Planning an E-HERMS build - questions

[scottsr123]

I'm looking to upgrade my brewing setup to an E-HERMS. To save money, I'm trying to re-use some things I already have, while leaving the door open to expand some of the hardware (kettle, MLT, HLT) at a later date and still be able to use the electronic controls.

Here's what I'm looking at for a PID:
http://www.auberins.com/index.php?m...ducts_id=239:1996b77e84fe9a8bc5475bed773a021e

With this SSR:
http://www.auberins.com/index.php?main_page=product_info&products_id=9

And this thermocouple:
http://www.auberins.com/index.php?main_page=product_info&products_id=266

I'll be using a March pump to move the liquids. For now, I'm planning manual control of the pump(s).

I'm planning to heat water with a 110V heating element, but want to upgrade later to 220V. The thermocouple will go in a thermowell in my MLT.

I'll be manually firing my BK with a gas burner.

Am I on the right track? Improvement suggestions?

Thanks!

 

[BadNewsBrewery]

1: you may get more responses in the Electric sub-forum, at least on your electric questions.

2: I use the same PID, the 2451. Should work for you.

3: why the K type in a thermowell? Why not an RTDs directly inline with your MLT output so you're measuring the temperature of the wort as you send it to the HEX?

4: How big (gallons)? 120 will take a while to get up to temp in the HLT so you may want to pre-heat your water with the gas. If you plan to go to a 220v system in the future, get a bigger SSR now to help with heat dissipation, 40a would be good.

5: without two pumps or automatic means to stir the HLT, make sure you mix it from time to time to prevent thermal stratification around the HEX. Not sure how big of an issue it'll be but something to monitor.

Looks like you're on the right path.
-Kevin

 

[scottsr123]

Thanks, Kevin!

Please tell me more about the RTD; it's been a loooooong time since I've messed much with electronics, and have very little experience with temp probes.

I'll take your advice and go with the 40A SSR, as the cost difference is minimal.

I'm making 5 gallon batches, and planned to pre-heat water on the gas burner, use the HEX to maintain mash temp, then to raise from ~152 to 170 for mash out and use the 170 degree water to sparge.

Good point about circulating the water in the HEX; I have a small pond pump I might try to see if it will survive the temp. Ultimately, I'll buy another March.

 

[BadNewsBrewery]

I don't have any technical know-how on temp probes. The RTDs have threaded bases that can be installed directly into the liquid without a thermowell. I am installing mine in a T off the outlet before the pump quick disconnect.

Your element should be fine for your application. What wattage ate you thinking? Another way to save some costs is to get a 5500w 240v element and run it at 120v which will give you a 1375w heater that would be easily upgraded in the future by switching out the wiring.
-Kevin

 

[scottsr123]

Thanks!

I'll look into the RTD probes; sounds like a much better option. I am planning on using a 5500W 240V element, initially operating at 110V.

 

[theonetrueruss]

I have a thermowell on the output of my herms coil and also in the hlt itself. That lets me easily move my probe between the two depending on what stage I am on.

 

[scottsr123]

I have a thermowell on the output of my herms coil and also in the hlt itself. That lets me easily move my probe between the two depending on what stage I am on.

Might you have a couple pictures of this that you could share?

Thanks!

 

[scottsr123]

I have a thermowell on the output of my herms coil and also in the hlt itself. That lets me easily move my probe between the two depending on what stage I am on.

I'm also wondering - is it possible to install two NPT sensors, one at the outlet of the HEX and one in the HLT (to measure water temp), and use a switch between the probes and the PID controller to select which probe is in use?

Anyone ever try this? Would the probes still read accurately if configured in this manner?

 

[BadNewsBrewery]

You'd need a switch that could switch all three poles at once, I'm sure it's out there if you looked. The only other issue I can think of is that the PIDs 'learn' the system in time, so if you are using one PID to control one element using two temperature sensors, it will never quite learn the system.

 

[scottsr123]

Thanks, BadNews.

Something like this?

 

[BadNewsBrewery]

That would work I suppose. You'd have to link the output side together. So your NO input would be RTD1, your NC input would be RTD2, and the outputs from both would be jumpered to run to the PID. The only concern I'd have - is there ever a situation where, in the process of switching, both the NO and NC terminals are momentarily closed, such that you're getting input from BOTH RTDs, and also cross-signaling the RTDs? And, even if this could remotely happen, would it be an issue? Would the PID or RTDs have trouble?

 

[theonetrueruss]

Might you have a couple pictures of this that you could share?

Thanks!

no time for pics right now... I'm not actually using a PID, just a digital johnson controls temp controller pinned out for heating. It controls power to my SSR. I get about 1 degree of fluctuation but I feel that is quite adequate for now.

the thermowell on the output is connected to a T so the end to the side is the output of the coil and the other has a 2 inch thermowell. Enough for the probe to go in the flow of the wort.

The thermowells let me move the probe back and forth.

Eventually I am planning a nice control panel with 3 pids and a switch to determine which one controls the element. Plan on reading from HLT, HERMS output and from MLT. This plan is at leasy a year off though.. other projects are ahead of it.

 

[scottsr123]

Okay, so I'm going to use an Auber 2451 PID to control a 5500W element, initially at 110V but want to go to 220V, to run my HERMS vessel. I'll use a 40A SSR to power the element so that I have plenty of capacity for later expansion. I'll put the PID, SSR and some switches in a small control box.

What would you all recommend for a heat sink? They have both internally and externally mounted models on the Auber site, but the internally mounted models look like they would require a big control box. I'm leaning towards external.

Any advice?

 

[milesvdustin]

Wouldn't the thermocouple just installed in the hlt be sufficient for the mash and then mash out temp control? I would imagine if there is a pump or stir motor moving the water then the mash temp would equal your hlt temp while recirc, and it would keep the temp up while sparging. Or is putting the probe on the coil output necessary?