Igloo Vs. Rubbermaid thermal test.

[fosgate]

Posting this for people who are looking at Mash Tun/HLT coolers. Hope it helps someone. I just got my Mash Tun setup in an Igloo 10 gal Commercial grade cooler and modified it by drilling a 1/2in hole to run tubing for my sparge through the lid.

and also bought a clearance Rubbermaid 5 gal cooler at my local Menards Hardware for $12.

I had to clean them out and test to make sure there were no leaks. However, after struggling with a cooler at the Lab in my brewing class I decided to do a side by side comparison for being able to maintain temp. The mash tun (cooler, a no name 5gal) I used in class would loose about 6 degrees C (10.8F) every thirty minutes with a cooler in the lab and would have to check and add hot liquer every 30 min to the mash. Needless to say the efficiency of that setup really sucks and takes about 1/4th more grain than a recipe calling for 70% efficiency.

Since I don't know the heat absorption rating of either cooler I used the scientific method of guessing by using the absorption rate of Styrofoam and the mass of each container to come up with my needed volume of water. I filled up the 10gal tank with about 5 gallons of hot tap water and put about 3.5 gallons in the smaller tank. I let them both sit for at least 5 minutes with the hot water before taking the initial reading to let heat absorption take place (note the smaller cooler has a higher temp due to less mass of the cooler to absorb the initial heat). Here are the results over 60minutes.

Igloo 10Gal Commercial Grade $64 before mods
T-0=56C (132.8f)
T-60=55C (131f)

Rubbermaid $12 no mods
T-59C (138.2f)
T-60=57C (134.6f)


Just thought I would post these for people looking at coolers. There is a slight difference between these two but the major is the no name brand cooler I use at a lab with 6 degrees C (10.8F) every 30 minutes. So yes there is a difference in coolers but I think either the Rubbermaid or the Igloo would be great for a Mash Tun or a HLT. The Rubbermaid is very cost efficient but the Igloo Commercial grade is the best I have seen.

With both it is important to know of course what temp the water going in them needs to be. You can either use this:

Q = mc ΔT
or
Q = mc (Tf-Ti)

Q: Energy {flow} Joules
m: mass, kg *remember that 1 mL = 1 g
c: specific heat capacity J/(kg°C)

there are many different specific heat capacities for many different substances)
water has a SHC of 4.18 and ice has 2.01, try and find a table for other substances
ΔT = the change in temperature (always the highest temp minus the lowest)
(T2-T1) (ex/ 32-12 = 20)


Here are some Specific Heat Capacity of material in brewing.
Substance Specific Heat (J/kg °C)
Alcohol 2430
Water 4186
Lead 130
Silver 230
Aluminum 900
Ice 2200
Iron 460
Styrofoam 1300

I always assume that the specific heat of grain is 0.4 kJ/(kg°C)

Useful conversions:
Density of water 1000kg/m3
1 lb =2.2 kg
1 cubic meter = 264 US gallons
°C x 9/5 + 32 = °F. (°F - 32) x 5/9 = °C



Alternately if you don't like doing math you can just put a couple cups of boiling water in your cooler a few minutes before use to preheat them and just RDWHAHB.

 

[Hex23]

Thanks for the post. Really useful information. I think many months ago I looked online and did some experiments to determine the specific heat of my Home Depot branded Rubbermaid mash tun. I plugged those numbers into BeerSmith so that it can calculate a strike water temp. Then after mashing a few batches, I found that I would consistently be 1-2 degrees less than my intended initial mash temp, so I learned to just increase the strike water temp by about 2 degrees.

What I'd really like to know is whether there's much difference between these two brands in terms of long term heat/cool warping. My rubbermaid has one large warp in it. Not cracked (yet), but looks like it would over time.

 

[fosgate]

There is a difference between the commercial line of the Igloo and the standard Rubbermaid. The igloo you can tell feels more like a solid tube of heavier composite material than the Rubbermaid which has a bit bulky in comparison. I have been around the Igloo commercial line since I was a kid in the 70's with similar drink coolers playing little league baseball and never saw one with a damaged inner sleeve. Seen one sliced or cracked on the outside once years ago.

 

[FATC1TY]

Thanks for the post. Really useful information. I think many months ago I looked online and did some experiments to determine the specific heat of my Home Depot branded Rubbermaid mash tun. I plugged those numbers into BeerSmith so that it can calculate a strike water temp. Then after mashing a few batches, I found that I would consistently be 1-2 degrees less than my intended initial mash temp, so I learned to just increase the strike water temp by about 2 degrees.

What I'd really like to know is whether there's much difference between these two brands in terms of long term heat/cool warping. My rubbermaid has one large warp in it. Not cracked (yet), but looks like it would over time.

My rubbermaid actually ends up hotter than intended in Beersmith, so I've dropped my strike temp as I just don't lose the intended heat. If I follow it, and I hit it right, it's warmer than I need and I have to stir and leave it open to get it down.

I have a lab calibration thermometer and a Thermapen that both read identical as well, so I know I'm working with consistent numbers. I think it has a bit to do with climate as well, as from cooler to cooler.

