15l Stovetop Herms

[Tanga]

Don't know, sorry, just going on my readings. Hopefully someone who does HERMS and has a bit more AG cred,can let you know. Looks awesome though, and affordable, unlike the 'ghetto braumeister' though that looks cool too.

 

[Tim F]

Well I have decided on the pot in pot design for the mash tun/false bottom. There's a few advantages - the outer pot works like a grant so there's no suction on the grain bed (good as long as it flows freely enough I guess) and I can just lift the grain pot out before boil. I was going to say I don't know why everyone doesn't do the same, until I did a script to plot the holes in an offset layout and realised there was 5,497 holes to drill :icon_vomit:
I thought I'd stuffed up the script but I checked and double checked and it looks right. Luckily the old man has agreed to drill them with his cnc router on autopilot. If it wasn't for that though I guess you could just cut slots in the bottom with an angle grinder?

Here's my hole layout, using 2.5mm holes.


And here's my vb script if anyone ever needs to plot a grid of offset holes (or point out my mistakes) It does one quarter at a time.

Private Sub DrawXY()

'reset fields if you are storing values in them

Me.xyvalues.Value = ""

Me.xvalues.Value = ""

Me.yvalues.Value = ""

radius = 130 'where you want to drill holes out to

x = 0

y = 0

xoffset = 2.5 'increment x by this for each string of holes

yoffset = 4 'each hole in the string spaced this far apart

yodd = 2 'additional offset for the first hole in each alternate string

stringcounter = 0

Do While stringcounter * xoffset < radius 'repeat until the radius is reached

x = stringcounter * xoffset 'position of string

y = 0

firsthole = 1 'this is the first hole of the string, apply additional offset on alternate rows

	'generate ys for x

	Do While Sqr((x * x) + (y * y)) < radius 'set up new holes on y axis until radius of circle reached

		'increase y offset for alternate lines

		If stringcounter = 0 Then 'apply the additional offset to alternate rows

			ystart = 0

			ElseIf IIf(stringcounter Mod 2, "odd", "even") = "odd" Then

			ystart = yodd

			Else: ystart = 0

		End If

		'set y value appropriately

		If firsthole = 1 Then

			y = y + ystart

			firsthole = 0

			Else: y = y + yoffset

		End If

'Do whatever you want with x and y values here, I put them in a field in access

Me.xyvalues.Value = Me.xyvalues.Value & "(" & x & "," & y & ")" & vbNewLine

Me.xvalues.Value = Me.xvalues.Value & x & vbNewLine

Me.yvalues.Value = Me.yvalues.Value & y & vbNewLine

	Loop

'increment x

stringcounter = stringcounter + 1 'start the next string of holes

Loop

End Sub

 

[Tanga]

Good to see. things are moving along. Just realised you're in SA. I'd live to see it in action when it's done. Brilliant!

 

[Tim F]

I've got most of the bits together for the PID enclosure now. The PID controller rocked up from HK with one of the relays rattling around in the case. Luckily it worked fine after it was soldered back on. The seller offered me $3 USD back for the inconvenience.

if in the future , you need me do something for you , pls feel freely contact with me .
I will try my best to help you .
Thanks in advance
Have a nice day and happy forever.

So that was nice.

One thing to look out for if you're going the cheap PID route like I did, it turned out the one I got, a REX-C100, is just a relay itself. To switch an SSR directly, you need a control current output which some PID controllers have built in. Mine just switches internally. It actually says it is rated to switch the mains directly but I'm not game to run mains through something that came with bits falling off it so I stripped the guts out of an old AC adapter and will run 240V into my enclosure, into the AC adapter, then through the PID to switch my SSR on and off to control the mains. I'll need to put a suitable resistor between the AC adapter and the SSR.

Other stuff I got
-Biggest enclosure I could find - still be a squeeze I think
-Mains socket for the kettle to run off
-Cable grommets
-Terminal block to split the mains power inside the enclosure to go to the PID, the AC adapter and the SSR
-Sweet blue LED power switch
-Black extension cord to power the enclosure

And the SSR is also on its way from HK!

Total cost of all electrical parts was about $55.

 

[dent]

Not sure what your idea is with the resistor. The Rex PID will switch 3A 240VAC from memory, and since you are using it to control a SSR with next to no drive current I don't see why you wouldn't use it directly, rattly bits nonwithstanding.

I have a couple of the REX units, so far I am not impressed with the temperature accuracy of the K thermocouple models. Also they seem to vary with the temperature of the PID unit itself.

If your probe is like the one I recieved, be careful to insulate and/or earth the metal sheath of the probe wire inside your box - it would be a bit too easy for this to come into contact with the neighbouring 240V terminals.

 

[Tim F]

The SSR I bought has control voltage 3-32V and control current 3-25mA. So if using that I needed some way to deliver the lower control current.
I wondered about using the PID to switch the kettle directly but everyone is always going on about heatsinks and SSRs - wondered if its really safe to switch mains with the PID directly since I also plan to use this for sous vide cooking & it might be on for a day at a time.

Cheers for the tip re the probe.

 

[dent]

OK, if you have DC controlled SSR, but the resistor is not necessary. It is not like an LED or transistor where you have to limit the input current - the input impedance of the SSR is already rather high.

Not that it would cause any problems if you put one in - your plan will work fine.

 

[Tim F]

OK after actually reading the manual this controller can act as a relay but it also has control current on 2 other pins. So didn't end up needing the AC adapter. I got the controller all wired up with everything bar the SSR, which is still in the post. Here's my wiring, it was pretty simple so hopefully I got it right, but I will be running it past an electrician in the family before plugging it in. Once I get the SSR connected I will neaten everything up, cable ties etc, fix down the components, bling it up.


