Dedicated Herms Guide, Problems And Solution Thread

[Tim F]

most people seem to be using a keggle as the mash tun in these systems. What are the benefits of that over a rectangular esky (which i already have for my existing brew gear)?

 

[hsb]

Probably more an indication that HERMS rigs tend to have been upgraded already? S/S vessel bit more robust to rig up a mash return/good false bottom to ensure no stuck mash.
I've seen debates (on here) over rectangle v circle for mash tuns but from memory both systems can achieve similar results.


No reason at all you couldn't use an Esky Mash Tun that I can think of.
The whole rig including H/Ex could be in eskies, although have to be careful with elements in plastic eskies/buckets, plenty do it that way. Especially the States with their 'coolers'.

 

[asis]

most people seem to be using a keggle as the mash tun in these systems. What are the benefits of that over a rectangular esky (which i already have for my existing brew gear)?

My original tun was a round cooler so I already had a round false bottom. And the fact that stainless is pretty much forever and I liked the idea of only having stainless or silicone is my system.

 

[Frag_Dog]

I am in the process of building a HERMS.

Working on what to do for a tube coil. I have 50feet of 1/2 SS Tube that I'm looking to get coiled up. The pot I bought is a Big W 7.6L pot. I figure I can get about 5-6m in there. Looking at what others have done, this is a little short, 7m seems to be the minimum people go for. Should I ditch the pot and try and find a bigger one and go for more length? I have plenty of tube, just don't want to have to buy more of it if i come up short.

These are the measurements I'm working on...

Pot Size:
Inner Diam = 224mm
Inner Height = 200mm

Coil:
Tube Diam = 13mm

Max Inner Diam = 154mm
Max Outer Diam = 180mm

Height = 150mm (allowing 20mm at the bottom and 30mm at the top)

Coil Length = 6200mm

I've left a bit of room around the coil so it isn't cramped in too badly. I have 20mm either side and the 20mm / 30mm top and bottom.

Any advice suggestions? I'm going to get this rolled by a metal shop as my attempt to hand roll have failed pretty badly.

 

[cdbrown]

Have you considered doing a double coil?. I use a 7.6L pot with the double coil and it does a fine job - probably overkill based on how short a time the element gets switched on.

 

[Frag_Dog]

Have you considered doing a double coil?. I use a 7.6L pot with the double coil and it does a fine job - probably overkill based on how short a time the element gets switched on.

I sort of had, but I think coiling the SS is going too be difficult. I broke a bunnings pipe bender that i used previously with no issue on non-soft copper. This SS is pretty tough...

 

[scooter_59]

I sort of had, but I think coiling the SS is going too be difficult. I broke a bunnings pipe bender that i used previously with no issue on non-soft copper. This SS is pretty tough...

I have the same size pot and have shoved 6 mtrs of 1/2 " copper pipe into it and have no problems with temp control or ramp times . Although ss has different heat properties to copper .

Cheers
Leachim

 

[Frag_Dog]

I have the same size pot and have shoved 6 mtrs of 1/2 " copper pipe into it and have no problems with temp control or ramp times . Although ss has different heat properties to copper .

Cheers
Leachim

Thanks Lachim! What size batches do you run? Idealy I would like this setup to be able to do double batches (40L). The tube i have is pretty thin walled, and I can feel the temp change running water thru it.

Playing with the numbers, I may be able to get 7m worth in it.

 

[cdbrown]

Get it as close as you can to the bottom and as close as you can to the wall of the pot to increase the circumference of each loop. 6-7m is probably going to be sufficient, but it might just take a little longer to ramp up if doing step mashes or at mash out. It probably won't be that much as it's only a small amount of volume that goes through the HERMS at any time, so it does take a while to heat 40L of mash up.

 

[scooter_59]

Thanks Lachim! What size batches do you run? Idealy I would like this setup to be able to do double batches (40L). The tube i have is pretty thin walled, and I can feel the temp change running water thru it.

Playing with the numbers, I may be able to get 7m worth in it.

I have only done single batches with it . I have noticed that if I don't open the tap fully I can increase the temp very quickly as there is more liquid sitting in the coil for an extended period of time . If I open the tap full bore the temp takes a bit longer to ramp up . So what I do is fill my mash tun ( Esky ) with the desired amount of water for mashing in and set the temp and wait it doesn't take that long especially when you start mucking around with setting up the grain bill and organising the brew day . So as far as brewing a double batch it probably wouldn't add much time to your brew day .


