Infared Thermometers

Barry, I would not get rid of your existing thermometer. As I understand it an infrared thermometer is only ‘good’ at reading surface temperatures.

You want to ‘probe’ your mash don’t you?

http://www.thermoworks.com/blog/2012/03/infrared-thermometry/

Cheers!

 

Not only that, but if there is steam rising from the surface, you get that temperature and not the temperature of the surface. A friend constantly used one and got many different readings depending on where he aimed the beam. I finally convinced him to give up on the infrared thermometer and go for a probe thermometer.

 

I am guessing that infrared thermometer will get a lot of use!

Cheers!

 

I use infrareds at work all the time and can say with authority that they basically suck for anything that a probe thermometer can also be used in. Now if you gotta know the temp of molten metal, the infrared is your friend.

 

I got a cheap one to measure the temp of my beer in the fermentor. It kinda looks like a gun and has a laser on it. It worked great for the beer and for fun while drunk for about 3 weeks. Then one of my friends stole it.

 

Yeah I guess that's not fair to say, what I mean is for accurate measurements in many situations they are not very good, I regularly get temp differences of 3-4 degrees F from one infrared to another, and compared to a thermocouple thermometer. Their accuracy is very dependent on the surface being tested (reflectivity, light absorbtion, etc.), and as mentioned earlier, things like steam mess up readings. If exact temps are not needed, and quick testing without disturbing what your checking is critical, they make sense. IMO for homebrewing they are not a good option as your sole thermo, but fine as a quick check between actual measurements.

 

I have one, it's on par to the decimal point with my digital thermometer. I doubt it sometimes, but every read is exactly the same when I compare.

 

I bought one for $11 from China on ebay a couple years ago. You need to finesse an accurate-ish reading from it and, even then, I don't have a lot of confidence in it. I had planned to use it around the brewery for non-critical stuff but it seems to have a range of +/-20 degrees, so it's kind of useless. The only thing I use it for now is to check when the flat top is ready for the pancakes - a 20 degree error is not that big of a deal for that. FWIW, I got a refund from the seller when it was clear that this was a POS, like most of the stuff you get from China on ebay, much of it for half the price of shipping, alone, which is usually free (I wish I understood their business model).

 

I also have one that is quite accurate. But it's not the accuracy of the gun itself that matters, it's the surface area (emissivity) and conditions that cause the variabilities. Some surfaces provide inaccurate readings. Also, liquids (especially hot) cause all kinds of variability in temperature readings, especially if the water is boiling or if there is steam coming off the surface. A fogged lens on the gun can also cause errors in reading as can dust in the air or any other condition that obscures the optics between the gun and the surface. For brewing, the liquid conditions become critical, so an infrared thermometer is not as accuurate as a probe thermometer. However, the infrared thermometer is OK for reading the temperature of the side of a carboy that contains a beer that is fermenting. You can get fairly accurate readings for that purpose (as long as the emissivity of the reflective glass is taken into consideration - some infrared thermometers can adjust for emissivity). Copper, aluminum and stainless steel are also highly reflective and can give improper readings. But if you wish to use it for mashing or extract brewing, it's far better and more accurate to use a probe thermometer.

 

Here are a few things for which the IR thermometer might be useful:

1. For measuring the temperature of the grain before mashing (stir the grain first and take a few measurements on the surface). This can be used for measurements involving the target temperature of the strike water;

2. For measuring temperatures around your house (e.g. basement, fruit cellar, unheated rooms, etc.) if you wish to ferment your beer at a certain range of temperatures;

3. For measuring the temperature of the outside of your carboy during fermentation. Again, you have to adjust for the emissiviity of the glass. Also, you will be measuring the outside of the carboy which is in contact with the ambient air temperature, so it will likely be a few degrees different than the fermenting beer (same as adhesive temperature strips); and

4. For measuring the approximate temperature of water as it is being heated for the mash or sparging, etc. Make sure you first stir the water, measure while it is still in motion, and that there is no steam rising from the surface. You have to be careful that the IR thermometer is reading the water and not the inside of the container wall, as the side could be a little different as it is exposed on the outside to the ambient air temperature and also in terms of its emissivity.

It will not be useful for measuring the temperature of the mash since you can only read the outside of the mash tun (often insulated and exposed to the ambient temperature) or the surface temperature of the mash. The surface is exposed to the lower air temperature after you opened the mash tun, so it will be at a significantly different temperature than the temperature in the interior of the mash. If you first stirred it, you could increase the accuracy of the reading, but the surface will always be exposed to the air so it won't be completely accurate.

 

Like OB said, their great for the outside of carboys but for mashing or wort it's useless.

 

they are very good for technicians who need to measure the surface temperature of asphalt as it is being applied. they are cheap, accurate to within a few degrees and when they get dropped into a batch of hot mix they melt nicely. it's almost as if you don't care that you are buying 4 or 5 every summer.

in the home brewery i use my Thermoworks RT 6000. As everyone else has said, even the good IR probes aren't very accurate. they are fun to use though. mine has a laser. an actual laser beam! weeeeee!

Cheers.

 

I use mine for my wood fired pizza oven when I need to know when the deck is ready. +/- 25*. They are terrible for mash temps.

 

I was gifted an infrared recently and honestly, I have not used it at all yet. However now you've got me thinking about ways that I could use it. First, since I mash in a bag in my stainless kettle, I think I'll try it in addition to my usual mash thermometer and calculate a correction factor if necessary on both the outside of the kettle and the surface so that I can quickly determine the most likely core mash temp. Second, it's easy enough to pop the airlock off a fermenter for 10 seconds and shoot the gun inside, so I think I might try that tonight on my ESB in primary to see how that compares with the outside measurement. There's stuff can be done I think, but you need to understand that you might need to correct and swag to get a more realistic number. Figure out some correction factors or addends, and apply as necessary.

Yes, I'm a scientist and math dork. And you too can use this knowledge and gain your own experience and use it to your advantage. Cheers.

 

I think you forgot:

5. Keep your cat occupied. That's all I use mine for.

 

The most important part! They love chasing that light!