Creative Ideas For Maintaining Mash Temperature

I use a 10 gallon Rubbermaid cooler mash tun for mashing five gallon batches, and I've had it for a very long time. I'm not sure whether the insulation is wearing out, or there is some other factor, but it no longer seems to hold heat as efficiently as it used to. The temperature can drop as much as 7 or 8 F over 1-1/4 - 1-1/2 hours of mashing. I keep the mash tun tightly wrapped with blankets during the mash. I also pre-heat the mash tun.

I'm interested to know if others have creative ideas for maintaining a more steady temperature while using a 10 gallon cooler mash tun?

 

Thanks for the tips. I do preheat the cooler, use it indoors, and leave it off the floor.

What I haven't done previously is add boiling water (if I open the lid, I will lose a lot of heat), use loosely wrapped blankets (I use a pillow on top, then 3 layers of blankets tightly wrapped over that), or add a barrier over the top of the mash.

As for the insulation in the cooler, I added a lot of boiling hot water once and it significantly warped the inner wall, so that now there are "folds" inside. This may have affected the insulating properties somewhat. So it might be time for a new cooler, although the Rubbermaid has never been that good (I've always lost at least 4 or 5 degrees F since the beginning).

 

I just made a box out of 2x2 lumber, with a cut piece of paneling on one side. I made the inside dimensions (12" x 15") to just fit a heating pad. The cylindrical cooler fits nicely over this box (and also keeps it off the floor, although in my case, the box fits nicely on a small step ladder chair, high enough to allow easy draining later). The heating pad has three settings, and after experimenting with it, I will be using the highest setting. As suggested, I will also cover the top of the mash with a shiny lid, and loosely cover the entire cooler with blankets.

The little heat coming in from the bottom, and travelling along the sides of the cooler under the blankets may help maintain the temperature of the mash better. Also, adding the lid will also hopefully help maintain the temperature better.

 

Thanks, but my water to grain ratio is already reasonably high. I really think the problem is that the wall of the cooler is somewhat compromised. Also, using a 10-gallon cooler for a five gallon batch is not anywhere as efficient (in terms of overall heat loss) as doing a 10-gallon batch.

But the real issue is the significant drop in temperature compared to when the cooler was newer (used to drop only 4 or 5 degrees and now drops 7 or 8 degrees over 1-1/4 - 1-1/2 hours), and how to compensate for it somewhat.

 

Thanks, but no, I'm not out to impress anybody, and generally am interested in simple, practical solutions - otherwise I would already be using a Braumeister or RoboBrew. I'm still using the same Rubbermaid (actually Gott but almost identical) cooler that I started with over a decade ago. Like Charlie Papazian (who, I understand, continues to use his initial double bucket equipment to this day), I like to keep it simple for now (this could change in the near future as arthritis in my fingers is affecting my ability to lift heavy vessels). The steam approach does sound quite interesting, but is a little too technical for me.

I could invest in a new cooler, but with the rapidly developing arthritis, I'd rather use the existing one for now, and save the investment for a RoboBrew or Braumeister or similar device in the future when needed.

 

All my mashes have been indoors, except a few times when it was quite warm outdoors (I almost always mash indoors and boil outdoors).

I think you meant infusion, rather than decoction. I'm tempted to add some boiling water (maybe a liter or two) every 20 minutes or so. I could even add it without opening the lid, through a silicon tube attached to the outlet and raising the other end of the hose (attached to another vessel containing the boiled water) well above the level of the mash. It should spread reasonably well and evenly through the false bottom.

 

I understand that it's hard to equalize the temperature when adding it from above (heat rises), but I assumed that adding it from below, underneath the conical false bottom, where it can spread out, and then forced upwards by the pressure from below, would allow the heated water to penetrate upwards and more or less equalize the temperature. But perhaps you're right in that even this approach may not distribute the heat evenly.

When I remove the lid, a lot of heat does escape since there's a lot of air space above the mash (about half of the volume of the cooler), and the mash begins to cool. In 20 minutes, I would normally lose about 2 degrees, and perhaps even more when I open the lid and leave it open while stirring. I will have to experiment to see how much hot water I will need to regain 2-3 degrees each time. Adding a quart each 20 minutes means adding a full gallon of water to the mash. That does seem like a lot.

 

So, are you drawing the mash out fairly early during the mash? To do a decoction, bringing it up to a boil and boiling it for at least 15 minutes, could take 40 minutes or longer. With a one hour mash, that means you would have to draw it off no later than about 20 minutes of mashing.
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I use a pillow on top of the lid, then three blankets. With that I lose 7 or 8 degrees F.

Half of my response didn't make it for whatever reason. I think I added something like the following:

"On the other hand, I could drain a quart or so of the liquid portion of the mash, boil it, and add part of it back every 20 minutes or so".