Adding Water During Mash to Maintain Temp

There should be no issues with adding hot water to maintain mash temperatures. The rule of thumb wrt mash thickness is 1-2 quarts/lb. Folks who brew via the Australian Brew in a Bag (BIAB) method exceed the 2 quarts/lb. value (with apparently no ill effects) so, yeah, go for it!

Please report back how this worked for you.

Cheers!

 

I suspect most of the conversion is completed in a fairly short time, so it seems like extra work for not much gain. This assumes you are using an insulated cooler for a mash tun (which won't lose much heat over the course of a mash). If you are doing stovetop mash, pre-heat your oven to minimum, then put your mash pot in there (that's how I do it with mini-mashes/extract batches.

However, if you wish to be super-precise, I doubt there will be much chance for harm that way.

 

A big +1 to placing your pot in your oven to maintain mash temperature, assuming that your pot will fit in the oven.

Cheers!

 

Have you measured the temp fluctuation that results from putting the pot in your oven?

 

I've wrapped my pot up in blankets with no ill effects for my mash. My oven only goes down to 175 and I only do partial mashes, so it's not ideal but I've held my mash temp pretty well for 60 minutes with no problems.

 

Try wrapping it with blankets and towels. This can be a lot more effective than you might think.

 

Adding hot water should be ideal for your situation.

Cheers!

 

Back in the day, yes. Today, no. There wasn't enough of a fluctuation to continue being concerned about it, just like there isn't when I use an insulated cooler. Air doesn't conduct heat into water very quickly. So while you might get a slight rise (depending what the actual temperature of your oven is on low verses your wort), it won't be much. The closer in temperature, the slower any changes will occur.

 

Step-mashing get the most from your grist.

Notes from a talk by Dr. Michael Lewis
Home Brew U March 27, 1993
http://hbd.org/ford/newsletters/ford0395.html

For American pale malt, optimum fermentability is obtained at temperatures of 55^ - 60^ C. (131^ - 140^ F.). At these temperatures, the beta amylase enzymes produce maltose most efficiently. This happens early in the mash in a fairly short time, approximately 20 minutes.

The alpha amylase enzymes, on the other hand, produce the dextrins that give us the total extract we desire at temperatures between 70^ - 75^ C. (158^ - 167^ F.). It is possible to mash American pale malt with a single temperature infusion. While this can be a reasonable compromise approach, it inevitably results in a loss of either fermentability or extract, since the temperature is not optimum for either.

The best plan for mashing American pale malt is a "temperature program" in order to obtain the optimum balance of extract and fermentability. A sample two temperature program, utilizing the popular "camp cooler" mashing method, would be something like this:

1. Stir in enough hot water at around 70^ C. (approximately 158^ - 160^ F.) to make a thick mash, so the temperature settles in between 55^ - 60^ C. (131^ F. - 140^ F.)
Initial mash temperatures as low as 50^ C. (122^ F.) are acceptable. Hold for 20 - 30 minutes at this temperature.

2. After 20 - 30 minutes, add enough hot water just off the boil to raise the temperature to 70^ - 75^ C. (158^ - 167^ F.) for the remainder of the mash period.

What many American home brewers don't realize is just how low a temperature American pale malt needs for optimum fermentability and how high a temperature it needs for optimum extract.

 

I almost always add hot water to the mash tun, either to maintain temperature or to do a step mash. I use an igloo cooler for a mash tun, and it will drop ~2 degrees in an hour if I let it. So I don't let it. A little boiling water added along the way does the trick. A couple things to bear in mind: 1) if you're going to do this, starting with a relatively dry mash (~1.15qt per lb) is a good idea; and 2) remember to subtract whatever you add to mash from your sparge water in order to achieve your planned pre-boil volume.

 

That's too much work. I wouldn't go any lower than 1.25 qt water/# of grain. You'll get doughballs and you'll have to stir for like the first 10 minutes, and then another 10 minutes because you're worried you didn't get them all. This sucks exponentially more when you're doing a big beer.

If you want to add half a gallon of hot water at the 30 minute mark you're more than welcome. As said above, just make sure you work this water into your preboil volume.

 

I cannot imagine anything bad that might result from a 3-4 degree drop. More important is average temp. As Gordon Strong emphasizes, you should only put energy into things that matter. As Charlie Papazian says, RDWHAHB.

 

If you are brewing at the 1-bbl level already, you are approaching the point where the thermal mass is sufficient that maybe just a bit of periodic re-circulation/stirring of the mash will reduce the overall temperature drop. I have seen the metallic duct insulation work well and seem to be temperature resistant to mash temperatures. Add it to the lid and at least the top 1/2 of the kettle and you will likely see a much more stable overall temperature.

 

Regarding the oven trick - if your oven only goes down to 175, consider heating it to 175 and then turning it off before (or right after) putting your mash tun in the oven. It is likely that the temperature loss from opening the oven door will bring your oven temp down somewhere in the ballpark of your mash temp. And if you have a well-insulated oven, it can probably hold that temp fairly well, particularly with a relatively large volume of liquid and metal that is already around 150F inside. Turning the oven on for short bursts as the temp goes down can also help keep it steady.

As with most things about homebrewing, you can control this scenario almost to perfection if you wish. Whether or not it is worth the effort to figure out by trial and error how to do it with a particular setup is up to the brewer.

 

This past weekend I performed the pot in the oven approach. My target mash temperature was 153°F. After adding the grains to the strike water (168°F) I was exactly at 153°F as measured by a lab thermometer (and also by a digital thermometer with a long wired probe).

I placed the pot (with grains) to my preheated oven (manually adjusted to 155°F). I placed the probe of the digital thermometer in the grains in monitor the mash temperature.

My oven’s lowest setting is 175°F so to maintain the mash temperature I would periodically (every 15 minutes via a set timer) would turn on the oven and turn it off when it read something like 154-155°F. Over the 75 minute mash the temperature was rock solid at 153°F as measured by the digital thermometer. Once mash was completed I placed the lab thermometer in the grains and measured the mash temperature after 1-2 minutes of contact time; the lab thermometer was at 153°F.

With a bit of effort (periodically turning on/off the oven) the oven mash method can achieve a rock solid mash temperature.

Cheers!

 

I would think that if you're talking about a mash that's occurring at the far ends of the usual spectrum (ie, ~146F at the low end, 157F at the high) this could result in noticeable differences. You might have lowered efficiency with the lower temp mash and a higher portion of fermentables with the higher one, especially if the temperature fell quickly. But I agree that for your garden variety 152-154F infusion, it's not going to make a noticeable difference if it slowly drops to 150 over the course of an hour.

 

What most folks have said in this thread is Dr. Michael Lewis is a moron.