Temperature drop during mash profile

[WM7793]

I have just completed a couple of small brews (11.5L) to gain experience of all grain brewing and Beersmith software, and now collating data to dial in my system.

I realise that this topic may have been posted elsewhere but it raises questions on Brewsmith.

The problem I have had on both brews is a sharp fall in mash tun temperature during a mash.

My equipment is a PID controlled 50L boiler, a 33L Coleman Extreme coolbox as a mashtun.

Additional information:
I do not have a sight glass fitted to the boiler so I am transferring the water 2L at a time to the coolbox.
The strike temperature given by Beersmith is 75.2 degrees C, followed by  2 batch sparges  at 75.2 degrees C which I diligently followed. (Mash profile added)
I preheated the coolbox with boiling water for 60 minutes prior to mashing.

Problem:
I measured the temperature at the end of 90 minutes mash and it was 56 degrees C (against a profile set by  Beersmith of 66 degrees C for 90 minutes).

I am losing  10 degrees C over this period !
I appreciate there is a lot of headroom in the coolbox during mashing and this is something I need to consider. (I purchased the Colemans 33L extreme coolbox as I understood that it had superior insulation.)

Questions:
1 The obvious solution is to raise the strike temperature.
(I have tried to change the strike temperature to a higher value to compensate for the loss of temperature in Beersmith (mash profile page) but this value seems to be fixed.)


Does anybody have any suggestions as to what I can do to either reduce temperature loss in the coolbox during the  mash period, or make alterations to Beersmith to compensate.

Best regards,
WM7793

[brewfun]

I'm just going to assume that with a nice rig like that, the mashtun lid is properly closed. 

How much water for preheat and what temperature is it after 60 minutes? If you're significantly cooler than 66C, then the next infusion will lose heat. With 10 liters, you should only need 5 to 10 minutes of preheat time, in my opinion. ...And the water just has to be hot (~75 - 80C), not boiling.

You seem to have the "adjust temp for equipment" button checked. Are the temperatures accurate? Your grain is really 22? Your mashtun temp is also 22C, which is far cooler than expected if you preheated.

Preheating should take specific heat out of the equation. But, it doesn't hurt to have it set accurately. Here's one method: http://www.beersmith.com/forum/index.php/topic,9324.0.html

[WM7793]

Thanks Brewfun for your reply.

As you can see, I am new to this and trying to dial my system in and not really knowing what all the options are in Beersmith yet!

To reply to your post, I did not think to actually measure the amount of preheat water into the mashtun, and also to measure the actual temperature too.

As for having the "adjust temp for equipment" button checked, I presumed that this was the correct thing to do?, not fully understanding what implications it may have.

Again, I have not checked on the temperature of the grain, nor the temperature of the mashtun. (back to inexperience of brewing and using the software)

I will certainly read your thread and update my mash profile.

Incidentally how do you measure the temperature of the mashtun, is this the ambient temperature without any liquid in?

Best regards,
WM7793

[brewfun]

As you can see, I am new to this and trying to dial my system in and not really knowing what all the options are in Beersmith yet!

I understand. Frankly, I don't know all there is to know about this program, either. Answering these questions is a chance to explore things that my brewing doesn't cover.

As for having the "adjust temp for equipment" button checked, I presumed that this was the correct thing to do?, not fully understanding what implications it may have.
...
Incidentally how do you measure the temperature of the mashtun, is this the ambient temperature without any liquid in?

"Adjust temp for equipment" takes into account the additional heat loss from these items. It's an option because not all systems or mashes need it. Personally, I have it set on and the temperature matches what I see at the point my grain and water is going into the mashtun.

I'd just use the ambient room temperature that the mash tun is stored in.

Often, brewers will make it a little more efficient by adding all their strike water at 5C or so hotter than they want to dough in. That preheats the mash tun as the water cools to where they want it for adding grain. No emptying required.

[WM7793]

Thanks again Brewfun for your prompt reply!

Using Beersmith is starting to come together now, thanks to everybody who has contributed to my earlier posts.

I will adjust temperatures in the mash profile for grain and mash tun temps, and will try your suggestion of adding the strike water a few degrees hotter prior to mashing in. I will also update my equipment profile on my next brew to reflect any changes to new measurements taken etc etc

Many thanks, and best regards,
WM7793

[Mtnmangh]

I almost always preheat my mash tun with boiling water and I have had to uncheck that box, because I have found that if I don't, my strike water is WAY too hot, leaving my mash about 5 degrees too hot.  I usually only lose 1-2 degrees F in an hour of mashing.

[RiverBrewer]

It is a real act of brutality to preheat a plastic cooler by putting boiling water into it! Strike temp water is more than adequate!

[brewfun]

+1 To what River Brewer said. It echoes what I said earlier in the thread.

Boiling water can severely warp the plastic, creating cracks that will let wort get into the insulation and fester. They're made for cold temperatures. With care, a plastic mash tun should last more than 100 batches.

