Wiring Diagram Sanity Check

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I am building an electric HLT, using a 160 qt cooler and water heater elements. I would like feedback on the attached design; I have some amateur wiring experience (service to my wood shop, rewiring motors, etc), but am certainly not a pro electrician.

Are there any critical wiring mistakes in this diagram? I have not decided on a particular temp. Controller or relays yet, so if any of you have suggestions, I'm receptive to those as well. Not stated in the drawing, but the project box will obviously be grounded as well.

Thank you all in advance!

PS: using 8ga with no neutral for the 40A, 240V circuit. I already have the receptacle installed in my garage. Probably 14ga for the 120V parts.

image.jpeg
 
I am building an electric HLT, using a 160 qt cooler and water heater elements. I would like feedback on the attached design; I have some amateur wiring experience (service to my wood shop, rewiring motors, etc), but am certainly not a pro electrician.



Are there any critical wiring mistakes in this diagram? I have not decided on a particular temp. Controller or relays yet, so if any of you have suggestions, I'm receptive to those as well. Not stated in the drawing, but the project box will obviously be grounded as well.



Thank you all in advance!



PS: using 8ga with no neutral for the 40A, 240V circuit. I already have the receptacle installed in my garage. Probably 14ga for the 120V parts.


Looks OK, you really only need to control one 120v leg of the 240v heater circuit. Might save some money. Just make sure you make your connections secure and not with a cheap crimp tool.
 
Why not run the temp controller off 240 and dump the 120 completely. Also you are going to want a Ssr in there for sure. You will burn out the contactor quickly if you are using that to throttle your elements. It's a good idea to have them as a means to disconnect an element though.
 
Why not run the temp controller off 240 and dump the 120 completely. Also you are going to want a Ssr in there for sure. You will burn out the contactor quickly if you are using that to throttle your elements. It's a good idea to have them as a means to disconnect an element though.

If this is a PID type controller, I would share your concern..... If something like an STC 1000, it won't be snapping the contactor off and on that much. A PID is completely inappropriate to use with a contactor

You might just use ordinary water heater thermostats. After all an HLT is just a water heater. In fact I have several times advocated just using a small water heater for the job, and plumbing it in permanently. You can buy commercial water heater thermostats that are adjustable up to 170F. I use hot water right out of my water heater (gas) for mashing, and a friend across the street has his set at 170, which results in water that hits the mash tun at exactly the correct temp for strike water............. Keep it simple! With all the parts you are putting together, you could easily go out and buy a brand new water heater for the job. And of course nobody wires a water heater to a GFI.

H.W.
 
Looks OK, you really only need to control one 120v leg of the 240v heater circuit. Might save some money. Just make sure you make your connections secure and not with a cheap crimp tool.
I don't doubt you. I have seen other diagrams set up as you describe: using the relay on only one leg of the 240V circuit. I don't understand how that can completely shut off the flow of energy to the element...wouldn't we still get 120V of juice going through the other hot leg? Could you explain how that works? I would do it if I could understand it a little better.

Thank you for the awesome feedback! This is exactly what I need.
 
Looks OK, you really only need to control one 120v leg of the 240v heater circuit. Might save some money. Just make sure you make your connections secure and not with a cheap crimp tool.
I don't doubt you, as I've seen other diagrams as you describe: with a relay on just one hot leg of the 240V. I'm afraid to do this because I don't fully understand how that's safe. Wouldn't we still get 120V of juice to the element through the other hot leg? Can you (or anyone else on this thread) explain where I'm wrong?

Thank you for the feedback! This is just what I needed.
 
Why not run the temp controller off 240 and dump the 120 completely. Also you are going to want a Ssr in there for sure. You will burn out the contactor quickly if you are using that to throttle your elements. It's a good idea to have them as a means to disconnect an element though.
Are you saying to get a temperature controller that runs off 240V, or are you suggesting I run one hot, 120V leg from the 240V circuit through the controller to power it? Would this create an unbalanced load? Would I risk frying the controller in that situation?

Sorry for all the questions. I'm all for simplicity, but I want to make sure I fully understand it before I commit.
 
If this is a PID type controller, I would share your concern..... If something like an STC 1000, it won't be snapping the contactor off and on that much. A PID is completely inappropriate to use with a contactor

You might just use ordinary water heater thermostats. After all an HLT is just a water heater. In fact I have several times advocated just using a small water heater for the job, and plumbing it in permanently. You can buy commercial water heater thermostats that are adjustable up to 170F. I use hot water right out of my water heater (gas) for mashing, and a friend across the street has his set at 170, which results in water that hits the mash tun at exactly the correct temp for strike water............. Keep it simple! With all the parts you are putting together, you could easily go out and buy a brand new water heater for the job. And of course nobody wires a water heater to a GFI.

