Controlling the temp of my mash

So I just completed my 2nd all grain batch using the stovetop method mentioned on this forum. My mash process is a little tweaked from that one though because I only have one pot large enough to fit my grains. Here's what I currently do:

1. Heat my mash water in my brew kettle to +10-12 degrees my desired mash temp
2. Put my grains (in a grain bag) into the kettle
3. Attempt to maintain the temp for an hour by keeping the pot on low heat
4. During the last few minutes of the mash, I heat my sparge water in 2 smaller pots
5. When the mash is done, I put a colander on top of my fermentation bucket, put the grain bag in the colander to drain, and then pour my mash through the colander, rinsing the grains
6. Then I combine my heated water into my brew kettle and heat to desired sparge temp (while my grain bag is still draining)
7. After sparge, I drain the bag over the top of the kettle, and add my mash water.
8. Bring up to boil, begin brew.

Problem I've been having is maintaining my mash temp for that hour on the stovetop. If I let it go without any heat, the temp drops too much because there's headspace in the kettle and I'm also taking off the lid to stir occasionally. My last brew, my temp varied from the lower 140's to the lower 170's. Not good. I've tested out how much water temps drop in an hour in a cooler that I have and they drop about 10 degrees in an hour.

Do you think I should essentially do the same process, but instead of the stovetop, put it in the cooler and add hot water every 15 minutes when I open it up to stir? The cooler isn't modified at all but I figure it won't matter much if I have the grains in a bag right? Any other easy ideas for controlling the temp?

If you use a cooler, you shouldn't need to add hot water. I only lose a few degrees over the duration of the mash.

You could also look at insulating the pots you're currently using.

If you are measuring a 10 degree drop in your cooler in 1 hour I suspect most of that drop is happening in the first 5 minutes as the temps equalize. If that is the case put some hot water in the cooler for a while before you use it (and empty of course) for mashing.

If your cooler really loses 10 deg F after equalizing that would be something to look into. Should not be the case.

724b said:

If you use a cooler, you shouldn't need to add hot water. I only lose a few degrees over the duration of the mash.

You could also look at insulating the pots you're currently using.

Click to expand...

Yeah I think the cooler is going to be what I try next. I've also heard of people using the oven so I'll have to see if my kettle fits and the toy around with water for both methods. Just brewed 2 days ago so I won't be brewing again for about 2 weeks.

theonetrueruss said:

If you are measuring a 10 degree drop in your cooler in 1 hour I suspect most of that drop is happening in the first 5 minutes as the temps equalize. If that is the case put some hot water in the cooler for a while before you use it (and empty of course) for mashing.

If your cooler really loses 10 deg F after equalizing that would be something to look into. Should not be the case.

Click to expand...

There will also be a lot of headspace in the cooler too. How often should I be stirring it? I feel like that is where I would lose most of the heat.

theonetrueruss said:

If you are measuring a 10 degree drop in your cooler in 1 hour I suspect most of that drop is happening in the first 5 minutes as the temps equalize. If that is the case put some hot water in the cooler for a while before you use it (and empty of course) for mashing.

If your cooler really loses 10 deg F after equalizing that would be something to look into. Should not be the case.

Click to expand...

I would agree that preheating the cooler would probably take away a good portion of that temperature drop. Definitely do some tests, because using the cooler would certainly be easier than having to heat and constantly watch a pot on the stove.

Another option that I've heard of, is putting the pot with your mash in it, in the oven. You'd probably need to run some tests on this too, because I doubt you can consider the temperature knob on the stove to be very accurate.

Edit: well, I guess that's what I get for not reading the whole thread.

cyraxx said:

I would agree that preheating the cooler would probably take away a good portion of that temperature drop. Definitely do some tests, because using the cooler would certainly be easier than having to heat and constantly watch a pot on the stove.

Another option that I've heard of, is putting the pot with your mash in it, in the oven. You'd probably need to run some tests on this too, because I doubt you can consider the temperature knob on the stove to be very accurate.

Edit: well, I guess that's what I get for not reading the whole thread.

Click to expand...

Thanks for the input and the "preheating" the cooler tip. I'll be testing these two methods out for sure. How often should I be stirring? It's something I'll take into account during my tests.

If you are grinding or crushing your grain very fine and putting them into a paint strainer bag or similar, you may not have to worry so much about holding the temperature so constant for the hour. With a fine grind, most of your conversion will happen within the first 15 minutes so if you can hold your temp that long, you are fine.

Have you tasted your mash? Mine tastes like cereal when I first put it in and the liquid will be very hazy. Within a short time the liquid becomes clear and if you sample then, it tastes sweet. Yup, you have conversion. Leave it longer and let more of it convert but most is done quite soon.

If you do "brew in a bag" starting with full volume, get your temperature right and don't sparge you will get reasonable efficiency. If you start with lower volume and sparge, you may not see much change in efficiency. I calculated mine out to find that I had 78% either way.

on stirring: when I put my grain into my water in my ice chest I stir enough to be sure I have all the grain well broken up and assimilated into the water.. then I close it and don't touch it until 90 minutes pass. That's a bit longer than most.. While that is going on I heat my sparge water to 170F and put it in another ice chest.

Once the 90 mins is past, I drain out the first runnings (I don't bother with a mash out infusion). I then add half of my sparge water and stir for about 10 minutes.. let it settle for 5 then drain.. then repeat with the other half of my sparge water. All my draining is done with a hop bag attached to the end of a hose connected to my valve on my ice chest. I just let it drain as fast as it can. Some bits wind up making it to the hop bag but don't seem to make it into the wort.

My LHBS has a pretty good crush and with this method I consistently get efficiencies in the 85-90% range with up to 16lbs of grain in my 9G cooler. Could be other factors involved in my efficiency as well. I haven't tweaked enough variables yet to be certain what other things are contributing.. but I'm not really wanting to change much since I like the high efficiency.