15L "water" heated mash-tun

Any hardware used for mashing, fermenting or aging.

Moderator: Site Moderator

Post Reply
User avatar
Demy
Master of Distillation
Posts: 3084
Joined: Fri Sep 04, 2020 1:45 pm

15L "water" heated mash-tun

Post by Demy »

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?
Immagine.png
Immagine.png (13.47 KiB) Viewed 927 times
User avatar
BlackStrap
Swill Maker
Posts: 301
Joined: Thu Mar 02, 2017 3:48 pm
Location: The hills of Appalachia

Re: 15L "water" heated mash-tun

Post by BlackStrap »

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
Most questions can be answered here http://homedistiller.org/ and here http://homedistiller.org/forum/viewforum.php?f=46

The one who cuts the firewood gets twice the warmth
User avatar
Demy
Master of Distillation
Posts: 3084
Joined: Fri Sep 04, 2020 1:45 pm

Re: 15L "water" heated mash-tun

Post by Demy »

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.
User avatar
NZChris
Master of Distillation
Posts: 13062
Joined: Tue Apr 23, 2013 2:42 am
Location: New Zealand

Re: 15L "water" heated mash-tun

Post by NZChris »

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.
User avatar
Demy
Master of Distillation
Posts: 3084
Joined: Fri Sep 04, 2020 1:45 pm

Re: 15L "water" heated mash-tun

Post by Demy »

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.
User avatar
subbrew
Site Donor
Site Donor
Posts: 1275
Joined: Thu Jan 21, 2021 1:40 pm
Location: West of the Mississippi

Re: 15L "water" heated mash-tun

Post by subbrew »

If I understand correctly you would just be setting your mash tun on a hot water bath, atmospheric pressure. That is very different heat transfer than a steam jacket. In a water bath the heat transfer is via conduction and the rate is dependent on the temp differences between the bath and what you are heating, in this case mash. so ever if your water is at boiling (212 at sea level, 202 where I live) as your mash tun heats up the temp delta will decrease and the rate your mash temp increases will decrease as well. With the hot plate there is a much larger delta so directly on the hot plate would be faster.

In the case of a steam jacket you are counting on the heat of vaporization. When that steam condenses on the side of your boiler each gram of water vapor has to lose 100 calories of energy. that energy goes into the boiler. In a water bath if a gram of water in the bath gives up one degree of heat (for the engineers I know a degree is not an energy unit of measurement but it does reflect energy content) to the water in the mash tun that is only 1 calorie transferred. That is why steam works so well but also why it can burn so fast. And that is talking wet steam, you move to dry, super-heated steam and you have a different animal all together as far as energy is concerned.
User avatar
Demy
Master of Distillation
Posts: 3084
Joined: Fri Sep 04, 2020 1:45 pm

Re: 15L "water" heated mash-tun

Post by Demy »

subbrew wrote: Fri Feb 26, 2021 9:59 am If I understand correctly you would just be setting your mash tun on a hot water bath, atmospheric pressure. That is very different heat transfer than a steam jacket. In a water bath the heat transfer is via conduction and the rate is dependent on the temp differences between the bath and what you are heating, in this case mash. so ever if your water is at boiling (212 at sea level, 202 where I live) as your mash tun heats up the temp delta will decrease and the rate your mash temp increases will decrease as well. With the hot plate there is a much larger delta so directly on the hot plate would be faster.

In the case of a steam jacket you are counting on the heat of vaporization. When that steam condenses on the side of your boiler each gram of water vapor has to lose 100 calories of energy. that energy goes into the boiler. In a water bath if a gram of water in the bath gives up one degree of heat (for the engineers I know a degree is not an energy unit of measurement but it does reflect energy content) to the water in the mash tun that is only 1 calorie transferred. That is why steam works so well but also why it can burn so fast. And that is talking wet steam, you move to dry, super-heated steam and you have a different animal all together as far as energy is concerned.
In reality it would be a sealed container with a safety valve like in a jacket but the steam would only hit the bottom. I know the limitations of the water bath and it wouldn't do. But you're right, I realize that it is not clear from the drawing even though I wrote that there is a valve
Immagine.png
Immagine.png (7.48 KiB) Viewed 815 times
User avatar
subbrew
Site Donor
Site Donor
Posts: 1275
Joined: Thu Jan 21, 2021 1:40 pm
Location: West of the Mississippi

Re: 15L "water" heated mash-tun

Post by subbrew »

thank you for the clarification. Still do not think it will be faster because you are using the same energy input, 1500 watt, and now have to also heat the extra mass. But that may be wrong as heating directly on an element there is heat lost that does not go into the tun by going down or out the sides. With an immersed element all the heat goes into the fluid. And once the water is boiling should be pretty much 100% of energy going from element to water vapor to tun via condensation, especially if you insulate the "boiler" part.
User avatar
Demy
Master of Distillation
Posts: 3084
Joined: Fri Sep 04, 2020 1:45 pm

Re: 15L "water" heated mash-tun

Post by Demy »

subbrew wrote: Fri Feb 26, 2021 12:54 pm thank you for the clarification. Still do not think it will be faster because you are using the same energy input, 1500 watt, and now have to also heat the extra mass. But that may be wrong as heating directly on an element there is heat lost that does not go into the tun by going down or out the sides. With an immersed element all the heat goes into the fluid. And once the water is boiling should be pretty much 100% of energy going from element to water vapor to tun via condensation, especially if you insulate the "boiler" part.
The same doubts that I had and that brought me here. My steam jacket works great but there is more contact surface. With my little mash tun it would only be worth it if it increased the heating rate.
Post Reply