The plumbing configuration of HERMAN has been tweaked over the years into something I'm very happy about. The thing is, that a change like converting from RIMS to HERMS can raise issues that I'd not thought about before.

Below is the current plumbing schematic of HERMAN as a HERMS. You can click on the image to see a larger version.

The HERMS coil in the hot liquor tun is a simple replacement of the inline heat chamber that was situated immediately after the pump. The problem with this arrangement, is that the normal backflush of the plate chiller, which is designed to be clean of biological matter, runs through the HERMS coil. The path is via the hot liquor in solenoid, down towards the HLT, then right and up in through the pump before a right via the backflush tap, then through the plate chiller and into the kettle (or draining from this point via a hose). The problem has become evident because the old HERMS coil has been slowly releasing biological matter under the pressure of the hot liquor in line.

Without realising it, the plate chiller was partially clogged with this unwanted biological matter. It must have been loosened up with the long vinegar wash a couple of days ago. As it is impossible to see what it inside, I was not aware there was more matter in there, waiting to let go at such an inopportune time.

I only noticed there was a problem when the first runnings from the kettle to the plate chiller released some of this matter. Despite all I tried, more matter continued to come out. Flushing did not help because the flushing just encouraged more matter to flow through into the chiller via the HERMS coil.

One workaround would be to move the 'hot liquor in' connection is to the backflush tap. This would mean then clean liquor can flow directly through the chiller as planned. Hot liquor still has a path into the mash tun and hot liquor tun, via pump and HERMS coil, but these areas are much less critical compared to post kettle. One problem I can see with this is that the other chiller cleaning process I commonly use is to fill the HLT with and oxidising cleanser (nappisan) and pump this through the chiller and then back into the HLT in a closed loop. This means that the HERMS coil should be placed above the backflush tap rather than below it. Doing this would eliminate it from this cleansing loop.

The modified layout is shown below. It might not be all that clear which cross overs are actually joints and which are passes behind, but the hot liquor in is connected just below the chiller, the the HERMS coil is only connected on the outlet of the pump. I will redraw and post a clearer schematic when I get time.

It looks like another extensive clean is in order, of both the coil and the chiller. And with a plumbing modification, I think we will be good to go.

I'm not sure whether to laugh at myself or kick myself. I guess I should laugh because I've never had any tuition in fluid dynamics (I'm not even sure that's what its called). My working with liquids, transfers, pumping, heating, chilling and the like is largely based on what seems intuitively right and seeing what others have done with their brew sculptures ...

Anyway I had trouble getting the recirculation path to flow while brewing yesterday. Actually I've had trouble for a while. I've had air get into the inlet side of the pump. March pumps don't like to suck air as they are not self-priming. The batch before yesterday, I forgot to underlet the false bottom - which potentially left air trapped under a heavier than usual grain bill. The other problem with that brew is that it had around 70% torrefied wheat in it. That is a challenge for any system, let alone a HERMS or RIMS. The other issue was that the connection between mash tun and false bottom was simply a piece of nylon hose that slipped over the copper pipe. Over time this was getting looser, and may have been a good place for air to sneak in.

Anyway I came up with what seemed to be a bright solution. If air is being trapped in the false bottom, why not provide a vent to get rid of that pesky air?

So while I added a hose clamp to keep the connection tight, I also removed a plug from the top centre of the false bottom and created a vent to the top of the mash via the shaft of the mixing paddle (see sketch below - click on it to get a larger version).

When I tried to recirculate (now confident there would be no air under the false bottom), flow was very slow. Obviously something was wrong. So I turned the pump off and began to drain some liquor from the mash tun into a collection vessel so that I could heat it on the stove as a pseudo decoction. As I was collecting, I noticed something quite strange. Liquor would flow then suddenly there was a gurgling that sounded like air and liquor mixing, with a dramatically different flow into the collector. Then things would restore to normal, only to have the cycle repeat. This was the point that I wanted to kick myself - the vent was now sucking air into the false bottom because the pressure under there was less than above while liquor was being removed.

I stopped short of self-harm when I realised that by taking the mixing paddle out of the mash, I would immediately close this vent to the outside world. And once this was done, I had a fabulous flow rate in the recirculation loop. The problem was that by now I was so behind in the little things that are part of a brew day, that I did not have the luxury to record things well.

So it looks like I should put the plug back in for starters. And always underlet the false bottom. And possibly ask more questions from those who actually understand these things.

