Mash temp drops with Herms AG fly sparge

[butterman]

Hi All,

With my first Herms AG I fly sparged at 77C & a rate of approx .5L/min. The further the sparge progressed the further the mash temp dropped, finally to 72C. I had previously mashed out for 10mins @ 77C.

My reaction to this is that as the HLT reduces in volume there is not enough heated water/flow through the March pump to maintain the mash at 77C and the head pressure from the HLT, in my case, would be on the weak side since it is only about 2 feet above the pump (on my burner stand).

I tried reheating the HLT water to above 77C intermittenently with the burner during the sparge and even tried dumping a small amount of 77C+ water into the mash, but with negligible effect.

I understand that the loss of solubility of sugars below 74C could have a significant affect on efficiency and I would like to eliminate the problem.

I could increase the sparge rate but I'm not aware of the sweet point for optimum mash efficency ie., the trade off between temp and flow rate.

I would like to hear from you if you have some ideas on fixing the problem.

Cheers
butterman

[BDawg]

You can build a dedicated herms heat exchanger out of a round cooler and a hot water heating element in the center bottom. Then you don't have to drain it. Fill it once (hot, from the HLT), and use the electricity with a Ranko temp controller to keep it at temp and draw your sparge water out of your HLT as normal.

Take a look at this guy's HLT:
http://powersbrewery.home.comcast.net/~ ... y/hlt.html

Do it like that but keep it dedicated only to the HERMS, and use your regular old HLT for sparging.

HTH-

[raven19]

If you are fly sparging, you want a slow sparge not a fast one - so I would not be increasing your runoff speed.

Can you move your HERMS tubing to a separate vessel so it is independant of the HLT water?

Or keep topping up your HLT (which I assume contains your HERMS tubing?)?

Once you get the mashout temps to 77/78 - you could flick the pump off, fill the HLT up - let it get back up to 78 then start sparging (enzymes have been denatured by then so wort consistency won't change). Once too low, stop draining your runnings, then fill up the HLT again, wait till temp is reached then start sparging again.

A separate smaller HERMS vessel could be the go.

[dshepard]

Something is not adding up here. If your HLT is hotter than (or at least equal to) your mash, then your mash temp should be going up (or staying the same), not down. During this last session, what was the ambient air temperature? When it is cold I wrap my mash tun (S/S pot with false bottom) with a blanket, during the summer it is not needed. I use my HLT for my HERMS as well and as soon as I am satisfied that mashout is complete, I sparge from my HLT. I am using my return manifold to try and keep an inch or so of sparge water on top of the mash. Are you using a "whirly" sparge arm? If so you will get heat loss from that. If you are using a whirly type sparge arm, trying raising your HLT temperature a few degrees to compensate.

On my setup I gravity feed from the HLT to the mash and use a pump to pump from the Mash Tun to the boil kettle. I really don't know the exact rate, but I match the pump flow with the sparge flow to try and maintain the inch or so above the mash.

[Quin]

...I understand that the loss of solubility of sugars below 74C could have a significant affect on efficiency and I would like to eliminate the problem.

I don't think it's that big of a problem. I don't have any problem getting 80+% efficiency without doing a mashout. My mash is usually around 150F at the end of the sparge. BTW, I shoot for 1 qt/min for a 12 gallon batch (so about twice as fast) without any efficiency problems.

[butterman]

You can build a dedicated herms heat exchanger out of a round cooler and a hot water heating element in the center bottom. Then you don't have to drain it. Fill it once (hot, from the HLT), and use the electricity with a Ranko temp controller to keep it at temp and draw your sparge water out of your HLT as normal.

Take a look at this guy's HLT:
http://powersbrewery.home.comcast.net/~ ... y/hlt.html

Do it like that but keep it dedicated only to the HERMS, and use your regular old HLT for sparging.

HTH-

Hi,
Yes I omitted to mention that I have a dedicated HEX (modified Cornelius keg) with a 2200 watt heating element that is controlled by PID. My sparge water goes through the HEX via the March pump. With the mash process there is approx 3*C lag between the PID & mash tun. So I'm thinking that with the initial HLT water it probably might be an idea next brew for the initial sparge water to be 77*C + 3*C to have any chance of maintaining the sparge temp, at least for a while. The problem is going to be maintaining the temp over say 30-40 mins sparging. If I used the +3*C approach I would also have to set the PID to 80*C so that it didn't go to sleep..

Cheers

[butterman]

If you are fly sparging, you want a slow sparge not a fast one - so I would not be increasing your runoff speed.

Can you move your HERMS tubing to a separate vessel so it is independant of the HLT water?

Or keep topping up your HLT (which I assume contains your HERMS tubing?)?

Once you get the mashout temps to 77/78 - you could flick the pump off, fill the HLT up - let it get back up to 78 then start sparging (enzymes have been denatured by then so wort consistency won't change). Once too low, stop draining your runnings, then fill up the HLT again, wait till temp is reached then start sparging again.

A separate smaller HERMS vessel could be the go.

Hi Raven19,

Thanks for your input. Actually you have given me an idea to fix the problem.

What I propose to do is to keep the HERMS recirculation system separate from the influence of the HLT water (temperature) by introducing a brass Y fitting downstream from the MT output tap such that I can bleed off to the boil kettle with an inline barbed plastic tap. This will necessitate that I increase the height of my HLT for a gravity feed to an existing input in the centre of the lid of my MT cooler (instead of the existing input thro' the pump & Herms). I'm hoping this separation of Herms/HLT will do the job of maintaining the MT temp during the sparge cycle. I will test it out as soon as the Y fitting arrives and post my findings.

Do you see any reason why this will not work?

Cheers

[butterman]

Something is not adding up here. If your HLT is hotter than (or at least equal to) your mash, then your mash temp should be going up (or staying the same), not down. During this last session, what was the ambient air temperature? When it is cold I wrap my mash tun (S/S pot with false bottom) with a blanket, during the summer it is not needed. I use my HLT for my HERMS as well and as soon as I am satisfied that mashout is complete, I sparge from my HLT. I am using my return manifold to try and keep an inch or so of sparge water on top of the mash. Are you using a "whirly" sparge arm? If so you will get heat loss from that. If you are using a whirly type sparge arm, trying raising your HLT temperature a few degrees to compensate.

On my setup I gravity feed from the HLT to the mash and use a pump to pump from the Mash Tun to the boil kettle. I really don't know the exact rate, but I match the pump flow with the sparge flow to try and maintain the inch or so above the mash.

Hi,

Thanks for your inputs.

Ambient temp should have not been an issue. On the day it was around 25C. I am able to keep my oblong cooler closed for the duration of the mash & sparge, made possible by a height variable copper tube input (mash/sparge) in the cooler lid and provision for using a long stick thermometer through the lid. I only stir at dough-in, not at any other time. So heat loss in those regards should be at a minimum.


See my reply to Raven 19 about how I propose to try and overcome the problem.
Would be glad to hear your views on that proposal.
Cheers
butterman