Author Topic: Brewing Thermometer  (Read 1491 times)

Offline woody45833

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Brewing Thermometer
« on: August 22, 2016, 02:13:43 AM »
I would like to say hi to all and I'm a newbie only have been brewing for two years, started from Mr.Beer kit to extract then all the equipment to do all grain. I have been successful with most of my beers but lately have ran across a lot of thermometer problems. I have a mega pot and was on 3 different fermenter favorite thermometers one the glass exploded, one the needle fell off the other was just not accurate and would not stay calibrated. I took kettle to shop had thermostat hole welded up and drain valve welded for extension then the valve so O rings would not get hot from eldemetal burner heat shield worked just ok. I have been online so much everyone has been talking about the thermapen and the chef alarm. I'm not worried about the cost as much as me trying to figure out what's best for me. I was thinking thermapen to check water and wart temp in kettle as for a boil doesn't matter can see when it's boiling. The mash tun is my biggest problem I'm trying to figure out. With chef Alarm you won't want to screw lid tight will damage probe cable. So is at is important to measure mash temp constantly or just initially if you have good idea how much temp it will drop in a hour with understanding little different with amount of grains and water. I'm just struggling what is going to be best for me to use for mash water Sparge water and mash tun all in one. I understand by time you buy waterproof probe almost same cost as thermapen. Or maybe I'm going about this wrong open to suggestions and help on picking the right one for me and I do understand there is a lot of info online that is why I think I'm more confused lol Thank You.
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Offline Stevie

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Re: Brewing Thermometer
« Reply #1 on: August 22, 2016, 02:16:28 AM »
How close is the thermostat to the bottom of the kettle? Sounds like you would benefit from a heat shield.

Offline woody45833

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Re: Brewing Thermometer
« Reply #2 on: August 22, 2016, 02:41:59 AM »
How close is the thermostat to the bottom of the kettle? Sounds like you would benefit from a heat shield.
I bought a heat shield from Brewers hardware. The needle just fell of the gauge once. The other the glass blew out it had condensation in it was brewing in winter time temp changes in garage how it got condensation in it. And the 3rd one northern brewery sent me will not hold accuracy I know they have good customer service however I'm done with the fermenters favorite I know could be just dumb luck but wanting to go digital. Thanks Sorry did not really answer correctly will measure it the kettle came drilled allready I ordered it that way
« Last Edit: August 22, 2016, 10:57:34 AM by woody45833 »
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Offline pfabsits

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Re: Brewing Thermometer
« Reply #3 on: August 22, 2016, 12:51:15 PM »
Below is some information regarding thermometers. Digital thermometers are more robust than spirit filled and offer a higher accuracy. There is a wide range of digital thermometers available. Pocket meters from the grocery store will run ~$20. They have a +/-2-3 oF accuracy and are thermistor based. For under $40 a pocket thermometer can be purchased with greater accuracy (+/-0.5 oF).

All electronic devices will drift overtime and with temperature. It is inevitable. Thermometers less than $20 or ones from the grocery store are not very accurate. They usually are around 2-3 oF in accuracy. The company I work for offers pocket thermometers on the expensive side but they offer the Cal-Check function and an accuracy +/- 0.5 oF (-58 to 199.9 oF range).

Cal-Check is an internal diagnostic function of the electronics. When switched on it should display "0". Any drift will show as a deviation from "0"

Thermometers fall into three categories:
Thermistors
Thermocouples (K-type being the most common)
PT100

Thermistor is a semi-conductor device that resistivity changes with temeprature
Thermocouples consist of probe with two wires of different metals twisted together (hot junction) that have a potential difference based on temperature
pt100 is like a thermistor in which there is an increase in resistance that is measured but it is a resistance of a metal conductor (RTD) made of platinum with temperature and not a semi-conductor (thermistor - NTC, PTC).

Thermistors have limited ranges of around -50 to 302 oF and offer high accuracy
Thermocouples have very wide range based on type (K,J,T, etc). For example a K-type wire probe spec can be up to 2000 oF but not as accurate as a thermistor.
pt100 have a wide range, up to 1650 oF and high accuracy.

Thermocouples have the fastest response. The fast response time of the thermocouple is one of the reasons it is the technology chosen in restaurants. we offer probes as fast as 4 second response time to reach 90% of the value. Thermistors probes can be fast as well. We have some in the 6 second response time to reach 90% of the value.

The pocket thermistor thermometers are the most common due to price. Portable themometers will start in the +$100 dollar range. With thermocouples there are two types of calibrations. The internal meter calibration is for the "hot junction" which is where the probe connects to the meter. This has to be done with temperature controlled baths at multiple points. There are also meters with probe calibration feature in which the "cold junction" is calibrated by placing the probe in an ice bath. An ice bath should be prepared with crushed ice made from DI water. Any salts will cause freezing point depression in which the water will freeze below 32 oF. Some portable thermistor thermometers also offer a ice bath calibration feature.
One of the avid home brewers that work for Hanna Instruments

Offline kramerog

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Re: Brewing Thermometer
« Reply #4 on: August 22, 2016, 02:26:25 PM »
The mash tun is my biggest problem I'm trying to figure out. With chef Alarm you won't want to screw lid tight will damage probe cable. So is at is important to measure mash temp constantly or just initially if you have good idea how much temp it will drop in a hour with understanding little different with amount of grains and water. I'm just struggling what is going to be best for me to use for mash water Sparge water and mash tun all in one.

You haven't said what you mash tun is.  If it is a cooler, it is suficient to measure it at the start of the mash because the temperature typically does not change much.  I typically use a Thermapen for this.

For my hot liquor tank, I use a Thermoworks DOT with a waterproof cable.  I need an alarm for that to make sure that I don't overshoot the desired temp.  I also have a Blichmann dial thermometer which will match the DOT once I stir the water in the HLT.  To hit my mash temp, I have to get the water in my HLT to the right temp.  For sparge water, temp target is very wide.

Offline woody45833

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Re: Brewing Thermometer
« Reply #5 on: August 22, 2016, 09:46:45 PM »
Sorry I am using a Home Depot 10gallon Mash Tun and HLT. So suggesting dot for HLT and Thema pen for kettle and Mash tun then leave it ?
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Offline kramerog

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Re: Brewing Thermometer
« Reply #6 on: September 01, 2016, 07:21:14 PM »
Sorry for late response, you could probably use DOT for everything.

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