Quantcast

MLT Losing Heat?

HomeBrewTalk.com - Beer, Wine, Mead, & Cider Brewing Discussion Community.

Help Support Homebrew Talk:

Pelikan

Well-Known Member
Joined
Oct 19, 2008
Messages
901
Reaction score
13
Location
Q Continuum
I just converted a cooler a few batches back, and all things considered it's working rather well. Getting a consistent 75%-80% efficiency, depending upon the amount/type of grain.

That aside, I noticed I'm losing a little bit of heat over the course of the mash. It'll hold constant for the first 30-40 minutes, then I'll lose about 1 to 2 degrees from that point until the end.

For example, if it's a 154*F mash, it'll hold steady for the first 30 minutes. Then it'll drop to 153*F, then down to 152 from about 15 minutes remaining until the end. Normal, or should I start looking into solutions?
 

jagg

Well-Known Member
Joined
Nov 30, 2006
Messages
520
Reaction score
2
Location
North Central NC
I just converted a cooler a few batches back, and all things considered it's working rather well. Getting a consistent 75%-80% efficiency, depending upon the amount/type of grain.

That aside, I noticed I'm losing a little bit of heat over the course of the mash. It'll hold constant for the first 30-40 minutes, then I'll lose about 1 to 2 degrees from that point until the end.

For example, if it's a 154*F mash, it'll hold steady for the first 30 minutes. Then it'll drop to 153*F, then down to 152 from about 15 minutes remaining until the end. Normal, or should I start looking into solutions?
That is pretty normal for a cooler to lose 1-3 degrees over the hour mash, most, if not all conversion will be complete after 30 min. anyway, assuming you are preheating the mash tun, I wouldnt worry at all, brew on:mug:
 

flyangler18

Well-Known Member
Joined
Jun 5, 2008
Messages
5,559
Reaction score
43
Location
Hanover, PA
1-2 degrees over the course of an hour with a cooler MLT is within normal operating parameters, in my experience, particularly with smallish grain bills where there may be a sizeable headspace unoccupied by the volume of the mash.

One of the best ways to keep temperature constant is by minimizing the headspace, using thermal mass to maintain temp. A piece of closed foam insulation floated on the surface of the mash will keep temp very stable.

Also, preheat your MLT with 175-180° water and allow it to drop to your desired strike temp before dough in. Otherwise, the cooler will suck away major heat and you'll miss your strike temp and continue to lose heat over the hour-long rest.
 

Runyanka

Well-Known Member
Joined
Dec 31, 2008
Messages
1,544
Reaction score
20
Location
Frisco
As stated above, make sure your MLT is fully pre-heated prior to doughing in, this will dramatically affect the overall temps. :rockin:
 

ChemE

Well-Known Member
Joined
Mar 3, 2008
Messages
596
Reaction score
20
Location
Columbia, SC
Or if you're using Beer Smith, just weigh your MLT and enter the weight and material of the MLT into Beer Smith and have it adjust the temperature of your strike water to compensate. I just did my first single infusion with mashout today (had been doing double decoctions up to this point) and BS nailed my strike and mashout temps since it knows how heavy my MLT is.

Oh I almost forgot to mention, I mashed in at 157F and didn't drop a single degree across 45 minutes. Wrapping the MLT in the blanket and shooting the lid full of foam help tremendously.
 

HopHeadWeb

Member
Joined
Dec 4, 2007
Messages
14
Reaction score
0
Location
Indiana
A piece of closed foam insulation floated on the surface of the mash will keep temp very stable.
Thats a great idea! Probably work really well to pour the vorlauf onto not have to worry about disturbing the grain bed.
 
OP
Pelikan

Pelikan

Well-Known Member
Joined
Oct 19, 2008
Messages
901
Reaction score
13
Location
Q Continuum
I hope it's not that "Great Stuff" spray foam you can get in the hardware store. I can see some seriously nasty flavors/birth defects from that being used.
 

ChemE

Well-Known Member
Joined
Mar 3, 2008
Messages
596
Reaction score
20
Location
Columbia, SC
What kind of foam did you use? Any problems with the expanding foam bulging the lid?
Great Stuff Door and Window and no, I drilled a weep hole on each side of the lid and shot the center until all the weep holes were weeping. Let it cure and cut each weep hole off flush and seal with white silicone caulking. That made a big difference in how long it takes my MLT to drop a degree.
 

ChemE

Well-Known Member
Joined
Mar 3, 2008
Messages
596
Reaction score
20
Location
Columbia, SC
I hope it's not that "Great Stuff" spray foam you can get in the hardware store. I can see some seriously nasty flavors/birth defects from that being used.
Maybe you're not using the lid of your MLT correctly; because in a typical brew session the wort never contacts the inside of the lid of the MLT. :drunk:
 

flyangler18

Well-Known Member
Joined
Jun 5, 2008
Messages
5,559
Reaction score
43
Location
Hanover, PA
I hope it's not that "Great Stuff" spray foam you can get in the hardware store. I can see some seriously nasty flavors/birth defects from that being used.
Cured Great Stuff is perfectly safe - besides, you are injecting the foam into the hollow plastic lid of the cooler where contact is minimal.
 