Anyway, the Belgian Wit is fermenting nicely this morning. It is a bit early to tell if I will have trouble with the matter that escaped from the old HERMS coil with some ending up in the fermenters. I have some ideas about how to fix that problem, but that is for another blog entry. I also have some ideas about making the coil easier to use on a brew day, as it was a bit awkward trying to clean the HLT yesterday.

But after all that, some photos from the brew session yesterday, with my favourite the pile of citrus zest that went into the boil. As a note, last batch I steeped the citrus in a closed kettle for 10 minutes prior to chilling. The fragrance was very prominent during fermentation, but there is nothing left in the final brew. This one does not seem to be 'letting go' of the fragrant oils. The difference was a 5 minute boil before a 20 minute steep prior to chilling.

Above: 12 mandarines and 6 navel oranges zested and ready.

Above: The mash during the protein rest. You can see the mash inlet manifold above the grains.

The kettle during the early part of boil.

I decided that I'd had enough of mis-hitting dough-in temperatures due to the large thermal mass of the mash tun. The result seems to depend a lot on the ambient temperature, and I don't brew often enough to take into account a 40C day compared to 19C today, or 15C tomorrow.

So I set ProMash's thermal mass to 0 because I intended to pre-heat the tun. I was after a protein rest of 54C, and ProMash suggested 59C for dough-in.

I might have been more patient (maybe this is the problem ), but I doughed-in with the mash tun and liquor at 61C. It was pleasing to see that the result was a protein rest at 56C. A little high, but I'm not so worried today as I'm anxious about the step to 64C.

The mixing paddle was left to stir the mash with no liquor recirculating as the hot liquor tun was heated to 80C. I figured if this was too much heat, I could turn the pump off anyway. The liquor to grist ratio was around 2 litres per kg grain, which meant that there was sufficient room to top up the mash tun with hot liquor to help the step as well.

Some top up liquor was added to the mash tun and then I attempted to recirculate. I'll save the details for another post, but I struggled to get any meaningful flow in the recirculating loop. Damn - over to plan B, a pseudo decoction.

Eventually I managed to get things flowing again, but it meant that much of the performance testing of the machine was out the window. I decided on a long rest at 64C to recover from the stress of the day so far, and to give me a chance to get down to the local fresh fruit market to pick up some yummy citrus for the Belgian Wit.

The saccharification rest had lingered a little low at the early part of the crisis, so I set the HLT to 68 degrees after a while to allow the mash to slowly ramp up to 65C. After settling down, it was rock solid at 65.1. It is pleasing to see it working so well, although it is obviously very dependant on recirculation flow.

With about 15 mins to go, I let the mash sit without recirculating and heated the HLT to 85C - again testing the theory that doing this will speed up the step change, and that the HLT might settle at around 78-80 by the time the mash has reached mashout (around 75-76C).

I didn't actually time it, but it seemed to take a long time to ramp up from 64C to 75. It would have been great in hindsight to have the laptop acting as a data recorder so I could simply graph what was happening. There were too many hiccups and distractions today, so it would be good to have a simpler brew day and do just that.

One of the complications was caused by old malt coming out of the heat exchanger coil. I managed to fill the plate chiller up with the stuff and had a rotten time trying to clean it. I just hope that the brew is clean enough to not suffer contamination from here.

It seems the heat exchanger will be slower for step mashing, but there are some workarounds that look good - like pre-heating the HLT while the mash sits. With a good recirc flow, it looks like the heat exchange coil could be made more efficient - either that or slow the liquor flow down - I'll need to think about that.

Anyway, the Wit is now pitched and fermenting - this means that with the batch we did 11 days ago we should have about 80 litres to get us through the Autumn. I think a Kolsch might be on the cards next.

I put HERMAN through his paces yesterday just to double check things, calibrate temperature probes, sort out any leaks and to give him a cleaning run.

After sorting out a few drips here and there, I used my new digital temperature probe to check calibrations on the machine. First, the calibrating thermometer was checked. I tested it on some boiling water and ice slurry to give two known points. It read 100.5 degrees C and 0.4 degrees C respectively. This meant that assuming it was linear in response, I would need to subtract around half a degree from its reading to get a calibrated reading.

I had done careful calibrations on the mash tun probe a few years back, and it was still within 0.1 degrees of calibration. I was happy with this result - I don't think I can realistically do better than that. The hot liquor tun and recirculating liquor probes both needed some adjusting. Adjustments are done within the picaxe in code - more or less a set and forget method.

