False bottom, dead space volume question

[Jtvann]

I've forgot a brew hardware false bottom and a wilser bag that I've never used. I can set the height of the false bottom a few different ways, two really that make sense.

1- False bottom just above the temp probe. Advantage is I can never snag the temp probe pulling the bag. Disadvantage and main question of this thread is approx a 6 gallon dead space in a 20 gallon pot. I tend to mash in with 15ish gallons of water depending on recipe.

2- false bottom just above the heat element. Advantage is less dead space, again the point of this thread. Disadvantage is I could snag the temp probe.


Assuming that I AM recirculating slowly for at least 45 mins of a 60 min mash, does the dead space volume really matter? Not trying to weigh the pros and cons of recirculation. That dead horse is tired of the beatings. Assuming recirculation is non negotiable, does the dead space volume below the false bottom play in as a variable? Meaning is one better than the other or doesn't matter at all.

Thanks

 

[okiedog]

That sounds like a good topic for an exbeeriment. Most false bottoms are positioned below the temp probe. It is the temperature of the crushed grains in the mash (and the wort around them) that you want to monitor, but the temp of the wort below the false bottom should be similar. If you have HERMS or RIMS, temps should be very consistent throughout. Try it both ways, with the same brew and process, and record the difference, if any.

 

[RPh_Guy]

does the dead space volume really matter?

Nope! Things diffuse, especially with recirc!

Alternate solution: new thermometer to replace the one that gets in the way. Or just use an inline thermometer in your circulation loop.

 

[Jtvann]

Well, first batch in progress. Was shooting for 1.054 at 13.25 gallons and hit 1.054 at 13.5 gallons. Actually, I was draining the bag while heating to boil. I'm betting the extra .25 gallons came from expansion. It's right in the ball park either way for pre boil. Will have to see what post boil volumes look like after cooling.

Right at a little better than 70% which is comparable to what I had before. Maybe slightly better.


Recirculation went without a hitch. Flow was just right. Nailed the mash temp and pH. Brew Boss app gives a nice pretty straight line showing little to no variation.

 

[Jtvann]

Well, that's a big negative. False bottom is sitting too high for my immersion chiller to be completely submerged.

Good reason to try it setting lower with this same recipe and post results.

 

[MikeCo]

Can you pull the false bottom out of the kettle after mashing with a long hook of some kind?

 

[Jtvann]

Can you pull the false bottom out of the kettle after mashing with a long hook of some kind?

Probably could. Didnt have it on hand this time. Always next time.

 

[okiedog]

I'm sure that sometime in the past, I've seen a mash tun pictured somewhere, that had a shield (strap) welded over the temp probe. It was designed to protect the probe from being hit or snagged. I have no idea when or where I saw it.

 

[Jtvann]

I'm sure that sometime in the past, I've seen a mash tun pictured somewhere, that had a shield (strap) welded over the temp probe. It was designed to protect the probe from being hit or snagged. I have no idea when or where I saw it.

I'm using the brew boss setup which has a weldless probe. Dont know why I hadn't thought of it before, but I can back the probe out without losing seal. I can also just work a long spoon down and cover it during removal.

 

[Cato1507]

I'm using the brew boss setup which has a weldless probe. Dont know why I hadn't thought of it before, but I can back the probe out without losing seal. I can also just work a long spoon down and cover it during removal.

Before I got a probe with a rounded end, I would use a short piece of 1/4 inch heat resistant tubing to slide over my pointed temp probe. Fit perfectly and would keep the bag from snagging and temp readings were accurate.

 

[PsychoBiter]

There can be issues with recircualton if the amount of deadspace makes your "effective mash" above the false bottom too thick. We have dealt with it. Does it effect the beer, doubtful, but effects the making of the beer. We couldn't get good enough flow to recirculate.

We combat it now by adding an extra gallon of water to the mash and boil and extra hour or so, but we aren't in a race to finish brew day either.

We also added some rice hulls and cut down on our flaked on the toublesome recipe.

Maybe get a shorted probe if it snags the bag, but I would get the false bottom as low as possible.

We also added our temp probe in a T outside the kettle, but in the line of flow, the only issue is that you only get an accurate temp reading if you are running wort accross it with a pump. If the element is on we have to have pump running and decent flow through mash.