Dedicated Herms Guide, Problems And Solution Thread

[dent]

A bolt should seal perfectly if executed correctly.

Use an M6 stainless steel socket head cap screw rather than a hex head bolt, so you have a nice round base of the bolt to work with. Make sure there are no rough edges remaining on the 6mm hole you drill. Do not use any washers on the inside of the pot. Fasten the bolt very tightly with a nut on the outside, then use a second nut to attach your earth lug.

You will not need any silicon or O rings with this method; there will be a very watertight metal-to-metal seal with the bolt head on the inside.

 

[squirt in the turns]

A bolt should seal perfectly if executed correctly.

Use an M6 stainless steel socket head cap screw rather than a hex head bolt, so you have a nice round base of the bolt to work with. Make sure there are no rough edges remaining on the 6mm hole you drill. Do not use any washers on the inside of the pot. Fasten the bolt very tightly with a nut on the outside, then use a second nut to attach your earth lug.

You will not need any silicon or O rings with this method; there will be a very watertight metal-to-metal seal with the bolt head on the inside.

This is true, thank you dent.

When my Crown urn's sight gauge snapped off in the now somewhat infamous implosion incident, I put an M6 stainless bolt through the hole where the fitting used to go, and it's watertight without any gasket or sealant. I think when I was building my heat exchanger I was just itching to get my HERMS finished and grabbed whatever bolt was lying around.

vanoontour, do the above and only hit it with silicone as a last resort.

 

[Vanoontour]

Cheers guys. Used a bolt as suggested. Penny washer on the underside and worked a treat.

 

[Fat Bastard]

Heat exchanger insulation yea or nay?

Currently building a new one out of some stainless tube and am in two minds about it. It has a working volume of 2.5 liters, 2500 watts and runs a Herm-It coil. Should work better than the 8l 2000W Aldi urn but would like to lag it anyway as then I won't have to polish it!

Does insulation cause problems with overshoot etc?

Interested to hear your thoughts.

Cheers,

FB

 

[Camo6]

I covered mine with armacell and found I was getting a bit more overshoot. I'm only using an stc1000 at this stage and was getting over .5c overshoot compared to about .3c without insulation. My vessel holds 4.5l however. I also find it easier to keep clean and dry and it looks shinier without. I'll be interested to see the differences when I switch to PID control.

 

[sponge]

For all of those who are running bigger elements (4.8kW etc) in their systems and have switches on their panels, what sort of switches are you using for the ~20A load?

I got myself some little illuminated 15A ones but haven't found anything for >20A without going to the industrial switchgear.

I was hoping to find something fairly small but still suitable for higher currents if anyone has any experience?


EDIT: The 15A ones I have will be fine for me for the next while as I won't be upgrading from my 2.4kW elements for a while, but since I have rated the gear in my enclosure for 25A (overkill, I know, but would rather have too much then not enough just in case) I was hoping to be able to upgrade these switches so that if I ever do upgrade to a bigger system I won't have to do anything to the panel and just upgrade the elements being used.

 

[dent]

I'll be interested to see the differences when I switch to PID control.

Avoiding overshoot is one of the main reasons to use PID - so long as it is tuned halfway correctly.

what sort of switches are you using for the ~20A load?

20A isn't that much for AC. Even something cheap like this would be fine. Heating elements aren't very hard on switches as there isn't much in the way of inrush like there would be for a motor.

http://au.element14.com/cherry/cre22f2bbrle/switch-rocker-spst-20a-250v-red/dp/1228447

 

[QldKev]

For all of those who are running bigger elements (4.8kW etc) in their systems and have switches on their panels, what sort of switches are you using for the ~20A load?

I got myself some little illuminated 15A ones but haven't found anything for >20A without going to the industrial switchgear.

I was hoping to find something fairly small but still suitable for higher currents if anyone has any experience?

Why not get your electrician switch the main current with a relay/contactor, then the switch only sees a small load. You could even use a relay that switches the 240vac from a 12vdc coil. Here's one on ebay with nice screw terminals. That way the switch can't give you a boot should something go wrong.

 

[shmang]

Why not get your electrician switch the main current with a relay/contactor, then the switch only sees a small load. You could even use a relay that switches the 240vac from a 12vdc coil. Here's one on ebay with nice screw terminals. That way the switch can't give you a boot should something go wrong.

Switching with a contactor is best way to do it.
The switch may be rated to 20A, but I've burnt a few out through direct switching.

 

[sponge]

That's what I was worried about as well. I think I might just go down the relay route and keep it all ELV where possible, although I haven't got a tx for the ELV side, you can pick those up fairly cheaply. Probably helps having something like that there if I ever go down the actuated valve road as well.

 

[a1149913]

Hey guys, i'm kind of stuck in making a decision and was hoping you guys could push me into making it.

I'm trying to decide if i should put my HLT element in the side of the keg or attach it to the bottom having it point straight up the middle. The thought being that if its in the middle it wont contact the copper coil, however it means i'll need to lift the keg up slightly to fit the element box under the keg.

Any tips/hints/opinions?

Thanks, J

 

[Camo6]

Having it on the side will keep it at the one level so, depending on the length of the element, will remain under the water level for longer. Having it underneath will pose a hazard if the seal leaks.
I've mounted my hlt element on the side and as low as possible whereas my HEX element is mounted underneath as it was the easiest way to get a good seal and the water level doesn't change. Couple of ideas anyway.

 

[idzy]

Hi Guys,

I currently have a HERMS unit that has 8mt of Copper in it, not sure of the pot size but probably about 10ish litres. It has a kettle element in a metal box underneath. I am looking at building a new one.