 

[Hex23]

My rubbermaid actually ends up hotter than intended in Beersmith, so I've dropped my strike temp as I just don't lose the intended heat. If I follow it, and I hit it right, it's warmer than I need and I have to stir and leave it open to get it down.

I have a lab calibration thermometer and a Thermapen that both read identical as well, so I know I'm working with consistent numbers. I think it has a bit to do with climate as well, as from cooler to cooler.

For my 10 gallon mash tun, I have a weight of 7.4 lbs, and specific heat of 0.30 CAL/gram-deg C.

One other thing that I've considered is that the water just loses heat as I transfer it from the MLT to the MT. I am using a 1-gallon pitcher and I'm sure the action of pouring it has some heat-loss effect.

 

[fosgate]

I have the same problem Hex. Doesn't seem like much but these little things add up and is my next thing I'm looking into for my setup. I currently use high temp 3/8 ID silicone tubing but I think I'm going to try switching to a Poly Tubing and wrap it with insulation to see if that helps heat retention to allow longer sparge times. I considered another kettle and burner for a HLT until I just saw this Rubbermaid sitting there so cheap. I have my sparge coil self contained in the Mash Tun so I don't have to worry about opening up the cooler and loosing heat while sparging. If I can figure out a good insulator to retain heat and let me sparge slowly for 40min to an hour without more than a degree or two of heat loss during the time, I think I should be able to really crank up my efficiency.

 

[FATC1TY]

I have the same problem Hex. Doesn't seem like much but these little things add up and is my next thing I'm looking into for my setup. I currently use high temp 3/8 ID silicone tubing but I think I'm going to try switching to a Poly Tubing and wrap it with insulation to see if that helps heat retention to allow longer sparge times. I considered another kettle and burner for a HLT until I just saw this Rubbermaid sitting there so cheap. I have my sparge coil self contained in the Mash Tun so I don't have to worry about opening up the cooler and loosing heat while sparging. If I can figure out a good insulator to retain heat and let me sparge slowly for 40min to an hour without more than a degree or two of heat loss during the time, I think I should be able to really crank up my efficiency.

You could also be really over analyzing it, unless thats your thing.

I lose less than 2 degrees max on my mash, and thats opening it twice to stir in 60 minutes. Once at 30, and another 10 minutes before I sparge, especially if it's a large grain bill over 19 lbs.

Sparging wise, I don't care. I heat it up to 175, and let it go and pour it in with the pitcher, and hit the temps.

Sparging temp isn't really super, super important. Higher temp allows the sugars to flow slightly better, but a good stir goes a long way for batch sparging.

If you fly sparge, then I could see it helping a bit more, but thats really just chasing numbers at that point.

 

[fosgate]

Fatcity, I'm analyzing what need as this is my initial setup for home. As stated above I have been involved in a brewing course. It is very intensive with chemistry, biology, physics, history etc. While I am in the class 8hrs a week I am putting in nearly another 20hrs of study time outside of the class. Sorry if I am overly detailed as I have much more strict standards I must abide by. Wishing I would have taken this class the first time I attempted college 20+yrs ago. What's cool about the class is with a dozen of us brewing a batch every week and recording the details of the variations of using the same recipe, ingredients, equipment. We get to taste the difference in what preparation details make. Fortunately I have not made a bad beer yet, but I have tasted a few bad ones. Kind of amazing what a few degrees will make in the end product.

 

[FATC1TY]

Fatcity, I'm analyzing what need as this is my initial setup for home. As stated above I have been involved in a brewing course. It is very intensive with chemistry, biology, physics, history etc. While I am in the class 8hrs a week I am putting in nearly another 20hrs of study time outside of the class. Sorry if I am overly detailed as I have much more strict standards I must abide by. Wishing I would have taken this class the first time I attempted college 20+yrs ago. What's cool about the class is with a dozen of us brewing a batch every week and recording the details of the variations of using the same recipe, ingredients, equipment. We get to taste the difference in what preparation details make. Fortunately I have not made a bad beer yet, but I have tasted a few bad ones. Kind of amazing what a few degrees will make in the end product.

Oh, by all means, carry on. I really appreciate the in depth review of the heat loss of your mash tun. I'm a Chemist by trade, and completely understand the over analytical nature of people, myself included.

I was simple just stating that this is probably not the case for all the coolers out there. Mine actually doesn't lose that much heat at all. I find like both stated, that I can loose heat from simply pulling the water out from the HLT to the tun, or from my kettle heating water, to my HLT.

Good luck with your brewing class, by the way!

 

[fosgate]

Thanks! Figured it would be a cake class to finish my Public Health minor but has been one of my more demanding classes. Funny you should mention your a chemist. I have five professors teaching this class and they all brew at home, couple of them for over 30yrs each. Three are biochemists, one teaches history and the last teaches physics. They'll go into extensive detail and expect us to know the great detail but then remind us when we are brewing the scientific method of guessing and RDWHAHB goes a long way. After all there are people who chew grain and spit into the beer for the enzymes and they make beer. (Not one I would like to try) The give us leeway when it comes to conducting our experiments but we must record every detail and we discuss results with one of the five profs. I was just astonished a couple times when we got the thumbs up "close enough". Just wish the college would have gotten us a little better equip, our coolers loosing 12C per hour is pretty ridiculous when trying to brew from.