Ideas for accurate temperature measurement and control during the boil

Hi everyone! I'm a new home brewer (I think we've done 5 batches now) and I'm looking for some ideas/creative solutions around temperature monitoring and control during the boil/mash process.

Our set up: We are using a 7.5 stainless steel gallon pot on a two-burner outdoor propane canning stove. To monitor the temperature, we have tried different thermometers (regular and digital).

Our problems:

1. Because we are manually taking the temperature at different times, we are not able to monitor the temperature throughout the boil. Without buying expensive, professional grade equipment, how can we measure the temperature the whole time? Any ways to monitor the kettle? Or, recommended thermometers/techniques?
2. Our boil also seems to be different temperatures depending on where we stick the thermometer. Any ideas for this problem? I want to make sure we're boiling at the right temp, right now it seems like kind of a crap shoot

Thanks everyone! I'm excited to see what you are all doing to solve these problems!

-Kim and the LTD Home Brew Crew

 

Just to confirm, you want to measure the boil temp or the mash temp? Monitoring either can be accomplished with a weldless thermometer mounted in the mash tun and/or boil kettle as long as they are calibrated well. It is a bit different in the mash in that without some type of constant recirculation system you can easily get different temps in different parts of the grain bed if it is not stirred well enough. As far as the boil goes I really don't monitor it TOO closely as it comes up to temp. Once I get a rolling boil, and adjust the burner to just maintain that, I don't care what the temp is.

 

The boil should always be 212*F (depending on sea level it may vary slightly). You probably have a defective thermometer. I suggest buying a new one. In particular this one:

http://thermoworks.com/products/low_cost/rt600c.html

 

Hi there! I guess I'm thinking more about the mash (although during the boil, we were afraid that the temp was getting to high and would negatively affect the hops...have you found that the temp doesn't affect the flavor/aroma that much?).

Thanks for the idea with the weldless thermometer...I haven't heard of those before! Is there one that you would recommend in particular and do you have any tips to make sure that its calibrated well?

Also, do you have any tricks for circulating the grain bed? We've just been stirring with a large spoon.

 

Once it's boiling it's boiling.

You don't need to monitor boil temperature. You will never exceed 212F/100C.

 

Thanks Smellyglove and grathan. Do you have any tips for monitoring the mash or for controlling the heat more? I know that I have a very basic set up, but I'm hoping to get some tips on how to modify it to make it a more controlled process.

 

What are you using for a mashtun? There are weldless kits for thermometers for cooler as well as keggles/kettles. Most homebrew stores online have them like this:

http://brewhardware.com/measurement-devices/thermometers-71/88-dial-thermometers

If you go with this company, you an contact Bobby who runs it and is always helpful. Let him know what you are looking to do and he will get you set up.

 

Tell us what your setup is and how you do it.

 

Most probe thermometers are adjustable, put Luke warm water in a glass and fill with ice then use wrench to turn your temp to 35 degrees, I do mine every batch, have been off 20 degrees before


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We are using a 7.5 stainless steel gallon pot on a two-burner outdoor propane canning stove. To monitor the temperature, we have tried different thermometers (regular and digital).

 

Wow! That keggle looks awesome! have you made one before?

 

Like I said. Actualy no use in monitoring boill temps. The only reason you'd want to monitor the temp inside your BK is if you have an automated heater and you'd make sure it keeps a boil with minimum amount of ernergy applied. Or else you'd just corrct it visually. Or to monitor chilling temps, which I guess you do anyway.

When it comes to maintaining mash-temps, a pump used for recirculation is a tip.

 

What kind of pump do you use?

 

Boiling point of wort is not exactly 212F. Anything dissolved in water will raise the boiling point. For a 1.040 beer that’s approximately 10°P, or 100g/L for a .27°F boiling point elevation.

Speaking of elevation you can subtract 1°F for every 500 feet above sea level. Weather counts too, but unless you’re in a hurricane, not much.

So at 500 feet elevation at 29.92" barometric pressure a 1.040 wort will boil at 211.27° F.

Not a big deal, unless you’re trying to calibrate your thermometer to boiling wort. As mentioned earlier a slow boil is the same temperature as a fast boil. All we really care about is the boil-off rate.

On the other end, a proper ice bath is more ice than water, and is stirred continuously, and is reliably 32.0°F. Ice water could be about anything below room temperature and above freezing, usually about 40°F.

 

Just to check, are you doing extract or all grain brewing? If you are doing extract don't worry about this talk to mash tuns for the time being, because the people who make the extract already did that.

A thermometer in the boil kettle tells me 2 things, how close I am to a boil, and how much further do I need to chill.

While the boil is where some of the most complex chemistry in brewing takes place, lucky for brewers it is also one of the easiest to control. While temperature does play a role hop reactions, there are other reactions which require more heat. During the boil DMS is generated, and needs to be volatilized off. You need a vigorous boil to make sure the DMS stays out of the beer. As long as you have a nice rolling boil you are fine. Tweaking the boil-off rate will impact the melinoidan formation, and your final gravity, both of which really just require consistency, vs a specific measurable value.

As for temperature in the boil, physics will not allow you to boil too hot. If you are getting different temperatures in various locations in the kettle while boiling, either your thermometer is wrong or you are not boiling vigorous enough. A vigorous boil will cause a turning motion of the fluid in the kettle, mixing everything. What the actual temperature of the boil is really is a moot point, it will be 212 F, with some variability for the various corrections listed above. But in the boil the temperature is not the issue, the chemistry is not that particular. You are well in the range where the reactions will happen appropriately.

If you are talking about the temperature while steeping grains, then the temperature is important, but make sure to stir the the water well (same with hot liquor) before reading the temperature.