Reasons for this are there is some oxidisation on the copper and although this blows out after a little bit, I would prefer to remove the copper out of the equation. I am also looking at boosting my ramp times. At the moment for a 50 litre batch worth of mash, I am getting quite slow ramp times, particularly when getting up towards the 70s. It means that I really need to reduce the flow to nearly stopped in order to hit mash temps.

I am thinking of:
1x BigW 19L
1x Stainless Steel 1/2" Annealed Coil - 15m
2x Kettle Element (2200w)

Just wanted to find out peoples thoughts. I am particularly interested in opinions on my choice of pot size. I see a lot of people using quite small pots, but I am thinking maybe part of the reason for my ramp issues is water thermal mass, but obviously this needs to be balanced with not too much thermal mass to prevent overshoots.

I am also planning to use this on a much bigger system, hence the reason for 2 elements. Interested to hear your thoughts.

I suppose my options are to build as above. Or to replace my current coil with stainless and add another element.

Cheers,
Idzy

 

[sponge]

I've got an electrician in our workshop doing the cut-outs and wiring of my new dual PID controller and enclosure to replace my current dual STC's.

I kept putting it off due to needing some new hole saws and whatnot to cut the enclosure but there's some sparkies that are a little short on work today and I just so happened to have the gear with me at my desk (as their manager gave me the thumbs up to bring it in one day incase work was a little slow for the sparkies).

I should have a nice PID controller ready to go this afternoon so will look at doing the plumbing mods tomorrow and hopefully tune the PID's with a water test on Sunday.

 

[TheWiggman]

If you can do this, that's your better option. More power to the coil = more heat energy that can be transferred. Up the heat energy and you'll up the rate of temp change. Also, keep your water volume as small as possible.
For 23l batches 2.7m of 12mm stainless has proven to be very effective, so if you're going larger I think it would be a safe bet to just increase your coil length proportionally. Also, the smaller the tube diameter the better, but make sure your pump has the power to deal with the resistance to flow.

 

[sponge]

I've got an electrician in our workshop doing the cut-outs and wiring of my new dual PID controller and enclosure to replace my current dual STC's.

I kept putting it off due to needing some new hole saws and whatnot to cut the enclosure but there's some sparkies that are a little short on work today and I just so happened to have the gear with me at my desk (as their manager gave me the thumbs up to bring it in one day incase work was a little slow for the sparkies).

I should have a nice PID controller ready to go this afternoon so will look at doing the plumbing mods tomorrow and hopefully tune the PID's with a water test on Sunday.

The sparky is finishing it up now and lordy, it's a whole lot neater than what I would've put together myself, ferrules included.

The flying spaghetti monster has become a couple of nice, neat lines of red and black liquorice.

I won't be putting labels on it for now as I've just asked to have the HLT PID/pump controls on one side and the HEX PID/pump on the other for easy reference, but may throw some on when I get some time.

Either way, I should have something to play with over the weekend and get this tuned whilst I keep working on my bar setup.

 

[idzy]

If you can do this, that's your better option. More power to the coil = more heat energy that can be transferred. Up the heat energy and you'll up the rate of temp change. Also, keep your water volume as small as possible.
For 23l batches 2.7m of 12mm stainless has proven to be very effective, so if you're going larger I think it would be a safe bet to just increase your coil length proportionally. Also, the smaller the tube diameter the better, but make sure your pump has the power to deal with the resistance to flow.

Thanks Wiggman. Inly question is - my understanding was that the larger the heat contact area the better the heat transfer. I.e. larger tubing?

 

[sponge]

Wouldn't smaller tubing have better heat contact as there is more coil surface area vs wort?

Similarly with increasing the length of the coil..

 

[QldKev]

I always thought you needed heaps of coils/length in the HERMS. After using Nev's (Gryphon) coil I have changed my mind. It's stainless, 12mm and only ~2.7m-3m long. It transfers as much heat as a kettle element can produce to the wort, so any extra length in this case is a waste. You simply cannot transfer any more heat than what is being produced. Some people have even reported being able to run 2 elements on this one coil, but I cannot comment on it as I have not done it (yet). IMHO you are better off using the smallest volume of water in the HERMS, the less water the less thermal mass so quicker it can respond. Therefore the shortest coil you can transfer the heat with is the best. I prefer to keep the 1/2" pipe as a minimum all the way through the system, any less and you will restrict the flow. To me a decent ramp that the mash bed does not lag behind needs a decent flow, hence anything under 1/2" is out. But I am brewing a 112L (wort) batch, so flow of a 23L could be a lot less in comparison.

 

[TheWiggman]

Wouldn't smaller tubing have better heat contact as there is more coil surface area vs wort?

Similarly with increasing the length of the coil..

This is correct. For a given length of pipe, assume 100mm long, imagine the two scenerios -

1. Very skinny like a pen ink tube
2. 10m in diamater

With heat applied to the outside, which of these two options would heat the entire volume of liquid in the pipe faster? The skinny one of course. This is the basic principle why having a smaller pipe will allow more rapid heat transfer. There is obviously a lot more to it than this, and as QldKev says you'll suffer from flow restictions if the pipe is too narrow/long. Fine for positive displacement pumps with enough power, no good for centrifugal pumps.

Your comment about the pipe length QldKev is partly right. Minimising water volume is the goal, but the longer the pipe with heat applied to it the more opportunity for the heat to transfer. The ratio of pipe volume : water volume is the critical factor I believe. Generally with a larger pot the ratio will drop due to diamater and affect your ramp times due to the fact the element needs to heat the additional water. The HERMS coil seems to be an ideal ratio in reality.
In an extreme case, if you put say 10kW of energy into a single HERMS in a little PVC pipe, you will probably find the temp in the water will greatly overshoot your HERMS output temp as there is not enough heat transfer able to occur over a 2.5m pipe length to equalise energy in = energy out. The only way to overcome this would be to add more length, and increase flow up to a point.