H.W.
Those are great suggestions! I will check on my space requirements for a separate hot water heater. Failing that, I think a PID may be a little too sophisticated for what I'm trying to do here, so a regular contact relay could suffice. As far as the water heater thermostats ar concerned...I'll need to do some more research on that. My water heater just has an adjustment screw (not sure about the accuracy on that) and tops out at 150F. It would be nice if I found a digital one that can handle 170 - 180F...could be the simple, elegant solution I'm looking for.
 
The diagram is the wrong way to use a contactor, you need a ssr there. I can post an updated diagram later tonight
 
If you run the neutral you will have 120V available without a second plug. Most PIDs will run off of both 120V or 240V. But most fans need 120V. So I ran a neutral in my box and run the cooling fan and PID off of one of the hots and neutral. Works fine. I also skipped the contactor (relay) and switch and just use the spa panel breaker. But I am cheap.
 
And yeah if making this for a mash controller use a PID and SSR. Not that expensive. For a boil either a PID/SSR and a series SSVR or a PID with a "manual mode" Pseudo Pwm mode such as the MyPin TD4 (not TA4).
 
You haven't bothered to specify what you are using for a thermostat. There is nothing fundamentally WRONG with using a contactor or using it like this unless you are using a PID controller... as opposed to an STC 1000 or something of that sort. A PID will cycle rapidly, and a contactor will not survive that. Everybody here seems to be in love with PIDs. We are NOT building space shuttles here..... we are talking about building a WATER HEATER. That's what an HLT is...... just a water heater. Let's keep it simple.

240 or 220 is it is more popularly called requires L1 and L2 to have a circuit, just as 120 volt AC requires a neutral There is no safety issue with switching a single leg..... That's what your water heater does.

Clearly you don't understand electricity.. buy a book

What we are doing is heating water........ How hard can that be? As a child, we had a tank on the back of our wood cook stove........ How complicated can we make a simple task? We are just making BEER, and beer is NOT a new high tech product, it's been around for thousands of years.


H.W.
 
You haven't bothered to specify what you are using for a thermostat. There is nothing fundamentally WRONG with using a contactor or using it like this unless you are using a PID controller... as opposed to an STC 1000 or something of that sort. A PID will cycle rapidly, and a contactor will not survive that. Everybody here seems to be in love with PIDs. We are NOT building space shuttles here..... we are talking about building a WATER HEATER. That's what an HLT is...... just a water heater. Let's keep it simple.

240 or 220 is it is more popularly called requires L1 and L2 to have a circuit, just as 120 volt AC requires a neutral There is no safety issue with switching a single leg..... That's what your water heater does.

Clearly you don't understand electricity.. buy a book

What we are doing is heating water........ How hard can that be? As a child, we had a tank on the back of our wood cook stove........ How complicated can we make a simple task? We are just making BEER, and beer is NOT a new high tech product, it's been around for thousands of years.


H.W.
Some of my comments aren't making it to this thread, so Sorry for the confusion: I have not decided on a temperature controller yet, though it seems that I need to decide on one, since that has a bearing on the type of relay used.

I am leaning toward a simpler device, probably an STC 1000 as you mentioned.
 
Regardless of what you use, i wouldn't ever recommend using a contactor in place of a SSR. They should be used for two distinct different purposes. SSR's for directly controlling power into your elements as they can cycle quickly, and contactors hooked up to switches to be toggled on and off by hand to control where power is even allowed to go.

With how slow a STC1000 responds i personally wouldnt use it to control even a HLT, the fastest you can have it cycle is once a minute and depending on what volumes your working with and your ambient temp you can easily drop a few degree's in 1 minute of the HLT water recirculating.

This also allows you to get away from using a more expensive 40A(not even sure where you buy these?) switch. You never want your active high current actually flowing through your switches, thats how you get electrocuted. You use the switches to control your Contactor's coil pins which use a very very small amount of current which in turn allow your main hot voltages through.