As an interesting side observation, the calibration for mash liquor in (recirculating liquor) that I did yesterday afternoon was 1.7 degrees out this morning. The main difference between these two moments was the ambient temperature. Yesterday was a pleasant 21 C outside and in the afternoon the laundry gets the sun. Added to this, HERMAN had been producing heat for much of the testing phase. This morning was much cooler. I suspected this might be the case - and will try and insulate the pipe where the probe sits. I intend to insulate much of the plumbing, and maybe this is the time to finish that job.

The new HERMS coil was then tested with a white vinegar and water mix. There are a number of things I was interested in finding out.

• what is the temperature differential between a stable HLT and a stable mash liquor?
• how long does it take to become stable?
• is there a way to speed up transitions without overshooting?
• is the heating in the HLT sufficient?
• how does the HERMS coil affect liquor flow?

The temperature differential between HLT and mash seems to be about 3 degrees C. This is what I remember from previous experiments, and I guess will be improved by adding insulation on plumbing. The greatest advantage of insulation, however, might be more efficient temperature stepping.

The system is slow to change in temperature. I had forgotten how slow HERMS is compared to RIMS. It took about an hour to rise from 34C overnight to settle at 50C in the mash tun. I'd anticipate that with grains this would take longer. Today I will be brewing with the machine. I intend to experiment with pre-heating the HLT (without recirculating the mash liquor) and then "sucking" the extra heat out of the HLT for a quicker step in the mash.

The HLT is not heating all the time while the mash liquor is heating up. This means that the heating capacity is not being limited by HLT - rather efficiency of HERMS coil and liquor flow.

The HERMS coil has a significant impact on liquor flow. The tap can be fully open, but the resistance of the flow path means that liquor flow does not seem overly fast. This is not a problem, as if anything it is still a little more than my normal recirculation rate. Too fast a flow will compact the grain bed. It might actually be an advantage to have the coil naturally restricting flow to prevent compaction.

At this point it concerns me a little how slow "step" changes will likely be. I will keep thinking about HLT pre-heating as an option, and also if it is useful to have a heat chamber as a booster element. My inclination would be to increase the efficiency of the HERMS coil and put all the heating in the HLT. I will just have to make beer to test the theory!

I've had a very satisfying day tidying up loose ends. I've added things like a clip to hold the 'fermenter in' hose - rather than let it dangle. I guess I've finally done all those 'roundtuit' kind of things that have been nagging. Usually the machine only comes out of its hangar when we want to brew. Those days are busy enough without having to worry about maintenance or improvements.

The hot liquor tun pickup tube never reached anywhere near the bottom of the tun. We would commonly tip the tun up to allow the last few litres of sparge into the mash tun. A simple fix - the pickup should deal with all but a few millilitres now.

For a while I've thought that the M15 compression fittings that are standard fare in Australia would be even more useful if they could be finger tightened and released. Here is my first attempt at creating a wingnut from a standard fitting. The 15C nut is drilled and tapped and the bolts at 180 degrees are fixed with locktite. I am planning to add some project box 'feet' to make it less stressful on fingers. So far this is looking promising - I'll have to wait for a leak test tomorrow to see if it really works.

Below you can see one of these in place on the mash tun manifold (in) line. One of those little bits I got around to today was labelling taps, as you can see in the photo.

I also did the work to convert HERMAN from a RIMS into a HERMS. The old copper heat exchange coil was badly oxidised and had the odd green patch on it. It was cleaned up with elbow grease and a white vinegar mix.

The coil below is ready to insert into the hot liquor tun. It still needs a vinegar wash through the inside of it. That will have to wait until tomorrow. The beer in the photo is the last pour of my American wheat. It had a touch of rye grain in it and was delicious. Even sadder than finishing this keg was the reality that I now have no beer ready to drink . I can't remember the last time that happened. At least we found a fabulous local micro that does take-aways called 2 Brothers. The plan is to brew on Friday - and with a Belgian Wit nearly fermented out we will somehow manage.

Yesterday I was working on the wiring on the back panel. Duct tape makes sure that it is all held in place. Now all I need to do is build a new cover DOH

And HERMAN is now looking very neat. All the wiring is hidden. All the disconnects are functional without spanners. All the hoses now have a home. Even the pens and clipboard have places to hang. All I need to do now is install some basic shelving to hold things like water chemicals, nutrients, scales and the refractometer.

