Got stuck on my electric setup.. need advice

Ok so I started down the path to a partial electric setup here:

https://www.homebrewtalk.com/f51/looking-into-herms-system-heres-my-approach-s-350658/

Well I didn't do my research properly and discovered (luckily, the easy way by stumbling across it on the forums) that the Johnson A419 is only rated up to 15 or 16 A, which is not enough obviously if my 2000w element is pulling 16.3 A.

The way I see it, I have 2 'easy' options here:

1.) Buy a 1500w element that will work with my Johnson A419 and save the 2000w element for a rainy day when I can try to go full electric. My 2 questions here are: should the 1500w element be strong enough to maintain my mash temps at 154? I would think so (I'm not that worried about how long it will take to get up to that point, I can always heat with my propane burner, I'm really only worried about the mash temps). Also, if I try to go full electric, will 2000w be enough to maintain a rolling boil? I usually have 6.5-7 gallons at the start of my boil. Again, I am fine with using the stove and the element to get it up to boiling, but would really like to only use the element during the boil. Can this be done?

2.) Buy a PID that can handle the amps from the 2000w element. I plan on converting a mini fridge into a ferm chamber anyway so my johnson A419 wouldn't go to waste, but I had hoped to just use the controller for both purposes.

I'd prefer to go with option 1 if it will work out. What do you guys think?

I think to control an electric element you will be much happier purchasing a PID controller and using that in conjunction with an SSR. Just my opinion, but the way the PID's control elements is a much better solution than using a standard temperature controller. Maybe look at building a little RIMS tube?

You could add an SSR and then use the A419's relay contact to provide some low voltage DC power say from an old cell phone transformer to the SSR, which would then control your heating element. Or an interposing relay. If you don't have a lot of thermal mass in the heating element, which it probably doesn't, it shouldn't overshoot too much.

Sublime8365 said:

2.) Buy a PID that can handle the amps from the 2000w element. I plan on converting a mini fridge into a ferm chamber anyway so my johnson A419 wouldn't go to waste, but I had hoped to just use the controller for both purposes.

Click to expand...

There are no PIDs with internal relays that can handle that amperage(2000w=16A @120v). Most are rated for 2-3A. You would need a SSR or a contactor that your PID would control.

Thanks everyone for the input!

I'll definitely invest in an SSR.

porcupine - I think I'm going to look into your suggestion first because it allows me to avoid purchasing a PID for the time being. What type of volts/amps should I be looking for in an old cell phone charger? What would be the potential disadvantages of doing this versus a PID?

Thanks!

Whatever voltage range your SSR would accept. Most seem to say 3VDC to 32VDC. Pretty much any wallwart, old cell phone charger, etc will fall into that range. The SSR's don't need a ton of current to fire, a cell phone charger would have plenty of current available. You do need the heat sink with your SSR though.

With a PID you will get better control basically IF it is tuned properly. You can get less temperature variation and it can be tuned to pretty much eliminate overshoot if it is tuned to the system. The Johnson is simply an on/off linear controller based on the setpoint with what appears to be basically a hysteresis option, it does not use PID control. But with the Johnson you could probably still maintain the temperature within about 3 deg F range.

Thanks. Would I need a heat sink with the SSR regardless if I go with the PID or Johnson Control.

And when you say within 3 degree range, do you mean +/- 3 (eg 151-157 degrees) or +/- 1.5 (eg 153-156)?

Sublime8365 said:

Thanks. Would I need a heat sink with the SSR regardless if I go with the PID or Johnson Control.

And when you say within 3 degree range, do you mean +/- 3 (eg 151-157 degrees) or +/- 1.5 (eg 153-156)?

Click to expand...

You will need a heatsink for the SSR either way.

If you set your mash temp for say 155F you could have a variance down to 152-158. 3F in either direction from your mash temp.

FWIW, I'd recommend a PID. They are much more accurate and you will save time and frustration in the long run doing this the "correct" way the first time.

Yeah it sounds like the PID is the way to go here.

I'm looking at buying the following unless you have recommendations for better/cheaper alternatives:

http://www.auberins.com/index.php?main_page=product_info&products_id=77

http://www.auberins.com/index.php?main_page=product_info&products_id=30

http://www.auberins.com/index.php?main_page=product_info&products_id=3

I'm just estimating a three degree range with the Johnson based on how I have seen my behave. I am not saying it would be +/- 1.5. I think it would be more like +2 -1. Depending on how you set it up, it will come on above or below the setpoint, but the idea being it does not turn off until it reaches at least the setpoint, and then there is a bit of a delay time in it sensing the temp, so generally the temp it senses will continue rise a bit after it turns off, especially if the heating element has a lot of thermal mass (not likely the case here). It's just the response of the system. The Johnson is simple on/off control. Most of the PID's have a tuning sequence. Essentially it is analyzing the step response of the system, and if it is LTI (linear time invariant) which something like this would be, then it has a model of the system and can control it very accurately because in effect it can predict what will happen in the future based on the output it has been giving and the error signal.

