Building a one pot RIMs system

[Simonh82]

I've been BIAB for a couple of years now and making good beer. Well over a year ago I won an Inkbird PID in a forum competition and have been meaning to use it for temperature control of my mash.

Well one 11 month old child, many sleepless nights and a complete lack of spare time later and I think I might be able to pick up the project again.

@Bigcol49 and @Grizzly299 provided me with some good advice and useful wiring diagrams in a thread last year but I had a few questions after tinkering with some parts tonight.

Firstly, I've got a PID, SSR and heatsink. Do I need to use thermal paste with the heat sink, like I would with a CPU heatsink?

Secondly, and this might be getting ahead of myself, given what stage of the build I'm at. If I have a voltage regulator between the SSR and the socket that the kettle will pug into to reduce the power during the mash rest, do I need to leave the voltage at a lower rate for the entire duration of the heating phase so that the PID knows what to do, or could I leave it at full power until it reached 60°C, then reduce the power as it gets close to mash temperature?

Thirdly, where do people measure temperature with the PID probe. I thought that I would measure at the output of the kettle as this would avoid over heating the mash but will the pump, hose and wort return system not cool it quite a bit? Is it a case of the parts taking a while to warm up and then the temperature stabilises?

Finally, how do people manage the return or wort to the top of the mash. My little brown DC pump seems to run at about 4-5L per minute on full flow and I can throttle it back to 1.2L/m using the ball valve on the output. So far I've only tested it with water but I hope that it can sustain the same or similar flow with grain and wort. How fast do people set their pumps during mash recirculation? Do you do anything to distribute the flow of wort into the kettle, or do you just stick the hose into the top of the mash?

Thanks!

 

[Bigcol49]

Hi @Simonh82

Do I need to use thermal paste with the heat sink

I used thermal paste when fastening my SSR onto the heat sink - it's awfully messy stuff and it gets everywhere!

do I need to leave the voltage at a lower rate for the entire duration of the heating phase so that the PID knows what to do, or could I leave it at full power until it reached 60°C

I think your question is about the PID "learning". If I remember correctly, I put the PID into Autotune with the power reduced by the voltage regulator. I didn't want the mash to scorch if the element was on full blast and I wanted the PID to "learn" the system as it would be used.

where do people measure temperature with the PID probe

I use an ACE tea-urn type mash tun. I placed my probe at the outlet tap, before the pump. I reasoned that any drop in temperature between the tap and the return to the top of the mash would be minimal (my hoses are insulated with pipe lagging). I also reasoned that placing the probe close to the heating element reduced the risk of the mash overheating or scorching.

How fast do people set their pumps during mash recirculation? Do you do anything to distribute the flow of wort into the kettle, or do you just stick the hose into the top of the mash?

I set my pump for a quite gentle flow rate - I don't want to disturb the grain bed.
I suspend one of these veg steamers inside the mash tun so that it just rests on the surface of the mash and direct the return flow into it. I got mine from Wilko - and I use Wilko's garden wire to hang it from the mash tun handles.

 

[aamcle]

A thing to check, is it a thermocouple or a PT100 a PT100 is very much the better option as it's more accurate and you can calibrate it.

If you set up a constant flow and then Auto Tune your PID it will take care of the heating for you, you should not need to mess about with other regulation. However most PIDs will alow you to reduce the power, using an internal PWM for the Boil if that matters to you.

Put the temperature sensor on the output of the heater as it will respond faster, you will also want to measure the temperature were the sort returns into the mash. If there is a difference between that and the temp you set you should adjust the set point so the correct temperature is measured at the wort return.

Aamcle

 

[Simonh82]

Thank you both. @Bigcol49 yes, I was thinking about the PID autotune function. I'd like to reduce the power a bit because when I ramp up temperature at the moment and vorluf the wort to try to keep the temperature even I find the wort I'm pulling from the bottom of the kettle is 15-20°C hotter than the top of the mash.

I think I've got one of those veg strainers somewhere. I'll give it a go on my next brew even if I don't have the controller ready.

@aamcle its a PT1000 probe. The Inkbird came with a K type sensor but I heard PT1000 was better. Good point about monitoring the temperature where it returns to the mash too.

 

[aamcle]

There is something badly wrong there, it sounds as if the returning wort is bypassing the grain bed.

A properly tuned PID will reduce the power as the measured parameter approaches the setpoint to prevent it overshooting. However if something were to change for instance the flow rate my PID can be set so as to make sure that the temperature can never overshoot by more than a predetermined amount.

I think your biggest problem is the huge temp variation through the mash, when I was BIABing I had a spray head to return the wort and the grain bed top to bottom was within 1 or 2°C.

