What Thermometer Will Be 100% Accurate - Im Willing To Pay...

[bear09]

Hi All.

I have 3 thermometers and three big bloody head aches - which one can I trust?

Glass tube mercury - ~$30.
Ebay digital probe - ~$70.
3" dial mash master - ~$40.

In ice water they all read zero. In boiling water they all read 100. When I get to mash ranges though there are 1 - 2 - 3 degs discrepancies.

Does anyone know where I can get a thermometer that is certified to be accurate? Im willing to pay for the piece of mind.

I just want to have some conviction in my temps. Anyone else experiencing this?

 

[A3k]

Are you measuring them all in the same location in the mash?

I don't have a proper answer to your question though sorry.

cheers,
Al

 

[Phoney]

I bought a $30 digital cooking thermometer from House (the kitchen supply store). has a range of -45C - 200C & increments of .1

Ive tested it with three other thermometers at mash temperatures, (including a mates lab thermometer) and it's spot on...

EDIT: looks like this:

 

[MHB]

Here is the big problem, it was spot-on, you know that what you don't know is whether or not it's still spot-on, that's why we talk about "Calibration". That's the case with all mechanical and electronic thermometers; I don't want to harp on about this (there was another thread last couple of days) Get 1 decent glass laboratory thermometer and use it as a reference.

MHB

 

[DU99]

you could spend heaps of $$$$$'s on one..auto calibrate
http://australia.rs-online.com/web/search/...t&R=4427695

 

[Dazza_devil]

Here is the big problem, it was spot-on, you know that what you don't know is whether or not it's still spot-on, that's why we talk about "Calibration". That's the case with all mechanical and electronic thermometers; I don't want to harp on about this (there was another thread last couple of days) Get 1 decent glass laboratory thermometer and use it as a reference.

MHB

Apparently lab glass thermometers become inaccurate over time as well.
http://www.deltaenvironmental.com.au/manag...calibration.htm

 

[drsmurto]

Apparently lab glass thermometers become inaccurate over time as well.
http://www.deltaenvironmental.com.au/manag...calibration.htm

Yes, they can but it takes decades or a severe thermal shock (dunking it into liquid N2 has a tendency to kill them, as does 300+C oil).

I have a few mercury thermometers that i use to check the mash temp and alcohol based (0-50C range) for checking fridge temperatures for fermentation. I check the alcohol thermometers against the mercury thermometers on a regular basis.

As soon as one of the thermometers starts to drift i replace it.

One of the hardest parts of mash brewing is knowing what your mash temperature is and i see so many people who fail to properly calibrate their digital thermometers against accurate thermometers.

Calibrating a fridgemate/tempmate probe against another one and saying - "they read the same", is not calibrating it.

Expecting your fridgemate/tempmate to be accurate because it is brand new is naive.

 

[drtomc]

It seems to me that consistency is probably more important than [extreme] accuracy. As long as a thermometer/thermostat is consistent, you can experimentally adjust it to produce good results, just like you experimentally learn to work with other aspects of your gear to produce the results you want.

An analogous situation is ovens. When you get a new oven (or start using one in a new place, or whatever) you under or over bake your first few cakes until you learn what dial setting corresponds to "180C".

This doesn't mean we shouldn't desire accurate, but given the choice we should prefer consistent. Which just reinforces DrSmurto's practice of discarding thermometers once they begin to drift - they're no longer consistent.

T.

 

[katzke]

You want a certified thermometer. Need to learn how to take care of it before paying the price.

 

[davelovesbeer]

You could try these guys:

www.thermofisher.com.au

(no affiliation, just browsing their catalogue at work). They sell certified thermometers, that comes with a certificate and everything, ready for the scientific industry. I couldnt find the thermometers on the website - may have to ask for a catalogue - "Traceable Products Catalogue". I think prices started at about $25, but not sure about delivery prices.

View attachment thermometers.pdf

 

[Batz]

This is one of those things, check your thermometer against a master, is the master accurate? Check that against another master. is that correct?

Good luck

Batz

 

[manticle]

Hi All.

I have 3 thermometers and three big bloody head aches - which one can I trust?

Glass tube mercury - ~$30.
Ebay digital probe - ~$70.
3" dial mash master - ~$40.

In ice water they all read zero. In boiling water they all read 100. When I get to mash ranges though there are 1 - 2 - 3 degs discrepancies.