I would do something like this...Overall it adds only like $20 to your existing build, although it might end up being the same cost since i have no idea how expensive a 40A switch is. One 2 selector toggle switch to control the contactor coils to allow the 240V in. I am unsure what the yellow and blue wires were, i assume your SSR control output + and -, so i wired those to the SSR control pins. In reality on the 2 selector toggle its not coming in the left and out the right, the switch has two NC sides. You wire it up the input and output of one NC side(say the right) so when your switch is off(To the left) there are no wires even plugged in so no power gets to your coil but when you turn the switch to the right it opens and allows the hot(red) voltage through to your coil, completing the required 240V circuit with the black hot wire and activating the contactor allowing the red and black hot voltages through to your SSR which is then cycled on and off by your controller via its input pins. Hopefully that makes sense ;) Oh and i'd buy two and use the same 2 position selector switch for your 120V input as well.

MkoVHuY.jpg
 
To answer the 240 or 120-120 per leg, the device when the SSR is off will still have 120 unswitched and 120 floating on the SSR controlled leg.

Since you need a circuit (2 or more wires) the SSR is opening the circuit and stopping the flow of current. You could do both legs but its unnecessary.

Please realize that an SSR is NOT a disconnect!!! It's not going to protect you from getting shocked while working on the element!!!! Please unplug or turn off your breaker feeding this before working on it! I like using a contactor before the SSR, that way you can have a real emergency off if you use a red mushroom push button at your control panel, might be faster than unplugging under load or running to your breaker panel if bad things are happening.
 
An STC is a non linear "bang bang" controller that makes no effort to predict over and under shoot. Because of this it is only accurate to a couple of degrees. This is actually pretty optimal for a refrigerator because it can't cycle in less than minutes and you want a certain amount of over and under shoot. For a mash tun it isn't ideal. For $20 extra, why wouldn't you want something that can predict over and under shoot and hold to about 1°F. Otherwise, just use a cooler. Now for boil, you can't do a linear prediction on a non-linear phase transition, so that is why manual control is needed. On an element that draws 18-20A hot switching limits the life of mechanical relays (contactors) and SSR are actually cheaper and more desirable than a mechanical relay anyway. Since a heating element is a resistor, switching fast is a non issue for the device. In the case of a PID, you can get very accurate Pt100 RTD sensors that are an order of magnitude better than the NTC resistors used in the STC controllers. So this is why most people will use a PID for brewing and a STC for fermentation chambers and keezer...
 
By the way, I use the breaker on my spa panel instead of a contactor for my on and off but it is in a unattached box next to the control panel. If you wanted a big emergency off button it is simple enough to use a resistor to cause a ground fault and trip the spa panel. So a contactor isn't 100% needed.
 
By the way, I use the breaker on my spa panel instead of a contactor for my on and off but it is in a unattached box next to the control panel. If you wanted a big emergency off button it is simple enough to use a resistor to cause a ground fault and trip the spa panel. So a contactor isn't 100% needed.


I absolutely hate that resistor idea. If it were a good idea you would see it used in industry. It works as a test button only. By doing that you are outside the rated operation of the GFCI and limiting the lifespan as well.
 
That is exactly how the test button on the GFCI functions. Literally the same circuit. If the breaker isn't crap it shouldn't limit its life either. I switch off the breaker on my setup after turning down the series connected SSVR in my setup so I will never have any issues anyway.. In an emergency I would just hot switch the breaker off or hit the test button.

Edit--

As an Electrical engineer who as a test engineer actually designed a few rack panel power distribution units.. After thinking about it, an emergency off is not supposed to be used as a main power off anyway! The modern PDUs I have worked with used trip wired breakers and not always on contactors (relays) like I see most homebrewers use. They older units did use relays but always latching ones so power wasn't continually supplied to them. The trip on a PDU is daisy chainable.

Turning it around I would argue not tripping the GFCI on an emergency off button is LESS safe as there is still 240V on the contactor control switch and in the box. Luckily it doesn't matter in practice because what makes that hazardous in a closed box would be if water got into the box. But then the GFCI would trip anyway.

But just because an electrician can't do it do not automatically assume that it isn't done in product or is automatically unsafe.
 
Regardless of what you use, i wouldn't ever recommend using a contactor in place of a SSR. They should be used for two distinct different purposes. SSR's for directly controlling power into your elements as they can cycle quickly, and contactors hooked up to switches to be toggled on and off by hand to control where power is even allowed to go.

With how slow a STC1000 responds i personally wouldnt use it to control even a HLT, the fastest you can have it cycle is once a minute and depending on what volumes your working with and your ambient temp you can easily drop a few degree's in 1 minute of the HLT water recirculating.

This also allows you to get away from using a more expensive 40A(not even sure where you buy these?) switch. You never want your active high current actually flowing through your switches, thats how you get electrocuted. You use the switches to control your Contactor's coil pins which use a very very small amount of current which in turn allow your main hot voltages through.