I didn't know if it was necessary to connect the ground to the AC out but figured it might not be a bad idea. But like I said I won't be trusting my wiring skills enough to turn it on without having it checked.



I put a power outlet with switch on the box so I can turn off the kettle but keep the controller on to read temp etc, if I ever want to.



Added a ball valve to my mash tun using a silicon baking tray to cut some washers. No leaks, always nice.



Connected the coil to the kettle properly, it was a pain in the ass doing up that bottom compression fitting inside the kettle. In the end I did it up before I dropped the coil in and stretched the kettle out of shape until I could wiggle it down to the hole.



Here's the whole thing so far. Obviously the pump will sit in line between the MT and HEX and the hoses will be shorter and the whole thing insulated as much as possible. I'm using hose barbs for now but I think I might upgrade to a camlock at least on the MT outlet once it all works how I want. They are cheaper than I thought. I'm also thinking about not drilling a hole for the return to the MT and just running the hose under the lid of the pot. This will make it a lot easier to move the hose to the fermenter and just pump out the MT/kettle after the boil.



Still to do:
Add a T piece to the HEX outlet with the thermocouple mounted
Add a small valve inline on the bottom of the HEX to throttle back the pump if nec - I understand it is better to restrict pump outlet than inlet?
hook up the SSR when it arrives
Buy a better pump - I have settled on one of these but I will use my peristaltic pump until that arrives.
Get the grain pot/false bottom drilled out
Insulate everything
Brew!

 

[Bizier]

Good work Tim, I was a little disappointed you did not get the tiny pump... I was hoping you would be the tester of that

I like your setup and hope to do something similar one day. Please post more reports.

 

[Tim F]

I know, I really wanted it but just don't think it will be quite big enough. I might get it anyway just because it's cool and use it for 5L batches :icon_cheers:

 

[dent]

Those brown/beige pumps are actually surprisingly awesome for the price/size, you might end up preferring it over the peristaltic.

 

[Tim F]

Yeah I think it will be better, the only advantage of the peristaltic is being able to come in over the top without priming, so no taps etc. But that beige one gives a much better flow rate. When I was researching pumps I actually found a whole bunch of similar even cheaper pumps on alibaba.com, different capacities but all food safe but you have to buy them in minimum lots of 200. Briefly considered a bulk buy but I'm sure a lot could go wrong with buying $2k worth of cheap pumps from China...

Does anyone see issues with this approach for mounting the thermocouple? I was thinking I'll crimp a section of thin aluminium pipe on one end, drop it through a brass bush in a T piece, and fix it into the bush with silicon. Then just drop the thermocouple into the open end of the tube with a bit of thermal compound from my PC supplies.

 

[Tim F]

Got the SSR today and hooked it up but unfortunately I was right the first time - the REX C-100 does not have a control current out, it is just a mechanical relay. Apparently there are some models of the C-100 that do have this but the cheap ebay ones generally don't. So I could go back to using my AC adapter to switch the SSR but I just found another interesting idea on a forum. Apparently the relay in the PID is switched by 5VDC and you can just do a simple mod to the PID so instead of switching the relay, it just feeds that to the out terminals directly. So I reckon that's the go - will take pics to show how it goes.

 

[Tim F]

OK so I have the control box working and used it to run a kettle tonight. Pretty tempted to hook the whole thing up now and see how quick it ramps, but no false bottom yet.

This was a pretty easy hack for anyone who gets a REX C-100 PID and wants it to run an SSR directly rather than just switch an external DC source to run the SSR. Now I have 13VDC on pin 4/5. Yes I got the wire colours the wrong way round.





I also made a ghetto heatsink for the SSR from some scrap ally and bolted that on with a bit of thermal goop in between them. I'll drill some air holes in the box, toying with adding a fan but I'll wait and see if it's needed first.

 

[Tim F]

She works! That's a good feeling. I just watched the PID cycle the kettle beautifully, after about 10 minutes it was holding 65C +/- 0

My peristaltic pump isn't going to cut the mustard though, it mustn't like all that friction upstream from the coil. I was only getting a trickle, so off to ebay for the beige pump.

 

[Tanga]

Congrats man. It's looking good. Hope the beige beast is gonna work. Must be frustrating to have to wait on eBay again. Go you good thing. Watching this with interest.

 

[Tim F]

Yeah I'm getting excited. Already thinking about what mash schedule to use for my first brew to maximise how much I can unnecessarily show off with it

I ended up ordering this pump from solarproject.co.uk rather than this one from ebay. The only reason I got the UK one (which was ~$15 more) even they they look and probably are identical is the uk seller replied to me to say the one he sells is food safe and the chinese seller said the one he sells is not. Figured there's always some chance the chinese one is a knockoff made from a different material but I probably just wasted the $15

 

[Tim F]

Just tinkering while I wait for the pump... I picked up a PT-100 temperature probe off ebay, didn't realise it would be so much more accurate. I also put in a screw down terminal block on the side of the case so I can change/remove the thermocouple/probe without having to undo the lid each time, then I attached all the components with nylon bolts. I also ordered a 40mm PC fan which I will mount when it arrives, as the SSR was feeling warm after about half an hour running the other night. I just spent the day at work perving at the Geordi catalogue too, I could change to all stainless camlocks for $90... h34r:

 

[scooter_59]

Only suggesting . If you are going to place the probe on the outlet side of your hex , all you need to do is buy an end cap for the ' T ' piece and drill a hole in it , then place the probe in and do up the nut using a silicone washer . I did it this way and have not had a leak at all . Very simple .

Cheers
Leachim

 

[Tim F]

Awesome tip, cheers. I've been wondering the best way to do it. So a washer with hole just big enough for the probe so it gets squeezed shut when you do the cap up?