Mash Tun Heat Capacity - confusion
Mash Tun Heat Capacity - confusion
I've used the tun calibration somewhat successfully for hitting the neighborhood of my mash temperature, but have blamed any low mash temperatures on my low brewing environment temperature.
Now, I'm making a batch with a very small grain bill and a very specific mash temperature I want to hit. For these reasons, I intend to mash by adding grain to water that has preheated my tun and stabilized at my strike temperature.
So, I want to circumvent my heat capacity calculations. I did this by ceating a new vessel, giving it all the same dimensions as my other tun, but leaving the heat capacity at "0".
Here's the problem:
The tun with a positive heat capacity gives me a lower strike water temperature than the tun with no heat capacity (for the same grain, volume, and mash temp settings).
Am I confused, or is this backwards?
Now, I'm making a batch with a very small grain bill and a very specific mash temperature I want to hit. For these reasons, I intend to mash by adding grain to water that has preheated my tun and stabilized at my strike temperature.
So, I want to circumvent my heat capacity calculations. I did this by ceating a new vessel, giving it all the same dimensions as my other tun, but leaving the heat capacity at "0".
Here's the problem:
The tun with a positive heat capacity gives me a lower strike water temperature than the tun with no heat capacity (for the same grain, volume, and mash temp settings).
Am I confused, or is this backwards?
BTP v2.0.* Windows XP
Re: Mash Tun Heat Capacity - confusion
The strike water temperature is lower because the system that includes heat capacity from the vessel has a greater capacity to store heat than the system that has water alone. Without the added heat absorbed by the vessel factored in, the heat capacity of the water by itself is what is used to raise the temperature of the grist.slothrob wrote:The tun with a positive heat capacity gives me a lower strike water temperature than the tun with no heat capacity (for the same grain, volume, and mash temp settings).
Am I confused, or is this backwards?
Jeff
BeerTools.com Staff
BeerTools.com Staff
I thought the formula would have been designed to work in the opposite direction. i.e., when adding water to a tun with heat capacity, some heat will be absorbed by the tun. If the tun has no heat capacity, then the water would lose no heat to the tun.
So your formula is actually designed to work in a system where the water is already in the tun and stabilized (at the predicted strike temperature), to which the grain is then added, NOT a system where water (at the strike temperature) is added to a room temperature tun holding room temperature grain, correct?
So your formula is actually designed to work in a system where the water is already in the tun and stabilized (at the predicted strike temperature), to which the grain is then added, NOT a system where water (at the strike temperature) is added to a room temperature tun holding room temperature grain, correct?
BTP v2.0.* Windows XP
That depends on whether you have selected a heating vessel or not. If you select a heating vessel then BTP assumes that the water is heated and then added to the mash vessel. If no heating vessel is selected, then BTP assumes that the water is heated in the mash vessel. Does there seem to be an error in the calculations?slothrob wrote:So your formula is actually designed to work in a system where the water is already in the tun and stabilized (at the predicted strike temperature), to which the grain is then added, NOT a system where water (at the strike temperature) is added to a room temperature tun holding room temperature grain, correct?
Jeff
BeerTools.com Staff
BeerTools.com Staff
OMG... all my numbers in BTP have been pretty perfect except for strike temps... I have had to offset a little bit to hit them, and I could never figure out why. I had always figured it was because of my crappy mash tun.jeff wrote:... If no heating vessel is selected, then BTP assumes that the water is heated in the mash vessel...
This explains it. I do not have a kettle selected, yet, i do fill a cooler type mash tun. I reconfigured some of my older schedules... and voila, this is where the discrepency is.
I see this documented in the wiki... but it is not mentioned as a "must do" type of thing...
well, on my next brew, we will see if i can hit my numbers without overdriving the strike temp.
Fermenting : Ordinary Bitter, Hefe
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
I'll have to double check and let you know, but I'm pretty sure I made the same mistake as bxwrxbz. I assumed that since I wasn't heating the MASH, I didn't need a heating vessel, while I should have done the opposite. At the very least, I haven't been paying attention to wether I had a heating vessel specified, or not.jeff wrote:That depends on whether you have selected a heating vessel or not. If you select a heating vessel then BTP assumes that the water is heated and then added to the mash vessel. If no heating vessel is selected, then BTP assumes that the water is heated in the mash vessel. Does there seem to be an error in the calculations?
I've been using the same kind of fudge factor, thinking my low room temperature was throwing off the calculations.bzwrxbz wrote:OMG... all my numbers in BTP have been pretty perfect except for strike temps... I have had to offset a little bit to hit them, and I could never figure out why. I had always figured it was because of my crappy mash tun.
Well, on my next brew, we will see if i can hit my numbers without overdriving the strike temp.
I'll get to check it when I skive work tomorrow for a session. Only thing is, I'm doing a step mash tomorrow, which I don't normally do, so it won't be a perfect test of my previous calculations.
BTP v2.0.* Windows XP
omg, now i know why i was always low on my mash in. It also explains why there was a difference between the values i got from beersmith and btp.
can someone do a basic tutorial to help new/other users?
later,
jaw
can someone do a basic tutorial to help new/other users?
later,
jaw
iMac 27", 3.4 GHz Intel Core i5, 8GB Ram, Mac OSX 10.12.6
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Wiki Addition on "Mash In"
I have modified the "Mash In" portion of the wiki to reflect what Jeff has said above. I pasted a couple of sentences from his above post, and added one myself.
here-> http://www.beertoolspro.com/wiki/Mash_In
anyone can feel free to add or modify it...
cheers!
here-> http://www.beertoolspro.com/wiki/Mash_In
anyone can feel free to add or modify it...
cheers!
Fermenting : Ordinary Bitter, Hefe
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
Checkbox Suggestion
I suggest a checkbox be added to the "Mash In" popup that toggles the following->
x Direct Fired Mashtun
When it is checked, the "Heating Vessel" dropdown becomes disabled, or disappears, so it becomes obvious what is going on.
When it is not checked, the "Heating Vessel" dropdown becomes active, so the user can select the appropriate equipment...
just my 2 cents
cheers!
x Direct Fired Mashtun
When it is checked, the "Heating Vessel" dropdown becomes disabled, or disappears, so it becomes obvious what is going on.
When it is not checked, the "Heating Vessel" dropdown becomes active, so the user can select the appropriate equipment...
just my 2 cents
cheers!
Fermenting : Ordinary Bitter, Hefe
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
Bottled : Too many bottles
WinXP PentiumIV Res:1920x1200 120DPI
Blog: http://hobbybrau.blogspot.com
also is there anyway of making the sparge steps a little more intuitive. I hate having to zero my residual. I would sooner have something to select that would automatically calc that i'm going to drain the whole tun.
iMac 27", 3.4 GHz Intel Core i5, 8GB Ram, Mac OSX 10.12.6
iPhone 7+
iPad Pro 10.5
I like macs
iPhone 7+
iPad Pro 10.5
I like macs