And with the upgrade on the control panel, HERMAN 6 will be complete.

When HERMAN was first conceived I was a poor student living in a shoebox (small flat) with no workshop. The original machine was cobbled together bits of plastic buckets and copper pipe with compression fittings. It was much easier in 2001 for me to build electronic circuits and program computers than build fancy brew sculptures.

The real strength of that original machine was its control system. It certainly wasn't his good looks!

When I finally got a real job with a real house with a real workshop, it was time to improve HERMAN. The biggest problem was that the job was now so demanding that I didn't really have time to make massive changes. I did find an old computer desk on wheels that eventually became the structure that held all of HERMAN.

Because it was not well designed, it suffered from all sorts of problems - the most significant was that a boil-over would leak hot wort directly into a draw that held all the control circuitry. This happened more than once and I am still amazed that it only ever led to temporary loss of control functions, rather than a complete machine melt down.

In the photo below, the control draw is the white box sitting under the mash tun.

One of the urgent tasks then was to upgrade the control system. The open drawer was replaced by a sealed box. A kettle was also incorporated onto the structure. Before this we had been using a gas fired kettle outside, which was a real pain in the winter.

While it was great to have the new kettle and counter-flow chiller integrated into the brew sculpture, the little computer desk was now overloaded with things. But we had plans to build a well planned sculpture that we would be proud of ...

And then one day while walking the dogs along our usual path that took us between a golf course and the back of factory warehouses, a couple of stainless steel shelving racks appeared. The factory in question was a commercial kitchen fitout company - these racks had been pulled out of an old job. With some quick negotiating, they became the owners of a carton of beer, and we became the owners of a brewing sculpture frame.

We figured that the machine we are currently using is version 5.5. It is still in transition to version 6 because while the physical structure is pretty much finished, the control system has not yet been upgraded.

I wheeled HERMAN out of his cupboard today intent on cleaning up a lot of loose ends. The typical pattern has been to patch him together as quickly as possible so that he can make beer again ...

It has resulted in some pretty ugly workarounds that it was time to fix.

One of the 'nearly made it' design features of the version 5.5 hardware was the back panel which contained cavities for running cables - and therefore space to hide them. The oversight was that the back cover of this panel was glued to the rest of it. First job was to rip this nicely painted panel off to expose the cabling duct space behind it.

When all the cabling is done I will make a replacement cover that screws on this time.

Below you can see the cavity space with some existing wiring for the 12 volt downlights.

The cabling from the control panel to various tuns was randomly draped across the front of the machine because access to this cavity was next to impossible. Next some holes were drilled to allow cables from the cavity to match up with the mash tun and kettle.

Above you can see the connection to the mash tun temperature probe. This is the other side of the back wall cavity.

Underneath the mash tun and kettle shelf there was a lot of wiring of 240VAC through the solid state relay box (the grey box on the right). These blue cables just draped down in a messy way and it was time to clean them up. I decided that some wooden pieces running from front to back would do for a holding space.

While it still looks a bit messy from this angle, the wires no longer hang down and are not visible unless you really stoop down to investigate. When all is done, a false bottom will cover the wiring much like the back panel cover.

Some time was taken to fix a few things with the mash tun. The mixing paddle shaft was renewed which meant soldering a key for the mixer motor. A new rubber mat was installed under the false bottom and a hose clamp added to make the pickup air tight.

I found the old copper coil used for the heat exchanger. I intend to clean this up and fit it into the hot liquor tun tomorrow. I should be able to brew on Friday and test out the theory then. I am hoping the hot liquor tun will not be underpowered with its 3600 watts of electric heating.

The poor finishing of cables has been annoying me for a long time. It was good therapy to make inroads on this today.

All this thinking about HERMAN history has made me think about how well HERMAN has been functioning. I actually think that the first version of HERMAN was in many ways better than the current one.

The first one had plastic buckets and leaked way too often - so I'm not talking about the materials it was built from. Rather the simple heat exchange coil in the hot liquor tun with a recirculating pump worked really well.

Since 2001 I've changed quite a few things - all in the name of progress. While some things have really been good improvements, I'm using this reflective frame of mind to question some others.

The coding of the first machine was okay, but was really inflexible. One of the great improvements to coding was incorporating a HERMS batch language where a full brew session could be controlled by an easily changeable batch sequence.