OP
Pelikan

Pelikan

Well-Known Member
Joined
Oct 19, 2008
Messages
901
Reaction score
13
Location
Q Continuum
Cured Great Stuff is perfectly safe - besides, you are injecting the foam into the hollow plastic lid of the cooler where contact is minimal.
Point taken, although introducing something like that to the MLT would still give me slight pause.
 

Cpt_Kirks

Well-Known Member
Joined
Sep 11, 2008
Messages
3,705
Reaction score
57
Location
Lakeland TN
Be careful not to add too much. My Igloo MLT lid is a little misshapen now because that stuff expands so much.

But MAN, does it work. I did a 8 gallon batch of blonde ale in it yesterday and only lost a half a degree in an hour.

:mug:
 

Brew-boy

Well-Known Member
Joined
May 31, 2006
Messages
2,272
Reaction score
18
Location
Lapeer, Michigan
I have the Blue square Igloo and I filled my lid with the "Great Stuff" foam the best thing I ever did. I would loose around 5-7 degrees in a 60 minute mash. Now I only loose around 1-2 which is no big deal to me. Never have I gotten an off flavor from this, my lid was hollow. I drilled a few small holes and injected the lid untill it was full problem solved.
 

Anthony_Lopez

Well-Known Member
Joined
Mar 2, 2008
Messages
1,533
Reaction score
29
Location
Groton, MA
I have a few solutions for this type of issue. The first has been mentioned - Wrap the cooler with a blanket.

When I brew outside during the winter, I know that my MLT is going to cool a little bit more than normal, so if I want a mash temp of 155*F, I start my mash at 156 and typically end around 154. This keeps me in the temp. range I want for the longest portion of the mash.

Also, reflectix insulation wrapping the cooler is very effective.
 

ChemE

Well-Known Member
Joined
Mar 3, 2008
Messages
596
Reaction score
20
Location
Columbia, SC
...Also, reflectix insulation wrapping the cooler is very effective.
I've been curious about this for my MLT. Do you find it more or less effective than wrapping your MLT with a thick blanket? I eye this stuff every time I walk by it at Home Despot.

Thanks,
ChemE
 

Anthony_Lopez

Well-Known Member
Joined
Mar 2, 2008
Messages
1,533
Reaction score
29
Location
Groton, MA
I have made four "jackets" for my carboys with this stuff, as well as wrapping my Minibrew 15Gallon MLT with it. I love the stuff. Make sure you get some of the aluminum HVAC tape if you are going to use this stuff. The tape is sticky as hell, but if you have any residual oils on the vessel you are taping to, you'll need to clean it off with rubbing alchohol or a similiar solvent. If you do use the tape, watch out cuz the stuff will cut the hell out of your fingers...
 

ChemE

Well-Known Member
Joined
Mar 3, 2008
Messages
596
Reaction score
20
Location
Columbia, SC
Sweet, thanks for the tips. I might have to give this a whirl before my next brew session. Late this summer I'm going to attempt to convert my BK to electric and this stuff and some heavy duty insulation are going to be major players in that effort. For the heating source I'm going to strike out in a new direction and try these little gems...

McMaster-Carr

1,120 watts in a 12" disc + some rectangular sheets will easily heat and boil 7 gallons of wort.
 

android

Well-Known Member
Joined
Jan 31, 2009
Messages
3,060
Reaction score
50
Location
Ames, Iowa
Like This


You can also poke your thermometer right thru.
i couldn't quite tell from the picture, but do you use the plastic lined side for on top of the mash or did you peel that off and not care which side ended up on the mash?

thanks for this info. I lost 7 or 8 degrees on my first AG mash. i also stupidly opened the lid to stir an extra time which quickly lost me a few degrees.
 

McKBrew

Well-Known Member
Joined
Oct 19, 2006
Messages
8,190
Reaction score
39
Location
Hayden
One thing that made a bit of difference for me was using a bungee cord to pull the lid down tighter to the cooler, I was losing a bit of heat at the loose seal on top.
 

BeerPressure

Well-Known Member
Joined
May 19, 2008
Messages
836
Reaction score
7
Location
Dunkirk, NY
Also, preheat your MLT with 175-180° water and allow it to drop to your desired strike temp before dough in. Otherwise, the cooler will suck away major heat and you'll miss your strike temp and continue to lose heat over the hour-long rest.
Are you saying heat your strike water to 175-180 then wait for that to drop in temp?
 

flyangler18

Well-Known Member
Joined
Jun 5, 2008
Messages
5,559
Reaction score
43
Location
Hanover, PA
Are you saying heat your strike water to 175-180 then wait for that to drop in temp?
Yup. Heat the water to 175-180, dump into the MLT and wait for the temp to drop down to the strike temp necessary to hit your mash temp.

Works like a charm. :mug:
 

BeerPressure

Well-Known Member
Joined
May 19, 2008
Messages
836
Reaction score
7
Location
Dunkirk, NY
Yup. Heat the water to 175-180, dump into the MLT and wait for the temp to drop down to the strike temp necessary to hit your mash temp.

Works like a charm. :mug:
Alright, I will try that next since I too am having temp loss problems. My usual method was about 130-140 degree water from my kitchen tap to preheat the tun, drain then put in my strike water which was typically 165 degrees to hit a 154 mash which didnt always hold for an hour.
 
Top