Herms Lag

[3G]

Hi All

My herms unit is into its maiden voyage atm. One question, my wort was exiting the HE at 66 degrees, the mash tun thermometer was only reading in the mid 50's . This continued for about 30 minutes. The temp probe is mounted in the exit of the HE and a PID turns the element on/off when it reads greater than the set temp. It is usual for the mash tun and the wort exiting the HE to be slow to react.
I turned the temp setting to 72 and the mash temp rose in under 10 minutes. Maybe i am getting alot of lag due to temp loss.

Sorry for the ramble.

 

[3G]

Here is a crappy phone pic
The far right is the temp of the wort exiting the HE for mash out.
The bottom right is the selected temp for the mash out and the upper midle is a reading from the probe in the middle of the mash tun.

 

[reVoxAHB]

Hi All

My herms unit is into its maiden voyage atm. One question, my wort was exiting the HE at 66 degrees, the mash tun thermometer was only reading in the mid 50's . This continued for about 30 minutes. The temp probe is mounted in the exit of the HE and a PID turns the element on/off when it reads greater than the set temp. It is usual for the mash tun and the wort exiting the HE to be slow to react.
I turned the temp setting to 72 and the mash temp rose in under 10 minutes. Maybe i am getting alot of lag due to temp loss.

Sorry for the ramble.

The first two sessions with my herms had a similar experience. 30 minutes sounds excessive, but my ramp times were slow and frustrating. My temp probe was mounted on the return (or inside) of tun like this:


Initial water testing seemed OK in terms of flow rate, even with the SS barb on inside of tun (where I attached silicone hose and a return arm under mash surface).. eventually realised my flow was severely restricted with the barb on internal, and hard plumbed it using a length of threaded pipe like this:



With that in place, flow is great and ramp times are approx. 1C every 1.5 in 50L tun.

I would look to calibrate your pid temp probe to that of your tun thermometer. I would also look at your flow rates and look for restrictions.

My overshoot is exactly 3.5C and while normal, I'm looking to minimise with use of insulation on hoses and more. I'm using a dedicated 10L exchanger/9M copper/2000W on/off controller.

reVox

 

[3G]

Here is the probe on the herms

The probes are both calibrated. The read the same and go up within half a second of any changes.
The problem maybe long hoses with no insulation and my return arm is a hose witha pair of multigrips on the rim of the tun so the wort is probably taking the path of least resistance and leaving the centre of the tun un warmed
. Still in the building stage.

 

[3G]

Sorry, long day and half pissed, better go check the sparge.

 

[Justin]

Few possibilities.

Heat loss through long hoses is one possibility. You want these as short as possible or well insulated. No point in pulling hot wort out of a hot mash tun, cooling it down in hoses, heating it up in the heat exchanger, cooling it down again and then back into the mash tun. You would have been better off just leaving the liquid in the tun to begin with. FWIW insulate your mash tun if it's not already, it will only help things anyway and will give you a more even temp throughout the whole mash. Doesn't look as nice of course though.

Flow rate is another one mentioned above. Pull your sparge arm out and see what the flow is like, measure the temp of the output here also so you can answer the first point above. If your flow rate is very low then you simply aren't moving enough liquid (and hence heat energy) to cause any change in the mash tun.

Another point. Where in the mash tun are you measuring your temp? If your probe is near the side then it might be influenced by temp loss through the wall of the tun (insulate the tun), or as you mentioned the flow may not be passing by the temp probe very reliably (channelling).

As you can see there are a myriad of problems in trying to pull off the HERMS idea. Makes a single step infusion in an esky look like a wonderful idea.

Hope you get it sorted, but I'd look at flow rate as a first idea.
Cheers, Justin

 

[jimmyjack]

Im sorry Im a little confused, are you measuring liquid exiting the HE or are you measuring liquid at mash tun return?

 

[Thirsty Boy]

Im sorry Im a little confused, are you measuring liquid exiting the HE or are you measuring liquid at mash tun return?

That's a point - I measure temps at the closest point I can to where the ex-herms wort actually hits the mash tun wort. About 3inches short of the liquid. That way you don't have to worry about heat loss in hoses etc.

You will still suffer a lag however - it should bear a relationship to how many minutes it takes you to pump the entire volume of your mash tun (lets just pretend its all liquid shall we) so if you have 20L of mash and you are pumping at 3-4L per minute - then thats a minimum of 5 or so minutes till the mash tun will start to balance out with the return temp. And the temps will not be even throughout your tun unless its stirred - so there might well never be a point at which your fixed mash tun probe matches your HERMS return temp.

