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Aschecte 09-27-2012 01:12 PM

Another BeerSmith question about specific heat
 
Hopefully someone can help me with this.... I am running beersmith 2 and after quite sometime ignoring the strike temps and infusion temps thta Beersmith gives as they are always extrememly off I decided to do some research as it''s annoying this feature does not get uses. I have pretty much narrowed it down to the specific heat of my MLT ( a Igloo 10 gallon round cooler ). Originally I left it at the default .3 SH beersmith reccomends. Now for a practical example.... MLT # = 12lbs, MLT temp- 72deg, grain temp 72deg grain# 10.5lbs, desired mash temp 152 deg. Beersmith would have me add 14.65qts at 165 degrees this is even with the adjust for equipment turned on. I would end up with a mash temp of like 145deg and either had to decoct the mash or add boiling water and really thin out the mash. Now after playing around and doing about 3 hours of research I changed my specific heat to .98 !!!! has anyone else had to deviate from beersmith's reccomendation this much ? I mean that's a huge difference from .3 specific heat for plastic. Now for that practical application all the info above stays the same but then my mash after adding the strike water is a perfect 152 deg and once the mash hits temp and everything equalizes I loose less than 1 degree over the hour. Basically what I'm asking is did I change this right by changing my specific heat or is there a better way to hit my strike temp and is a .98 specific heat for the above cooler correct / normal ? Thanks for any input.

:mug:

EvilDeadAsh 09-27-2012 01:20 PM

Just throwing out a curveball here - what is your mash tun weight set to? I would assume if the weight isn't set properly for your mash tun, BS doesn't have enough information to make more accurate calculations.

Bear419 09-27-2012 01:28 PM

I had a similar issue. BS recommends the .3 for plastic I think, but the igloo cooler is plastic AND insulation so you aren't gong to get the right answer by just keying in weight of the cooler. I don't remember the exact numbers but if you do a search you can find the mash tun weights other have used to "trick" BS into giving the right strike temp for an igloo cooler.

IMHO, it is just easier to preheat the tun or add the strike water first and add the grains once the water stabilizes at the right temp.

Aschecte 09-27-2012 01:29 PM

Quote:

Originally Posted by EvilDeadAsh (Post 4448881)
Just throwing out a curveball here - what is your mash tun weight set to? I would assume if the weight isn't set properly for your mash tun, BS doesn't have enough information to make more accurate calculations.

That is a good idea but my weight is set propely I have a very accurate scale and when I first bought BS2 I weighed the mash tun and entered the weight. I also measured my deadspace which I have always thought that meant the amount of liquid below the false bottom and is not picked up by the drain which is a .25 gallon. I may though have to adjust the MLT temp and grain temp every time I brew as those variable could change based upon ambient temps they are stored at. But my specific heat should not change that much even with all the variables I just mentioned.

Aschecte 09-28-2012 01:03 AM

Bump

brewtus_ 09-28-2012 01:45 AM

Is your mash tun volme set correctly?

ArcaneXor 09-28-2012 01:45 AM

I had to adjust the weight down for mine because my mash temps came in high. Works like a charm now.

Aschecte 09-28-2012 02:01 AM

Quote:

Originally Posted by brewtus_ (Post 4451062)
Is your mash tun volme set correctly?

On the verge of sounding dumb I have it set at 10 gallons for the volume as it is a 10 gallon cooler. That is correct right ?

Aschecte 09-28-2012 02:02 AM

Quote:

Originally Posted by ArcaneXor (Post 4451064)
I had to adjust the weight down for mine because my mash temps came in high. Works like a charm now.

Yeah I have the exact opposite it is coming in low.

brewtus_ 09-28-2012 02:19 AM

Quote:

Originally Posted by Aschecte (Post 4451109)
On the verge of sounding dumb I have it set at 10 gallons for the volume as it is a 10 gallon cooler. That is correct right ?

Not sure. I've got a Rubbermaid 7 gallon cooler that I set to 7 gallons and kept the heat capacity at 0.30, and as long as I set my starting temps (grain, cooler, etc.) at the actual temps on brew days, I get +/- 0.5F actual measured temps vs theoretical temps every time.

I'm a bit confused at why you're seeing what you're seeing. Usually the BS2 calculations are spot on. I always hated thermodynamics.


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