How to build a Brewing Control Panel - HERMS 240V 30 AMP

[augiedoggy]

That looks like plastic

Yes correct its the same enclosure many suppliers like high gravity and now brua supply have been using for years... Its designed to be a watertight electrical box.
Much easier to cut the holes in than steel as well.

Do you not trust your wiring or components in a plastic electrical box? its the same stuff the pids, switches, ssrs and contactors are all made of as well as many other more complicated electronic devices like stereo, printer, tvs, projectors, coffee makers ... well pretty much any appliance these days.

In all my years here I havent seen one issue with a plastic enclosure yet.

 

[MikeSkril]

Yes correct its the same enclosure many suppliers like high gravity and now brua supply have been using for years... Its designed to be a watertight electrical box.
Much easier to cut the holes in than steel as well.

Do you not trust your wiring or components in a plastic electrical box? its the same stuff the pids, switches, ssrs and contactors are all made of as well as many other more complicated electronic devices like stereo, printer, tvs, projectors, coffee makers ... well pretty much any appliance these days.

In all my years here I havent seen one issue with a plastic enclosure yet.

Better spending 15 minutes on cutting metal. A metal box would never melt like that.

 

[augiedoggy]

Better spending 15 minutes on cutting metal. A metal box would never melt like that.

I would think, niether would a properly built and gfci protected box. Good grief was there anyone even around to let that go that long?

 

[MikeSkril]

I would think, niether would a properly built and gfci protected box. Good grief was there anyone even around to let that go that long?

I have no idea, I got that off the net but did not read the full story.
Mistakes happens, you'll never know.

I don't always stay near my panel when using it. Usually, I’m away for one hour while heating strike water or mashing. I like peace of mind and I'm feeling better having the SSR's within a metal box...considering that the box was less than $20.

 

[TheMadKing]

So I'm going to necro this thread with a question.. @doug293cz you might be able to answer this better than anyone

Wouldn't a better design be:

Install a switch that changes which PID controls the heating element in the HLT. So during Strike/Sparge it's controlled by the HLT PID, but during mash its controlled by the Mash PID.

That way you are controlling your heat source for your mash based directly on the mash temps.

Is there some reason not to do this? Or is the temperature differential between HLT and the mash in a HERMS system just too small for that to matter?

I just don't want to end up in a situation where I'm guestimating how many degrees higher I need to set my HLT PID to get my mash temp where I want it for every brew.

 

[guillaume]

So I'm going to necro this thread with a question..

That way you are controlling your heat source for your mash based directly on the mash temps.

Is there some reason not to do this? Or is the temperature differential between HLT and the mash in a HERMS system just too small for that to matter?

In my opinion, and that's what I do, controlling the mash temp by heating the HLT and controlling the temperature inside the HLT to my target mash temp is safer. If you heat it to a couple degrees more, and send (for example) 170F wort back in the mash, you might kill off the enzymes. It might be too slow for step mash though, I'm only doing single mash temp so I don't know.

From my experience, I set my HLT to target mash temp and monitor the mash temp with another pid that controls nothing (really, it's just there to see the temperature of the mash) and everything stays within 0.5F of target.

 

[TheMadKing]

In my opinion, and that's what I do, controlling the mash temp by heating the HLT and controlling the temperature inside the HLT to my target mash temp is safer. If you heat it to a couple degrees more, and send (for example) 170F wort back in the mash, you might kill off the enzymes. It might be too slow for step mash though, I'm only doing single mash temp so I don't know.

From my experience, I set my HLT to target mash temp and monitor the mash temp with another pid that controls nothing (really, it's just there to see the temperature of the mash) and everything stays within 0.5F of target.

Thanks! That answers that. I do intend to step mash, but if the temperature lag between the HLT and the MT is only 0.5 degrees it should still work just fine

 

[doug293cz]

So I'm going to necro this thread with a question.. @doug293cz you might be able to answer this better than anyone

Wouldn't a better design be:

Install a switch that changes which PID controls the heating element in the HLT. So during Strike/Sparge it's controlled by the HLT PID, but during mash its controlled by the Mash PID.

That way you are controlling your heat source for your mash based directly on the mash temps.

Is there some reason not to do this? Or is the temperature differential between HLT and the mash in a HERMS system just too small for that to matter?

I just don't want to end up in a situation where I'm guestimating how many degrees higher I need to set my HLT PID to get my mash temp where I want it for every brew.

