HERMS unit not heating quick enough

[agillies]

Hi all,

How can I get my mash tun to heat quicker?

I have a 50ltr HLT with a herms coil in it, with 2 x 2000w elements.
my Mash tun is an un-insulated (soon to be insulated with a special foam from the misses' work) 70ltr stainless pot.

I did a brew the other day, and for some reason (me) I was under the mash temp by about 5-6 deg.

It took forever to get to temp by recirculating through the herms, then takes ages again to get to mash out temp.

What temps do people set the HLT to for recirculation? if i had it boiling i'm sure it would have gone up quicker, but would that kill proteins?

Will insulating it make a huge difference?

Is it just that there is so much wort to heat up?

Would an element in the mashtun for ''emergencies" be a bad idea?

Cheers

Adam

 

[coopsomulous]

How long is your HERMS coil?

Heat transfer through the coil can be improved by a longer coil or a larger temperature difference between the 'hot' and 'cold' sides of the coil

 

[agillies]

It would be over a metre. the wort seems hotter out of it, i'm in the process of adding a thermometer in a T piece just to check.

 

[Online Brewing Supplies]

Our HERM-IT HX has approx 1.7L of water to 2Kw of power.
You have 50L to 4Kw, here is your answer.
Lots of good info on AHB about this sort of stuff.
Nev

 

[agillies]

Our HERM-IT HX has approx 1.7L of water to 2Kw of power.
You have 50L to 4Kw, here is your answer.
Lots of good info on AHB about this sort of stuff.
Nev

I have an urn that i replace the HLT water with, which is set to 70odd, so the 2 elements are just to maintain temps and raise a few deg here and there.

The issue I had was the sparge / hx water in the HLT was at the right temp, but it took ages for the mashtun to raise 6degree's.

Just for a guide, what would you set your HERM-IT too if you mashed in at 60deg instead of 66ish?

 

[dent]

In a perfect world (spherical mash tun in a vacuum, no losses and perfect thermal efficiency) to heat your 100L (HLT plus mash) of water 5 degrees with 4000W, it will take 8.7 minutes.

So there is your minimum figure. You can reduce this by using a proper HX of a reasonable size instead of a dirty big HLT.

 

[agillies]

In a perfect world (spherical mash tun in a vacuum, no losses and perfect thermal efficiency) to heat your 100L (HLT plus mash) of water 5 degrees with 4000W, it will take 8.7 minutes.

So there is your minimum figure. You can reduce this by using a proper HX of a reasonable size instead of a dirty big HLT.

Thanks Dent,

sorry for more questions, trying to wrap my head around this.

How would the time reduce by changing the HX size? if a 50ltr tank is at 70deg and a 1.7ltr HERM-It at 70deg wouldn't it take just as long to heat the mashtun wort?

what is the temp people set their HX to raise the temp of the mashtun? do they set it just a few degress higher than what they want? or a lot higher?

Thanks everyone for your time in responding.

 

[dent]

I used 100L as the figure since you are trying to heat both the HLT and mash tun. If you use a smaller HX you are only heating 52L or so.

If you set up your controller nicely, you can heat your HLT separately when you aren't trying to ramp your mash temperatures.

In the HERMS world we don't try to control the HX temperature, we control the wort temperature exiting the HX.

 

[agillies]

I used 100L as the figure since you are trying to heat both the HLT and mash tun. If you use a smaller HX you are only heating 52L or so.

If you set up your controller nicely, you can heat your HLT separately when you aren't trying to ramp your mash temperatures.

In the HERMS world we don't try to control the HX temperature, we control the wort temperature exiting the HX.

ohhh ok, so if i just add a t piece with a thermowell where the wort returns to the mashtun, i can control it that way. When i start recirculating just move the probe to the other thermowell.

If your trying to raise the mashtun to 66deg, would you set the controller to 66 or higher? (that is if the temp probe is where the wort is going back to mashtun)

 

[dent]

Not sure what you are doing with the two thermowells. A single thermowell on the wort coming out of the HX is typical - this can be at the coil or in the tube or whatever going back to your mash, just like you suggest. We are recirculating all the time, even when not ramping.

The controller should be set to your desired temperature. If your system is designed well, it won't overshoot enough to matter.

At the end of the day, consistency is key. Wort mashed at 66 degrees on your system will not be exactly the same as 66 degrees on mine, for various reasons. But it doesn't matter - they will be consistent, and you can tune your mash temperatures along with the results you want for your beer in the glass.

 

[Online Brewing Supplies]

If you wanted 66 you would set your controller to 66 and let it step it up for you.
How you have it would need to be calculated every time you changed the temp or volume, you need to get either a dedicated HX or a PID controller.
You are doing it the hard way.
Nev

 

[Truman42]

Just for a guide, what would you set your HERM-IT too if you mashed in at 60deg instead of 66ish?

66C. I set my PID to the exact temp I want my wort to be when it exits the hex coil. No higher.

Dont worry about trying to measue the temp of your mash. Measure the wort as it exits your hex coil (with a T like you say your going to do)

When i start recirculating just move the probe to the other thermowell.

Not sure what you mean by this as you should be recirculating through your hex coil for the full mash time. Wort should be leaving the bottom of your MLT, going through the hex coil which will be raising the worts temp to 66C then back into the top of your MLT. Measure the wort as it leaves the hex, set you temp controller and go and have a beer whilst it does its thing for your 60-90 min mash.

then you can start doing a stepped mash

EDIT: Yeah as Dent and Nev just said.

 

[agillies]

Thanks for all your help guys!!

Got a few things i'm going to change, which should help out.

A PID controller and seperate HERMS sound like a good idea.

 

[Camo6]

I love my standalone Herm-it heat exchanger. I can do a step mash while my hlt slowly ramps up to mash out temps. It also means I can heat my strike water independantly in the MT and not have to refill the HLT.
I've used an stc1000 to control my mash temps while I've been organising PID control. It keeps overshoot to .3*c either side of set temp so if you've got a spare one it'll do for a start.

 

[themonkeysback]

Not sure what you mean by this as you should be recirculating through your hex coil for the full mash time. Wort should be leaving the bottom of your MLT, going through the hex coil which will be raising the worts temp to 66C then back into the top of your MLT. Measure the wort as it leaves the hex, set you temp controller and go and have a beer whilst it does its thing for your 60-90 min mash.

then you can start doing a stepped mash

I think he is simply talking about measuring the temp of his HLT (which contains his HERMS coil) rather than measuring the mash temp.

Agillies,

Getting a smaller HEX vessel is not absolutely necessary. If you did it would mean you should only have to heat a much smaller volume of water for your HERMS, but many systems do use the HLT as the HEX vessel as well.

As noted above, during the mash, you only need to measure the temperature at the point that your HERMS coil exits your HEX vessel (your HLT in this case). You don't need to worry about the temperature of the water in your HLT until it comes time to sparge. Generally, the temp of your HLT is unlikely to exceed the temp you would sparge at, and is very unlikely to get towards boiling temps - if it does I suspect your HERMS coil is too short or you are recirculating your mash too quickly.

It is perfectly reasonable to stick with your current system:
Measure the output of the HERMS coil during the mash in order to control mash temps, then check your HLT temp before sparging.

Adam.