Cheers
Leachim

 

[cdbrown]

By reducing the flow then of course the liquid has more time in the coil and is more affected by the HERMS temp. However the mash itself doesn't benefit at all - less flow of hotter liquid in or more flow of warm liquid in results in the same temp change in the mash. Leave it on full flow and allow the PID to heat up the HERMS water enough so that the outlet of the coil is at the desired temp. If the HERMS is boiling away and it's not reaching the temp then there's not enough coils in the water.

 

[gava]

Agreed, My first HERMS beer attempt overshot and then had troubles keep it steady because people said the slower the flow the better the exchange and quicker it works.. it worked to good..

Next brew i opened up the taps and let it work itself out and it worked a treat..

cheers for the info guys..

gav

By reducing the flow then of course the liquid has more time in the coil and is more affected by the HERMS temp. However the mash itself doesn't benefit at all - less flow of hotter liquid in or more flow of warm liquid in results in the same temp change in the mash. Leave it on full flow and allow the PID to heat up the HERMS water enough so that the outlet of the coil is at the desired temp. If the HERMS is boiling away and it's not reaching the temp then there's not enough coils in the water.

 

[cdbrown]

However - it pays to have a fairly runny mash as a stuck mash can cause problems. I've had a few where it's slowed down and when I cleared it the false bottom (by giving it a stir) the liquid coming out of the herms was way past target temp due to the residence time in the coil.

 

[yardy]

what ratio are we talking cd ? 3lt/kg ?

However - it pays to have a fairly runny mash as a stuck mash can cause problems. I've had a few where it's slowed down and when I cleared it the false bottom (by giving it a stir) the liquid coming out of the herms was way past target temp due to the residence time in the coil.

 

[raven19]

By reducing the flow then of course the liquid has more time in the coil and is more affected by the HERMS temp. However the mash itself doesn't benefit at all

Not really an issue though mate, as you are only concerned with the liquid temperature (where your sugars and enzymes are working).

 

[cdbrown]

Not really an issue though mate, as you are only concerned with the liquid temperature (where your sugars and enzymes are working).

Strange, I've had far better efficiency by ensuring the full flow rate and maintaining the mash temp rather than just the temp at the outlet of the HERMS. I would have thought that as the HERMS is only seeing a very small % of the overall mash volume that the mash would be the most important part and not what's coming out of the HERMS. I basically have my HERMS set 2C above what I want the mash to be and that keeps the tun at the target temp.

When I was making the HERMS the target mash temp my efficiencies were lower because the tun always lagged behind. Only a small amount of volume was getting the right conversion temps.

 

[asis]

Strange, I've had far better efficiency by ensuring the full flow rate and maintaining the mash temp rather than just the temp at the outlet of the HERMS. I would have thought that as the HERMS is only seeing a very small % of the overall mash volume that the mash would be the most important part and not what's coming out of the HERMS. I basically have my HERMS set 2C above what I want the mash to be and that keeps the tun at the target temp.

When I was making the HERMS the target mash temp my efficiencies were lower because the tun always lagged behind. Only a small amount of volume was getting the right conversion temps.

cd do you have your tun and return piping insulated?

I have always set my pid at my desired mash temp and get a very consistent 83% efficiency. (probe at the coil exit)

 

[mxd]

Strange, I've had far better efficiency by ensuring the full flow rate and maintaining the mash temp rather than just the temp at the outlet of the HERMS.

I don't think Mash Temp stability will affect efficiency, I believe I get better efficiency because of the constant recirculation. The temp delta my just give you more or less fermentable wort (attenuation ?)

N.B -> HERMS, temp control on wort return, full open valve, I don't stir during as I then get a slow (not stuck) sparge.

 

[cdbrown]

Any reason for measuring temp just before return to tun rather than outlet of the HERMS? There could be a bit of a temp drop across that silicone hose depending on the ambient temp. Maybe it is the constant recirc providing a good "wash" of grains.

 

[mxd]

I assume the recirc is what gave me my efficiency improvement from pre HERMS 40 ltr @67% to 60 ltr @80%.

I measure at the return as that's where I thought I read it should be, I also worked on the theory that if the return temp is at mash temp and the flow quick enough then the MLT will be at the mash temp at some stage.