15L "water" heated mash-tun

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Demy
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15L "water" heated mash-tun

Post by Demy » Fri Feb 19, 2021 8:37 am

I wanted your opinion from you bad boys!
Clarification: I already run a steam jacket and I'm thrilled with it, I think it's a very versatile system.
In this case, let's talk about my little mash-tun (mainly for homebrewing) of only 15 liters. I currently use it with a 1500w hot plate and it works very well (no burns) combined with a mixer with a small 12v motor. The only problem is that it is a bit slow to heat up. I thought of a small jacket but there is already a tap and a thermowell so I thought of a similar system but only on the bottom of the pot. I ask the guys that more experienced, will I have an advantage in terms of heating speed or is there a risk that the 2 systems are very similar?
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BlackStrap
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Re: 15L "water" heated mash-tun

Post by BlackStrap » Sat Feb 20, 2021 2:55 am

Hey there Demy;

Interesting concept, I don't believe you will heat things up faster, in fact I believe it would be slower... These are just some of my thoughts, and I'm not real technical. If I'm understand you right...you want to but your 15L boiler on top of a hot water tank that has a 1500w element in it. Basically creating a heat plate that is filled with water?

Water will only reach a point of boiling, the boiling points can be raised by pressure, or chemicals (then there's those safety issues) Now you could fill the tank with something like vegetable oil, Corn oil has a smoke point of 455F and a flash point of 617F and a fire point of 670F (Those numbers vary depending on the type of oil used)

However the liquid filled hot plate will not get much hotter than those numbers even under pressure. Where as the electric hot plate will reach much higher temps and at a faster rate.

Again, just my thoughts, and I'm hoping someone will jump in here, and give you a more technical answer.

Be Safe, and have Fun!
BlackStrap
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Demy
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Re: 15L "water" heated mash-tun

Post by Demy » Sat Feb 20, 2021 1:35 pm

BlackStrap wrote:
Sat Feb 20, 2021 2:55 am
Hey there Demy;

Interesting concept, I don't believe you will heat things up faster, in fact I believe it would be slower... These are just some of my thoughts, and I'm not real technical. If I'm understand you right...you want to but your 15L boiler on top of a hot water tank that has a 1500w element in it. Basically creating a heat plate that is filled with water?

Water will only reach a point of boiling, the boiling points can be raised by pressure, or chemicals (then there's those safety issues) Now you could fill the tank with something like vegetable oil, Corn oil has a smoke point of 455F and a flash point of 617F and a fire point of 670F (Those numbers vary depending on the type of oil used)

However the liquid filled hot plate will not get much hotter than those numbers even under pressure. Where as the electric hot plate will reach much higher temps and at a faster rate.

Again, just my thoughts, and I'm hoping someone will jump in here, and give you a more technical answer.

Be Safe, and have Fun!
BlackStrap
Thank you very much for the intervention. I already have a vapor jacket and it works really well and wanted to apply something similar to the mash-tun. I had some doubts about its functioning too.

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NZChris
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Re: 15L "water" heated mash-tun

Post by NZChris » Sat Feb 20, 2021 10:48 pm

The rate of heat transfer you get is dependent on the temperature difference. I use a bain-marie for making cheese and can tell you that they are a PITA when you are in a hurry, the temperatures are close and you don't want to overshoot your target.

When I need to get the temperature up quickly, I have to have the bath temperature high until the milk reaches the target, then quickly reduce the temperature of the bath to the target by replacing enough of the hot water with cold water. Bear in mind that I'm only aiming for 32C, which is a lot lower than you need to get to.

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Demy
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Re: 15L "water" heated mash-tun

Post by Demy » Sun Feb 21, 2021 1:40 am

NZChris wrote:
Sat Feb 20, 2021 10:48 pm
The rate of heat transfer you get is dependent on the temperature difference. I use a bain-marie for making cheese and can tell you that they are a PITA when you are in a hurry, the temperatures are close and you don't want to overshoot your target.

When I need to get the temperature up quickly, I have to have the bath temperature high until the milk reaches the target, then quickly reduce the temperature of the bath to the target by replacing enough of the hot water with cold water. Bear in mind that I'm only aiming for 32C, which is a lot lower than you need to get to.
Thank you very much, confirm my suspicion. Actually, by heating only the bottom, I think you have an even smaller transfer. Maybe a whole jacket (like in my still) would make more sense since the heat transfer takes place via steam, what do you say? Ultimately my problem is just a low heat-up rate but I'd be fine with that too.

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