I guess I'll need a temp sensor too.. how about this:

http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=27

Sublime8365 said:

Yeah it sounds like the PID is the way to go here.

I'm looking at buying the following unless you have recommendations for better/cheaper alternatives:

http://www.auberins.com/index.php?main_page=product_info&products_id=77

http://www.auberins.com/index.php?main_page=product_info&products_id=30

http://www.auberins.com/index.php?main_page=product_info&products_id=3

Click to expand...

For the PID that is definitely the way to go, for the SSR's you can pick them up cheaper on eBay if you want. You will likely have to wait a few weeks (slow boat from China) but if you're not in a hurry you can save a bit of cash.

http://www.ebay.com/itm/40A-SSR-Solid-State-Relay-Heat-Sink-DC3-32V-Control-AC24-480V-/120968339169?pt=LH_DefaultDomain_0&hash=item1c2a465ee1

Sublime8365 said:

I guess I'll need a temp sensor too.. how about this:

http://www.auberins.com/index.php?main_page=product_info&cPath=20_3&products_id=27

Click to expand...

Using this particular PID you can also use an RTD Probe. I'd pick up one of the liquid tight ones and mount it directly to the kettle. Something like the link below. If you have a sightglass mounted with a "T" you can put a 6" probe in there and get accurate temp readings, but if you mount it directly to the kettle a 4" should be more than sufficient.

http://www.auberins.com/index.php?main_page=product_info&cPath=20_15&products_id=85

And yet again, if you don't mind doing a little searching you can find PT100 RTD probes on eBay much cheaper.

http://www.ebay.com/itm/Temperature-Sensors-RTD-PT100-with-Terminal-Head-/251151545403?pt=LH_DefaultDomain_0&hash=item3a79cc743b

Also Amazon stocks and sells SSR's, I have a few of theirs, it's convenient if you have Prime and need them quickly.

Thanks for the help guys!

I ordered my SSR and heat sink last night and I'm shopping around for the PID.

Currently I'm looking at this one:

http://www.ebay.com/itm/PID-Digital...614?pt=LH_DefaultDomain_0&hash=item337ab454b6

As you can see, it comes with a k type thermocouple. I can't really tell by the pic on the thermocouple - do I need to buy a separate probe to screw into that or is that just a small probe?

Sublime8365 said:

Currently I'm looking at this one:

http://www.ebay.com/itm/PID-Digital...614?pt=LH_DefaultDomain_0&hash=item337ab454b6

As you can see, it comes with a k type thermocouple. I can't really tell by the pic on the thermocouple - do I need to buy a separate probe to screw into that or is that just a small probe?

Click to expand...

I don't own one of those. I bought Aubers. There have been threads on here before that do not speak highly of those "pseudo-Aubers from China", including one a couple of days ago. An often-repeated comment is something to the effect of "I wish I'd spent the extra $20 and bought an Auber the first time". This influenced my thinking. I must admit a leaning that way, anyway. Unless it's a single use tool, I'd rather buy a quality item once, instead of getting the bargain one first, and the quality one later. It's a lesson I periodically get re-taught by life, at some cost.

Here's one of those threads: https://www.homebrewtalk.com/f170/ebay-pid-353583/

Go with the Auber SYL-2352 that I linked to, it's worth the extra coin.

Sublime8365 said:

Thanks for the help guys!

I ordered my SSR and heat sink last night and I'm shopping around for the PID.

Currently I'm looking at this one:

http://www.ebay.com/itm/PID-Digital...614?pt=LH_DefaultDomain_0&hash=item337ab454b6

As you can see, it comes with a k type thermocouple. I can't really tell by the pic on the thermocouple - do I need to buy a separate probe to screw into that or is that just a small probe?

Click to expand...

BTW this model is not an SSR model...

Ok I'm just going to play it safe and go with the Auber PID.

Now for the probe. I've looked into your suggestions but I guess I want to figure out where I'm going to place the probe first.

I'm going to be building a herms system where the wort will be flowing from my cooler/mash tun, through a copper coil previously used as an immersion chiller that will be sitting in a SS pot/HLT, then back into the mash tun of course. Wouldn't I want to put the probe at the output of the tube coming out of the coil? That would give me the reading of the wort going back into the tun. Does that sound right?

The probe should go into the HLT water. If you put it at the outlet of the coil the HLT water will get too hot and will take forever to cool down. Start with the setpoint a bit higher than needed, then reduce to desired setpoint as the whole system comes up to temp.

I would have two probes. Have one in the hlt to control the temperature of the water and another on the output of the HERMS coil to measure the temperature of the wort. That way you can adjust the hlt temperature as needed.