Sorry I was busy yesterday and didn't get a chance to respond. @guillaume is doing things correctly. Here's why:

If you try to use a mash temp probe to control the HLT temp, you have a long time lag between when the mash temp responds to the higher HLT temp. The effect of the time lag is to allow the HLT water to heat up way beyond the MLT target temp before the PID shuts down heating to the HLT. This then results in overheating the MLT while the HLT cools back down. If you let this system run for a long time, you tend to get wide oscillations in temp that have a period of many minutes to hours. To get around this, you have to slow down the response of the PID+heater to the point where the time lag in temp response is a fraction of the heat up time of the PID+heater. Then you get extremely slow response if you want to change temps. As guillaume noted, the wort in the HEX could get hot enough to denature the enzymes when the HLT overheats.

You could add an over temp shutoff to the HLT heater, that would be set a few degrees above the mash temp, but then the system will act just like an HLT temp probe controlled system with the HLT temp set a couple of degrees hotter than the MLT target.

If you really want a fast heat up response in a HERMS system, without significant overshoot, you would need to use a non-PID algorithm that used two temp probes, and accounted for the lag time in the system. A really good algorithm could continuously measure the response time and adjust the algorithm parameters to compensate in real time. The algo would also limit max HLT temp to minimize denaturing. There is an algorithm something like this in the BrewPi control software, but IDK if it handles the max HLT temp limit requirement.

Brew on

 

[TheMadKing]

Sorry I was busy yesterday and didn't get a chance to respond. @guillaume is doing things correctly. Here's why:

If you try to use a mash temp probe to control the HLT temp, you have a long time lag between when the mash temp responds to the higher HLT temp. The effect of the time lag is to allow the HLT water to heat up way beyond the MLT target temp before the PID shuts down heating to the HLT. This then results in overheating the MLT while the HLT cools back down. If you let this system run for a long time, you tend to get wide oscillations in temp that have a period of many minutes to hours. To get around this, you have to slow down the response of the PID+heater to the point where the time lag in temp response is a fraction of the heat up time of the PID+heater. Then you get extremely slow response if you want to change temps. As guillaume noted, the wort in the HEX could get hot enough to denature the enzymes when the HLT overheats.

You could add an over temp shutoff to the HLT heater, that would be set a few degrees above the mash temp, but then the system will act just like an HLT temp probe controlled system with the HLT temp set a couple of degrees hotter than the MLT target.

If you really want a fast heat up response in a HERMS system, without significant overshoot, you would need to use a non-PID algorithm that used two temp probes, and accounted for the lag time in the system. A really good algorithm could continuously measure the response time and adjust the algorithm parameters to compensate in real time. The algo would also limit max HLT temp to minimize denaturing. There is an algorithm something like this in the BrewPi control software, but IDK if it handles the max HLT temp limit requirement.

Brew on

Thanks for the great explanation as always!

 

[stevehaun]

In my opinion, the simplest way to control your mash temp with a herms is to put the "controlling" temp probe at the top of the mash tun and put the "monitoring" temp probe at the mash tun drain. Thus, you control the temp of wort as it returns to the top of the mash and monitor the temp of the wort as it leaves the bottom of the mash. To me, this is the most direct way of controlling mash temp. Controlling with the temp probe in the mash leads to the issues with lag times and overshoot and controlling with the temp probe in the HLT requires extrapolation of mash temps from HLT temps.

 

[doug293cz]

In my opinion, the simplest way to control your mash temp with a herms is to put the "controlling" temp probe at the top of the mash tun and put the "monitoring" temp probe at the mash tun drain. Thus, you control the temp of wort as it returns to the top of the mash and monitor the temp of the wort as it leaves the bottom of the mash. To me, this is the most direct way of controlling mash temp. Controlling with the temp probe in the mash leads to the issues with lag times and overshoot and controlling with the temp probe in the HLT requires extrapolation of mash temps from HLT temps.

View attachment 616219

Yes, controlling with a probe in the mash stream returning from the HEX will certainly reduce the time lag responding to increases in HLT temp, and eliminate the possibility of overheating the wort. It would be interesting to see the temp deltas between in HLT and in mash return probes. I suspect that the deltas would be a fraction of the deltas between HLT and bulk mash, and wonder if there is any significant difference in control between the HLT and stream placements.

Brew on

 

[Brewswanger]

I know this is an old thread but Mike, I was wondering if you had a hard copy of your instructions? I am 90% through my build and noticed today that your instructions are no longer on your site. Thanks.