Accurate mash tun temperature control

[Bill_g]

I have been all grain brewing for some years and have always used a square insulated mash tun which I bought from Brew UK. It works reasonably well, much improved by covering the mash with a sheet of aluminium foil and placing a 3 inch thick foil wrapped insulating layer of polystyrene above the foil. I also wrap the mash tun in an old duvet. Nevertheless the mash looses at least 2 deg C over 90 minutes, probably more particularly in cold weather. I am considdering whether to build a temperature controlled mash tun based on a 30 litre stainless steel kettle (part of my original brew set up, I now use a 50 litre kettle). The build would be no problem, I'm a retired electronics engineer so all straight forward as far as I'm concerned. I'd probably use a 230V silicon heater pad, a solid state relay and a commercial PID controller (could build one but not worth it).
The question I am trying to resolve is whether I will actually make better beer by keeping the mash temperature under tighter control? I have obviously 'Googled' this to death but can't find a really solid answer. The indications from some sources seem to be that most enzyme action is completed within the first 20 minutes, so accurate temperature hold over the whole mash time is not really too important.
Has anyone any experience of going over to tight control of mash temperature?
Why the interest? - I seem to be good at making strong 'dry' beers but struggle to achieve the desired sweetness with a little less alcoholic strength. So maintaining a continuous high mash temperature should give the result I'm looking for (hopefully!).

 

[LeeH]

Better, no. repeatable yes.

Looks at RIMS and HERMS on youtube if you want to go all in on temp control.

 

[strange-steve]

I agree with Lee, you probably won't notice any big improvement in quality. Several years ago I built a little PID controlled HERMS system for my picnic cooler mash tun when I was having temperature stability issues. I didn't notice any improvement in the subsequent beers and I stopped using it after a while because it was more hassle than it was worth.

 

[Drunkula]

I was listening to the Brew Strong podcast yesterday and Jamil was saying he gets a lot of questions about holding mash temperature and it's the least of your things to worry about. It's either in the episode "working with residual sugars" or "Mash Questions 05-08-17"

https://play.acast.com/s/thebnpresentsbrewstrong/b0e6f81c-e0db-11ea-9977-c7816dbd47eehttps://podbay.fm/p/the-brewing-network-presents-or-brew-strong/e/1494208800
He said it's nothing compared to a good yeast pitch rate and not pitching the yeast at too high a temp. A couple of times I've heard him and Palmer say that pitching a few degrees higher than the temperature you're going to ferment is bad and can lead to underattenuated/stuck beer.

 

[Buffers brewery]

I made a HERMS heat exchanger for my mash temperature control. Allows me to gradually increase the temperature through the mash, a kind of mash out I guess. Gets me a regular 80% efficiency on brew day.

 

[Bill_g]

Many thanks to you all for your replies and great advice.
The 'Brew Strong' podcast was particularly interesting and very relevant. I would conclude from this that I need to ensure that I operate at a high end mash temperature but simply holding mash temperature accurately isn't necessarily going to deliver what I thought it might.
I'd agree now with the view that holding mash temperature precisely would lead to greater constancy and repeatability, but I actually enjoy the spice of a bit of variation, as long as the beer is good to drink then I'm happy.
I also had a look at the RIMS & HERMS set ups on various Youtube videos. Very interesting but a step too far for me at present. However I can see that if I was running a microbrewery & supplying to customers then such set ups would be essential to keep a reliable product.
Having said that the tantalising prospect of an interesting build project might just get the better of me yet!

 

[foxy]

2 C isn't bad over ninety minutes. The mash temperature falls between 63-70 C. As you stated in your original post hold the higher end will result in a low attenuating beer which you are looking for.
Understanding Enzymes - Brew Your Own

Worth noting this paragraph, not including you but a couple of times I have read of brewers on this forum carrying out a slow dough in.

But like all enzymes, its activity reaches a peak, declines, and then drops precipitously as temperature increases. The rate is also dependent on the amount of enzyme present. It takes time for all of the enzyme to be destroyed, but what is still intact works very quickly. So as the mash temperature approaches 149 °F (65 °C), beta amylase is operating at its fastest rate but it is also being denatured.

This may seem trivial, but at these higher temperatures the denaturation is so rapid that the enzyme is mostly gone in less than 5 minutes. Also, in a homebrewer’s mash tun, where the grain may be poured into very hot water, the exposure to very high heat for the few seconds before the mixture becomes homogenous may work to destroy the fragile enzymes.