I'm not sure I understand your systen, is it what the US call a kettle RIMS, something like a Burco with a heating element in the bottom of a traditional RIMS with a separate external heat source?

Can you post a diagram?


Atb. Aamcle

 

[Simonh82]

Sorry, I think I've confused thing. My RIMs system is only theoretical at the moment. Until now I have a 30L Burco which I BIAB in. When I raise the temperature of the mash, either for a step mash, or a mash out I use a combination of stirring and vorlauf to try to maintain a reasonably even temperature throughout the mash. I've noticed that the wort that is pulled off from the bottom of mash where it will have been in close contact with a 2.5KW element is much hotter than the rest of the mash. This is when the element is set on full wack and bearing in mind that the vorlauf isn't constant so some stationary wort trapped under the bag is likely to heat up considerably.

With the new system, I am planning on constantly recirculating with the pump to avoid hot spots near the element and also including a voltage regulator between the PID/SSR output and the socket for the kettle so that I can reduce the power of the element. That means the heating should be gentler and the wort near the element won't get significantly hotter than planned. I think it should also reduce the frequency if switching which will hopefully also be a good thing for the components.

 

[aamcle]

Right, I original used a Burco and recirculated into it, the bag sat on a stand 5-6cm above the element and wort was taken from the base of the urn and pumped back to the top.
It didn't work well in fact it was a disaster the flow rate had to be so slow to allow the wort to make its way through the grain bed that there was no real temperature control.

To make a recirculation BIAB work you need to have a basket for the bag to sit in something to hold it away from the urn sides, that's what I did and it's what the commercial recirculation BIAB systems do.

Contrary to what is often said the recirculation does little for efficiency as such but it offers good temperature control.

l

That's the posh basket I only got to use it a couple of times prior to that I had something cobbled together out of scrap.

Atb. Aamcle

 

[Bigcol49]

A properly tuned PID will reduce the power as the measured parameter approaches the setpoint to prevent it overshooting.

Hi!
Now that's interesting - I thought the PID simply switched the output current on or off. As it approaches the set point I can see mine switching the output current on for very short "bursts" and then off again.
How do you set yours to reduce the power?

 

[aamcle]

They do it them selves have an look a :-

https://upload.wikimedia.org/wikipedia/commons/a/a3/PID_varyingP.jpg

The Wiki article is long but worth the effort :-

https://en.m.wikipedia.org/wiki/PID_controller


Aamcle

 

[Bigcol49]

Hi @aamcle
My Inkbird PID has a 12V pulsed output - it isn't a variable output.
Feeding into a SSR means the output from the SSR is either 240V full on or off - there's no way to control the output. I incorporated a voltage regulator in the circuit to add some control, that is, to "dial down" the voltage going to the mash tun element in order to reduce the power output of the element.

 

[Simonh82]

Well I brewed on Friday night without the temperature controller but using the pump for the first time. On the positive side the pump helped to drain the wort through the counterflow chiller much quicker than gravity alone. It also delivered it to the fermentor at 18°C which is perfect. Under gravity the flow was so slow that I could only have a trickle of water coming through the chiller and it was much harder to get a steady temperature on the output.

On the down side I had a nightmare during the mash. Recirculation seemed to work fine but the mash seemed thinner than normal, which I couldn't explain. When I raised the grain bag at the end of the mash, I saw a significant hole had been melted in the bag, presumably the pump had sucked the bag down to the bottom of the kettle. The grain had then escaped and burned onto the element. Miraculously, when tasting the wort, I couldn't detect any nasty flavours, so I decided not to bin the whole thing. I tipped the remainder of the grain into the kettle and launtered off the wort. Then I did a couple of batch sparges to get up to my intended pre-boil volume. This actually worked remarkably well, given that I grind my gain very finely and there was 1KG of wheat in the mash. After the mash I had to scrape out the kettle and scrub the element free of any burnt residue. I then started the boil which took a long time to get up to temp as the wort was cooling whilst I cleaned the element. I carried on as per usual after that and still managed a respectable 75% efficiency. This is slightly lower than normal but I will have left more wort in the grain than I usually do.

I think if I'm going to make this work, I will need to get a false bottom of some kind. I might try a pizza tray with a few bolts for legs. Apart from melting on the element, the bag didn't seem to perform badly and even switching the kettle on and off manually, I was able to stop the wort overheating, which I'm sure would have been happening when I did manual step mashes.

 

[aamcle]

A bit of an upgrade seems to be needed.

As I mentioned previously then bag should be supported in a basket of some kind, one that will keep it off the bottom and off the sides.

If you don't use a basket you will have on going and erratic problems, some batches will work some won't mainly depending on the composition of the grain bill.