Does anyone know where I can get a thermometer that is certified to be accurate? Im willing to pay for the piece of mind.

I just want to have some conviction in my temps. Anyone else experiencing this?

I don't know what system you are running but I think A3k has a good point and it's where I would first look before just buying a new thermometer. My mash has hot spots and cool spots - i have to settle for a bit of an average - one reason I've started playing with stepped sacch rests.

My dial thermometer I don't even bother looking at anymore - waste of time and money and reads nothing remotely close to actual mash temp. Back of the esky is usually hotter than the front (manifold and tap draw heat away) regardless of stirring.

Have you tried measuring warm water and cold water with each to see if those discrepancies are still there? I find the only time my dial thermometer gives a good reading is in an esky full of water.

 

[bear09]

This is one of those things, check your thermometer against a master, is the master accurate? Check that against another master. is that correct?

Good luck

Batz

Yeah this is my exact problem. I need the master of the master of the master of thermometers....

 

[bear09]

I don't know what system you are running but I think A3k has a good point and it's where I would first look before just buying a new thermometer. My mash has hot spots and cool spots - i have to settle for a bit of an average - one reason I've started playing with stepped sacch rests.

My dial thermometer I don't even bother looking at anymore - waste of time and money and reads nothing remotely close to actual mash temp. Back of the esky is usually hotter than the front (manifold and tap draw heat away) regardless of stirring.

Have you tried measuring warm water and cold water with each to see if those discrepancies are still there? I find the only time my dial thermometer gives a good reading is in an esky full of water.

Hi Manticle.

I have tried warm and cold water and the discrepancy is still there. Like I said, at zero and 100 I am all good but anywhere in between and its out. I guess Ill just have to settle for close enough being good enough.

 

[felten]

I think Dr T is on the right track, as long as you're consistent, you can make any corrections via trial and error.

 

[katzke]

Hi Manticle.

I have tried warm and cold water and the discrepancy is still there. Like I said, at zero and 100 I am all good but anywhere in between and its out. I guess Ill just have to settle for close enough being good enough.

I would not brew with a mercury filled glass thermometer. Sorry I missed that the first time. If a spirit filled thermometer breaks in the brewery it is much easier to clean up.

A spirit filed glass thermometer, if taken care of in storage, will be more reliable then the digital or the dial. Both of those are subject to moisture as well as other issues unique to each type.

One thing to remember about glass thermometers is they are designed to work immersed to a certain point. That spot is usually marked with a line.

 

[newguy]

A wise man once said "A man with a thermometer knows the temperature. A man with two doesn't."

The discrepancies you're seeing are about right given that a mash usually isn't at a single uniform temperature and also taking into account the resolution and accuracy of the thermometers.

My advice is to:
- not use more than one thermometer simultaneously;
- don't worry about temperature differences unless they're really large (5 degrees or more); and
- save your money - don't bother with a new thermometer. If you do buy a new one you'll have 4 different readings and a few more grey hairs.

 

[pk.sax]

If you really want to check how far each thero is out between the extreme temps, do this simple cheap test to ge a general feel for it.

Getthe clinical thermo out, yes, the one you use to check fever thermometers. I hope you treat that one gently. Just measure the temperature of something at room temperature with that and with another thermometer at the same time. By no means conclusive but if a thermometer is real out that will let you pick it up far cheaper than another expensive thermometer. And learn to live with ranges. <there needs to be a smiley cor a shrug>

 

[drsmurto]

I would not brew with a mercury filled glass thermometer. Sorry I missed that the first time. If a spirit filled thermometer breaks in the brewery it is much easier to clean up.

A spirit filed glass thermometer, if taken care of in storage, will be more reliable then the digital or the dial. Both of those are subject to moisture as well as other issues unique to each type.

One thing to remember about glass thermometers is they are designed to work immersed to a certain point. That spot is usually marked with a line.

A mercury thermometer is IMO no more dangerous in a brewery than concentrated acids or bases (cleaners/sanitisers), boiling wort and naked flames.

The amount of mercury in a thermometer is very small and whilst highly toxic I'd much rather be cleaning up 1 broken thermometer than 1L of conc acid.

 

[Dazza_devil]

Don't forget parallax error and 1 degree scales on glass thermometers can also give reading variations.