I would do something like this...Overall it adds only like $20 to your existing build, although it might end up being the same cost since i have no idea how expensive a 40A switch is. One 2 selector toggle switch to control the contactor coils to allow the 240V in. I am unsure what the yellow and blue wires were, i assume your SSR control output + and -, so i wired those to the SSR control pins. In reality on the 2 selector toggle its not coming in the left and out the right, the switch has two NC sides. You wire it up the input and output of one NC side(say the right) so when your switch is off(To the left) there are no wires even plugged in so no power gets to your coil but when you turn the switch to the right it opens and allows the hot(red) voltage through to your coil, completing the required 240V circuit with the black hot wire and activating the contactor allowing the red and black hot voltages through to your SSR which is then cycled on and off by your controller via its input pins. Hopefully that makes sense ;) Oh and i'd buy two and use the same 2 position selector switch for your 120V input as well.

MkoVHuY.jpg

FuzzeWuzze: thank you for your insight and the assistance! Though I appreciate simplicity, I appreciate not being electrocuted or burning the house down more. :) I've actually been eyeing an auber PID (SYL-1512A) instead of the STC-1000 today, so that solves the slow response problem. That PID can run off 240V, which may obviate the need for the 120V input all together. You've also given me a good enough reason/explanation as to why to go with the SSR upstream of the contractor, so I'll definitely be doing that. I will revise the diagram you posted with actual part numbers as I make my selections. I feel like you've gotten me on the right track.
 
An STC is a non linear "bang bang" controller that makes no effort to predict over and under shoot. Because of this it is only accurate to a couple of degrees. This is actually pretty optimal for a refrigerator because it can't cycle in less than minutes and you want a certain amount of over and under shoot. For a mash tun it isn't ideal. For $20 extra, why wouldn't you want something that can predict over and under shoot and hold to about 1°F. Otherwise, just use a cooler. Now for boil, you can't do a linear prediction on a non-linear phase transition, so that is why manual control is needed. On an element that draws 18-20A hot switching limits the life of mechanical relays (contactors) and SSR are actually cheaper and more desirable than a mechanical relay anyway. Since a heating element is a resistor, switching fast is a non issue for the device. In the case of a PID, you can get very accurate Pt100 RTD sensors that are an order of magnitude better than the NTC resistors used in the STC controllers. So this is why most people will use a PID for brewing and a STC for fermentation chambers and keezer...

After thinking about it some more today, I am definitely agreeing with you on this point. My only frame of reference with Temperature controllers is my Ranco on my lagering fridge. Originally assumed this project would be very similar in sophistication, but you've made some good arguments as to why it isn't. I'll look at the Pt100s as you suggested. I don't plan to boil, so a PID without a manual input should do the trick. Thanks for the advice!
 
To answer the 240 or 120-120 per leg, the device when the SSR is off will still have 120 unswitched and 120 floating on the SSR controlled leg.

Since you need a circuit (2 or more wires) the SSR is opening the circuit and stopping the flow of current. You could do both legs but its unnecessary.

Please realize that an SSR is NOT a disconnect!!! It's not going to protect you from getting shocked while working on the element!!!! Please unplug or turn off your breaker feeding this before working on it! I like using a contactor before the SSR, that way you can have a real emergency off if you use a red mushroom push button at your control panel, might be faster than unplugging under load or running to your breaker panel if bad things are happening.

I guess that was my concern: in my mind, I wanted the SSR to act as a disconnect, not as a power regulator, so to speak. I think with the combo of a switch-actuated contactor upstream of the SSR and the GFCI (and the actual wall plug), we should have power disconnect covered. Thanks for the explanation!
 
That is exactly how the test button on the GFCI functions. Literally the same circuit. If the breaker isn't crap it shouldn't limit its life either. I switch off the breaker on my setup after turning down the series connected SSVR in my setup so I will never have any issues anyway.. In an emergency I would just hot switch the breaker off or hit the test button.

Edit--

As an Electrical engineer who as a test engineer actually designed a few rack panel power distribution units.. After thinking about it, an emergency off is not supposed to be used as a main power off anyway! The modern PDUs I have worked with used trip wired breakers and not always on contactors (relays) like I see most homebrewers use. They older units did use relays but always latching ones so power wasn't continually supplied to them. The trip on a PDU is daisy chainable.

Turning it around I would argue not tripping the GFCI on an emergency off button is LESS safe as there is still 240V on the contactor control switch and in the box. Luckily it doesn't matter in practice because what makes that hazardous in a closed box would be if water got into the box. But then the GFCI would trip anyway.

