitor-alarm system that is VERY common in industry. I'm surrounded by such things as we 'speak'. If you can locate an instrumentation support person at any industrial site that deals with temp-control you'd have an answer from the horse's mouth...so to speak...including 232 hookups... I used thermocouples & digital readouts (the readouts can be located anywhere, simple wiring) in a hobby brewery I built.

Another option for ideas is to look at scientific lab-supply catalogs (VWR Scientific, Fischer Scientific) as they have many options for temp monitoring, graphing...etc..

Another option for surface temp readings is an infrared sensor that you point at surfaces and read the temp from a distance.

Many of the industrial-lab solutions will be pricey, but it may give you a lead to search for inexpenisive options.

 

[cbrodsky]

As I was reading through this I kept saying to myself...you guys need to look at Omega Engineering's catalog. What you're describing is a basic monitor-alarm system that is VERY common in industry. I'm surrounded by such things as we 'speak'. If you can locate an instrumentation support person at any industrial site that deals with temp-control you'd have an answer from the horse's mouth...so to speak...including 232 hookups... I used thermocouples & digital readouts (the readouts can be located anywhere, simple wiring) in a hobby brewery I built.

Another option for ideas is to look at scientific lab-supply catalogs (VWR Scientific, Fischer Scientific) as they have many options for temp monitoring, graphing...etc..

Another option for surface temp readings is an infrared sensor that you point at surfaces and read the temp from a distance.

Many of the industrial-lab solutions will be pricey, but it may give you a lead to search for inexpenisive options.

Yea, I am familiar w/Omega - no question with a $500 budget, all this can be done easily. But as you note, it's considerably more expensive than products targeted towards specific industries such as HVAC that rely on type-K wide range thermocouples. I used them all the time in grad school working on a vacuum deposition system and it is certainly a good one stop shop for nearly anything along these lines. I did find they have good inexpensive high temp sheathed thermocouples that would be appropriate for use in a stove setting.

Similarly, I could also do this quickly with a National Instruments Lab View setup but you pay a big premium for that ease of use there as well.

From all the digging I did, assuming a $100 budget, the Mannix device I listed a while back was the closest thing I could find, so the options seem to be either pay a lot more for an off the shelf solution, or custom build something.

-Colin

 

[cbrodsky]

this can do it for $300. (without audible alarms)

(broken link removed to http://www.omega.com/pptst/iTCX.html#tc)

Nice! My stove could e-mail me at work to tell me to come home and take care of it

The interesting thing is that in a couple more years, there probably will be a $100 off the shelf device that does everything we ask and then some... that's the great thing about the semiconductor industry roadmap! Work us like dogs but every year it's amazing how much more you get get for the $ when you buy electronic devices

-Colin

 

[MikeS]

My experience with the purchased industrial stuff is that there is always some little thign that screws up the whole deal. Like, "it can't be behind a proxy" or "it has to strobe the whole page to refresh (instead of java applet)" or "it can email, but it cannot authenticate (so it won't work on mainstream internet accounts", etc, etc. That is why I have done so much work with embedded systmes like from Z-World.

I think what I will end up doing is intalling two type K TCs, one above and one below the cat, and leave the little yellow plugs hanging out the back of the stove. then I will just buy one or more TC readout meters (the cheapest are probably at places like Harbor Freight).

If I find myself using the info a lot, I will revisit the stove-powered temperature display idea.

ms

 

[Gooserider]

Well, I've said it before, - the lab stuff is great from an "isn't that cool" factor, but it's totally over the top from a budget standpoint. Same deal seems to be the case with all the automotive guages folks have come up with. (which look suspiciously like they all come from the same manufacturer with different faceplates slapped on...)

What I'm thinking we need from a "form factor" and cost basis is something like those digital thermometers used for cooking roasts and such in the oven. Definitely not the highest tech solution, but I would say they represent the minimum ideal. They come with a nice display, a settable alarm, a package that would be reasonably easy to mount, last for ages on a battery, and can be had for under $10.00! The only things that would need changing to make them work as a stove thermometer would be a different probe and a change in the display calibration.

Now to build something fancier...

1. AC power (but possibly keep the batteries for backup) - wall warts are easy.

2. Add a few more inputs - two to four would be nice, much more than that would probably be overkill. When Elk and I were visiting the VC plant, it didn't look to me like they used more than a half dozen or so probes on their test stoves in the thermo lab.
Each probe ideally should have the ability to set 3-4 trigger points / zones - something like "cold, ideal, getting hot, and "OH $#!%"

3. The display should be big type - at least 1/2-3/4" high, an inch would be better. LCD or LED would be fine, LCD is better for power, but would need a backlight. If the unit had multiple sensors, I could see having either all of them displayed at the same time, or just one displayed with an indicator for which. However, I would rather have fewer sensors displayed with large numbers than all of them with small numbers - the idea is that you should be able to read the display from accross the room, easily.

4. It would also be nice if there was a set of status LED's or a color changing backlight to give a visible at a glance indicator of whether there was an alarm condition or not.

5. Alarms - There should be a LOUD, "snoozable", but not "cancelable" alarm that will trigger at a user configurable set point (per sensor) that says an overtemp condition exists. It is desireable to have additional alarm sounds, but these should be optional, and either "snoozeable" or "cancelable". These extra alarms might have several sounds, but they should be different from the overtemp alarm.

6. Communication - I would love to see some kind of interface on the box, I think Ethernet (cat5e) would be best for versatile hookup. Protocol should be standard, and the data format should be easily parsed without needing anything special on the other end. Specifically the box should be able to work with systems running Linux or any of the other less capable O/S's

I'd be really interested in a box like that, what would it be likely to cost? What sort of commitment would it take to get someone to build something like it?

Gooserider

 

[velvetfoot]

Let's say I was thinking about putting in a gauge. For an insert, where would be the best place to drill a hole? Where in the interior are you trying to measure the temp? Would right below the tubes be good?

 

[MikeS]

there are many ways to do it. One thing many people may not know is that the TC junction can be two junctions with non-thermocouple (not exactly true, but you get the point) metal between. in this case, the indicated temp is the average temp of the third metal.

For example, a kettle of wort for brewing beer could be measured without touching the fluid by attaching the cromel wire to one side of the pot and the alumel wire to the other (or anywhere on it) and the indicated temp would be the average of that piece of metal between (the pot, in this case).

so for the insert, one could measure the metal temperature without drilling through it. to measure the actual combustion gas, though, the junction should be in the process stream.