A higher flow rate will pretty much always give you a closer match and better, more precise control with less lag and less overshoot etc. But you need to be careful that you can maintain it for the entire mash - your flow rate at the start might not equal your flow rate at the finish. I have been struggling with this since I first started using a HERMS/RIMS and as soon as I have time will be putting myself through a (hopefully) final re-design of my mash-tun false bottom set-up to give me the flow rates I want for proper control.

Get you system set-up and working so that you are happy that you have a handle on how the relationship between the mash tun and the HERMS output runs, then stop looking at the mash tun probe and just use the HERMS reading. Your mash can then be designed around that if you keep your other parameters fairly consistent.

TB

 

[Frank]

I would also change the temp probe and outlet hose around. Have the probe poking back toward your kettle, directly in the T. It would seem there could be a lot of 'dead' wort around the probe that would take a long time to measure heat differences.

 

[raven19]

Just to throw my 2c into the ring... was at 3G's last night checking out the HERMS system in action too.

The comments above should help in reducing lag times, etc.

I measure temps at the closest point I can to where the ex-herms wort actually hits the mash tun wort. About 3inches short of the liquid. That way you don't have to worry about heat loss in hoses etc.

I can confirm the end of the HERMS temp probe is within the T-Piece, but I think TB's comment re measurement of wort just before it hits the mash again will help immensely.

Looks like 3G has some more fabrication to do!

And if need be I can be there to supervise and drink more of his great beers on tap!

 

[3G]

... and ensure the herms is plugged in. Cheers Brad.

Thanks all for the advice.

 

[raven19]

... and ensure the herms is plugged in. Cheers Brad.

Thanks all for the advice.

h34r: I said nothing of the sort, true to my word! :lol:

 

[kirem]

I'll open the can of worms h34r:

enzyme denaturing?

 

[Goat]

Good point Kirem.

I elected to set the max temp within the HERMS HEX to 66deg to avoid de-naturing, rather than allowing the output from the HERMS to set the temp of the element. The reason being that if the temp of the returning liquor is less than the desired temp (through piping heat loss etc) , the element will turn on and possibly overheat the liquor (albeit temporarily) through the HEX resulting in denaturing.

I did a first run of my HERMS setup on the weekend and it was a total F***up ! After recirculating for about 2 hours the temp of the MT went up by about a degree. the runoff from my braided pickup had reduced to a trickle. False bottom here we come... 10Kg of Maris Otter turned into dog poo

 

[3G]

If i measure the wort exiting the HE, not the grain in the middle of the tun, and the pump is moving the wort thru the HE surely denaturing isnt an issue, regardless of the temp of the water in the HE.

 

[kirem]

so your temp point is the hottest part in the recirculation path?

 

[3G]

I'll open the can of worms h34r:

enzyme denaturing?

Yes, in the photo above the mash out temp is set to 78, the bottom right is the wort at the exit of the HE, also 78. The 68 is the reading from the very centre of the mash tun.

 

[Goat]

I would agree with that 3G.

However, controlling the HE water temp by the temp of the wort immediately prior to returning to the MT as per Thirsty Boy's setup, (I would have thought) could potentially cause a temp overrun in the HE water thereby raising the temp of the wort within the HEX - in a bad case this could raise the temp within the HEX to denaturing temps. Controlling the HE water by the temp within the Mash Tun would only make this scenario more extreme.

This is only my opinion of course - it should be noted that I am a HERMs user with a 100% failure record (1 from 1) with 1 day's experience !

 

[kirem]

IF I recall correctly, TD has argued in other threads that denaturing doesn't happen very quickly.

There is a graph on ahb somewhere (that I can't find right now) that shows the rate of denature versus temperature for beta and alpha-amylase. I think it was a post from Darren.

From memory the graph supports my thoughts that denaturing is something to be concerned with when deciding on a place to measure your temperature.

 

[NickB]

Personally, I find that with MY HERMS, I mash in, get almost the perfect temp, then 20-30 mins later, notice that my mash is 3-4c higher than I have set. Then, 20-30 mins later, I find my mash has settled to approx what I planned.

FYI - I have my temp sensor approx. 3" from the top of the mash, and from the last 10 or so batches, have been setting my TempMate to approx. 3c lower than my mash temp. This has given me very repeatable results.

However, I'm one of those luck buggers who have a bashed up old SS braid in my mash tun, and have never had a badly stuck mash...In fact, have just received a 9" false bottom from CraftBrewer, and can't decide if I want to fix what isn't broken, or make a glorified kettle manifold....................................

Cheers