[KernelCrush]

I never understood the need to preheat mashtuns, unless you enter the preheated value ( and grain temp ) in your 'mash' tab to arrive at your strike water temp.  brewfun has a post on how to determine your thermal mass.  I posted a while back how to do it in promash.  Follow the procedure once and you are set...till you get a new mashtun.  This method gets you within a degree..forever.

[mcbeer]

the higher the mass, the more energy it can store. the geometry of your mash tun coupled with the small size of your batch could cause trouble not only with heat sink but also with efficiency IMHO

[WM7793]

Thanks guys for all your input on this matter.

I am very much the wiser now!

Incidentally, Brewfun, I did not realise that the cool box mash tuns had a limited shelf life. In the UK they seem to be popular for the first time all grain brewers. Do the more experienced brewers migrate to insulated stainless steel mashtuns, or swap out their coolboxes?

I was surprised by how expensive the Colemans extreme 33L coolbox was (I got it for around £50 in the UK from Amazon, and I think I caught them on a good day, as they are currently £65)

I may take a look at other options in the future.

Best regards,
WM7793

[Scott Ickes]

In my brewclub, the coolers vs. insulated steel mashtuns tends to be about a 50/50 split.  I use two 48 quart rectangular coolers for mashtuns.  When one or both wear out, I'll probably stay with coolers and just purchase more.  The only way I see myself changing is if I can get my wife to agree to the expense of a RIMS or HERMS system.  But that is just dreaming on my part.

[tom_hampton]

I never understood the need to preheat mashtuns, unless you enter the preheated value ( and grain temp ) in your 'mash' tab to arrive at your strike water temp.  brewfun has a post on how to determine your thermal mass.  I posted a while back how to do it in promash.  Follow the procedure once and you are set...till you get a new mashtun.  This method gets you within a degree..forever.

Here's my process and rationale. 

1.  Have BS2 calculate strike temp without compensating for equipment temp.
2.  Heat strike water to strike temp + 10F.
3.  Transfer strike water to cooler MLT (48 qt. Cube).
4.  Allow MLT to stabilize.  Generally about strike + 5F.
5.  Add grain.  generally about mash temp + 2F.
6.  Stir until desired mash temp is achieved. 

Before you ask: Yes, I've calculated and measured the thermal mass of my equipment.  Yes, I can hit "within 2 degrees" of my desired mash temp using "compensate for equip temp" option. 

So, why? 

Because of the "within 2 degrees" qualifier.  That is a 4 degree variation in the mash temp depending on ambient conditions.  If I'm targetting 152, 154 isn't a huge difference.  But, if I get 150 on one batch and 154 on another...that IS a noticeable difference. 

So, I add enough heat to the process to guarantee that I'm on the high side, and can drop the temp simply by stirring.  Then my mash temp is dead on.  It takes me about 15 seconds of stirring to drop my mash by 1 degree. 

The alternative is to add more hot (boiling) water if I'm low (or decoct).  Both alternatives take significantly more than 60 seconds unless I have a second burner of boiling water.  Also, both processes have some impact on consistency (mash thickness variation --- not a big deal, melanoidin formation---a noticeable effect). 

[KernelCrush]

Tom, Good to see you posting again.  We all spend frustrating days trying to dial in mash temp on our equipment..to the point you are afraid to change anything once you do.    At 8/9 gallons and 20 something pounds of grain I never had much luck correcting if needed.  Took too much water to rise and/or cool down and stirring at this volume takes a long time, time I normally spend checking pH, measuring additions, etc.  When I stumbled on the method mentioned above I spent one day boiling water like I was brewing beer, recording temps, deadspace, etc.  It gets me within the width of my thermometer dial, usually less.  Its a good day when that problem gets solved.

[tom_hampton]

Tom, Good to see you posting again.  We all spend frustrating days trying to dial in mash temp on our equipment..to the point you are afraid to change anything once you do.    At 8/9 gallons and 20 something pounds of grain I never had much luck correcting if needed.  Took too much water to rise and/or cool down and stirring at this volume takes a long time, time I normally spend checking pH, measuring additions, etc.  When I stumbled on the method mentioned above I spent one day boiling water like I was brewing beer, recording temps, deadspace, etc.  It gets me within the width of my thermometer dial, usually less.  Its a good day when that problem gets solved.

Yes, I can see your problem with the larger batch size.  A side benefit of the larger batch size is the decreased effect of ambient conditions.  Your surface area to mass ratio is quite a bit lower than for a 5 gallon batch.  That helps to explain why you see a 1 degree variation, whereas I see 2 when following the "adjust for equipment temperature approach". 

One of my tricks for quickly dropping the temperature is to recirculate with a 1 gallon pitcher.  I can VERY quickly drop several degrees.  I've had a couple instances where something went wrong in BS2 and I ended up with a wildly unreasonable strike temperature which I trusted blindly.  At dough-in I was like 10 degrees high--in the 160s.  drain and pour from high, allowing the stream to pass through the air removed a lot of heat very quickly.