Atb. Aamcle

 

[Bigcol49]

As I mentioned previously then bag should be supported in a basket of some kind, one that will keep it off the bottom and off the sides.

Hi!
If you needed a basket to support the bag, why bother with a bag - just mash the grain in the basket.
If you are going to use a bag, I would have thought it only needs to be supported by a false bottom to prevent the bag from touching the element.
I use an ACE boiler as a mash tun but I don't use a bag. It means draining the tun into a bucket, emptying the spent grain, rinsing and transferring the wort back into the boiler. This is a faff, but I think I'm getting better efficiency than I would do if I used a bag.

The flow rate had to be so slow to allow the wort to make its way through the grain bed that there was no real temperature control.

I have not experienced this with my system.

 

[aamcle]

I tried without a basket, I even tried with a stirrer I'd made from a windscreen wiper motor (entrily worthless) but in the end to make it reliable I had to use a basket.

I'd didn't believe that a stuck mash was possible with Biab but in a recirculation system it is, granted I had about 50% Rye and I hadn't added any rice hulls.

As far as I know all commercial 1V top down draining systems have a way for wort to bypass the grain bed, a centre of overflow in a GF or a basket in Biab based systems. Some have the basket made from fine SS mesh so a bag is not needed but all have a bypass.


Aamcle

 

[Bigcol49]

Hi!
I always mash with conditioned grain and haven't experienced anything approaching a stuck mash - just lucky, I guess - but I don't use a bag, just a false bottom.

 

[Simonh82]

I would really prefer not to have to use a basket. For one thing I don't think there is enough space above my kettle as I'm brewing in a pretty compact shed.

This may be my naivety but I don't really understand why you can't achieve the same thing with a bag. The bag drains very freely and I always get an excellent flow from the tap when valaufing during a temperature increase. I'm not doubting your experience but I feel like if I had hiked the bag up and secured it so that it couldn't touch the base it would have worked well, however I don't want to risk a reoccurrence of the scorched bag so I've ordered a pizza tray to act as a false bottom. I've gone for one with lots of holes to aid free draining and there will be a 1/2cm gap around the outside of the tray too.

If that doesn't work I'll rethink my plans I can't see myself getting a basket so I may just have to use the pump for chilling

 

[aamcle]

If you can manage without a basket go for it :)


Aamcle

 

[Bigcol49]

Hi Simonh82
Your pizza tray idea will work well - it will help in supporting the bag. Remember to add a bolt in the centre to avoid it collapsing.
I use a much thinner mash for my recirculating mash set-up - about 3.5 litres per kg; I read that this is quite common in German breweries. I would also recommend conditioning the grain before milling - you can aim for a finer crush without using rice hulls etc.

 

[Simonh82]

Hi Simonh82
Your pizza tray idea will work well - it will help in supporting the bag. Remember to add a bolt in the centre to avoid it collapsing.
I use a much thinner mash for my recirculating mash set-up - about 3.5 litres per kg; I read that this is quite common in German breweries. I would also recommend conditioning the grain before milling - you can aim for a finer crush without using rice hulls etc.

Thanks @Bigcol49, I was going to put 3-4 bolts as legs around the outside. Do you think I'll need the middle bolt if I'm leaving the bazooka filter in place underneath?

 

[JonBrew]

I can also vouch for the pizza tray as that's what I'm currently using in my simple biab set-up to stop the bag touching the element in my brew kettle. I don't have a central bolt fitted and have never had an issue and I've brewed some big beers with 10kg+ worth of grain in the bag.

As it happens, I'm also in the process of upgrading to a brewpi single vessel RIMS system. I say 'I', it's actually my dad that's doing all the hard work. He's an electronic hobbyist so is dealing with all that side of it whilst I supply the parts and design for how the system will work.

So I cant speak to the electronic side of things at all, however, in terms of the temp probe placement, we've opted to house it in an extra long thermowell which I intend to stick directly into the mash. not as neat and tidy as not mounted into the kettle but, given that we're only using one temp probe, this seemed the most logical placement and I've seen a few other folk online who have gone the same route. I plan on using a 15 litre plastic fermenting bucket was my mash basket. I intend to drill big'ish holes into the base of the bucket to let the wort flow and i'll then put a fine mesh screen over the holes on the inside of the bucket to act as a filter. I had looked into the wire buckets you can get online but they tend to be pretty cha-ching!

my main reason for wanted to go the bucket route was for effective vorlaufing. my feeling was that if you vorlauf with just the bag, the subsequent action of lifting the bag out of the kettle (creating that teardrop shape) might somehow take away from your efforts of vorlaufing. I have no evidence to support this btw, it was just a hunch I had.

best of luck and look forward to hearing how you system turns out.