Moving from an analog interface to a fully digital interface was a great advance. Those early temperature sensors were not well matched to a 5 volt system and there was lots of induced noise that I could not trace with the equipment I had on hand. Using Dallas DS18B20 temperature sensors has meant much better reliability and accuracy.

Having a control circuit that allows for a fully functioning machine without a PC attached is one of the greatest improvements - considering how often Windoze seems to crash. The irony is that with a dedicated picaxe control circuit, I have not yet fully implemented the PC interface to allow the best of both worlds. This means that the PC control programming with all its decision-making power and process control is not currently able to drive HERMAN. In this sense, the original machine was more capable than the current 5.5 hybrid.

The first HERMAN machine was a little slow moving from one step temperature to the next. It is difficult to change mash temperatures quickly when you are relying on a coil within a large vessel of water (in the hot liquor tun). When HERMAN was upgraded to a 40 litre system, a separate smaller heat exchange bucket was added. This meant the system was still a HERMS, but the hot liquor tun was independent of the recirculation loop.

This seemed like a good idea and it did work quite well - but it worked against principles of simplicity. I am quite challenged when it comes to keeping things simple. At the time I did not even have any idea why this option might not be as good as keeping the heat exchange coil in the hot liquor tun.

The extra bucket meant that I had lost the advantages of the original HERMS concept. It is beautifully simple in concept. The hot liquor tun needs to be 2-4 degrees C above the mash temperature at mash out and this is typical of the heat difference needed to maintain recirculating temperatures ...

Given the power demands of changing temperatures on a 40 litre electric system (at least 15 amps at 240VAC), the most recent incarnation of HERMAN was converted to a RIMS system. This uses a heating element in line in the recirclating loop to maintain mash temperatures. At the time I thought this was making progress, as direct heating is more efficient than using the coil in the hot liquor tun. I'm coming to the conclusion that it is much more difficult to control liquor temperatures this way, and that it means there is an extra control system needed as well. Both of these things work against the simplicity cycle.

I can vaguely remember the beauty of the original system. Once the heat loss in the system is known (and it is relatively constant - although affected a little by external temperatures), it is quite easy to dial in a hot liquor tun temperature and then watch the mash hit its target and stay there. With a heat chamber in a RIMS configuration, PID control is needed to try and work out how much heat is required and for how long before an overshoot happens. Timing and calculations are everything - and that is after you have figured out how to tune the system.

So I think the next run of HERMAN will be in a test configuration as a HERMS - just to satisfy my curiosity. I remember fondly of the set and forget process with the HLT. Maybe it will find its way back into HERMAN 6.

Oh well, 6 steps forward, 5 steps back. Even if I reinvent the wheel, so to speak, I have enjoyed the process.

I've not had too many spare moments of late - but today is the first day of four weeks leave, so I expect to be able to do some serious HERMAN development in between a couple of weeks overseas visiting family.

With the few snippets of time I've been going back over old posts on the Australian Craftbrewer website. I've never been good at documenting things (which is why I'm finding blogging useful), so I didn't really know when HERMAN first made beer. Until now that is ...

HERMAN has just taken his first steps! 
Yes, that's right, the brewing robot is 
doing his stuff, keeping my mash at an 
even 66C while I type.

Sat, 21 Jul 2001 17:03:31 +1000

You can find the whole post here.

The picture below is an original shot of that first machine. As you can see it is pretty ugly - a mishmash of plastic buckets and nylon hoses. But it did work - and quite well too - and on a student's budget.

The insulated vessel on the left is the mash tun. The black thing on top of the wooden pieces is the mixer motor that is still in use today. The vessel on the right is the hot liquor tun. Below it to the right is the most expensive part of the system - the March pump.

To the left of the pump set back under the shelf is the original control circuitry. It used a parallel interface card connected to a laptop computer running Windows 3.1. It was coded in VB3. One LED is lit on the control box which I think means that the pump was running.

The piping that disappears down towards the left of picture is the runoff into the kettle which sat in the bath tub. This first HERMAN machine sat on the washing machine.

There is a screen shot below of the original control program. It shows the layout on screen much neater than the real thing actually was ...

My ProMash records show this beer to be a Strong Belgian Ale. I did not even make a note in ProMash that this was the birth of HERMAN! It was all-grain brew number 17, almost a year since the first one.