But just because an electrician can't do it do not automatically assume that it isn't done in product or is automatically unsafe.


Well as an electrical engineer, who has designed many many control panels in the nuclear, semiconductor and steel industry, you are wrong about what an EMO does. It's an emergency off, I never said to use it as a disconnect. I said in case something goes wrong it is nice to have a local way to remove power.

You need to understand that tripping the breaker and physically turning it off are two different things.

And the breakers you used for your PDU were probably rated for that use. If they were not and you had an issue at a customer site, I feel sorry for you and the company you work for.
 
Two comments.

Using an SSR for a disconnect is dangerous. The devices only isolate one hot side and often fail shorted when they do fail. So a mechanical setup is a better idea, but flipping the breaker is perfectly fine if it's accessible. I'd make a trip device or a latching relay contactor if I had the GFCI in my main or sub panels.. but I decided to use the Spa panel for two reasons: 1. It's a bit cheaper. and 2. In the Early Spring, Winter and Late Fall I'm going to brew in my basement by the entrance panel. In the Summer, I'd like to go outside to my detached garage so I don't totally humid up the house. So only wanting to do the GFCI once, I made the panel portable and so I can plug other 240V devices in it. Because of that I can run it near the eBIAB kettle.

I worked in RF most of my career, about 1/2 of it as a test engineer, about 1/2 of that hardware, 1/2 software. So my panels are for Spectrum Analyzers, special test equipment, etc. And yes trip breakers are for tripping, obviously.

If you design nuclear reactor panels, you have a whole another level of safety to design to. The real issue here is water and electricity and the GFCI goes a long way to address it. In neither example do I have to worry about a meltdown. I am now working on rotation for the Avionics side and we have to quadruple check everything as well. It makes sense. On the RF side if we did that we wouldn't have been able to be competitive.

I happen to work in Cedar Rapids and know some engineers that designed GFCI and AFCI breakers for Square D (now Schnider Electric). I'll have to ask them if tripping the breakers shortens their life. The limited research I've not doesn't say one way or the other. The button saying "test monthly" though seems to imply otherwise.

But lets say it does... and you use the red button to shut down every time. Instead of 2000 cycles of the breaker you get 1000. It's $55 to replace... not a real problem in the grand scheme of things. And if appropriately sized to just trip the GFCI, the resistance limiting the current to the trip point would be no more dangerous (probably less so) to a person if they caught it than the ground fault situation itself.
 
As it's obviously been decided that a PID will be used rather than something like an STC 1000, the contactor needs to be operated by a master switch....... or dispensed with entirely and replaced with a mechanical switch. I personally prefer knife switches, as they are simple, and 100% reliable. No breaker of any kind should ever be used as a switch..... It's extremely poor practice.

Since we are making an extremely complicated water heater, let's take it a step further, and use a DPDT relay to switch between fast heat and slow heat modes. In fast heat mode, the elements are both on with a full 240 VAC. In slow heat or precision mode, the SSR operates both elements at 120 VAC.

An upper water heater thermostat is used to control the DPDT, and also to provide overheat protection so it shuts everything off if the SSR fails in the on position and overheats the water........ that little red button you've wondered about is the overheat reset button.

This greatly reduces the load the SSR is called upon to handle.



Also forget using a circuit breaker of any kind for a switch. It's extremely bad practice. A master switch should control the contactor.
 
...

Since we are making an extremely complicated water heater, let's take it a step further, and use a DPDT relay to switch between fast heat and slow heat modes. In fast heat mode, the elements are both on with a full 240 VAC. In slow heat or precision mode, the SSR operates both elements at 120 VAC.

...

I like the idea of using a DPDT relay for switching between 120V & 240V. However, I have had no luck finding DPDT relays where both the NO and NC contacts are rated for 30A or higher. Seems like the NC contacts are always rated for significantly lower currents than the NO contacts, and that situation doesn't work for this application. Does anyone know of any reasonably priced DPDT relays that have high current rated NC contacts?

Brew on :mug:
 
I like the idea of using a DPDT relay for switching between 120V & 240V. However, I have had no luck finding DPDT relays where both the NO and NC contacts are rated for 30A or higher. Seems like the NC contacts are always rated for significantly lower currents than the NO contacts, and that situation doesn't work for this application. Does anyone know of any reasonably priced DPDT relays that have high current rated NC contacts?

Brew on :mug:

Whats the benefit of this really? Who cares if my 240V cycles on every 10 seconds to maintain temp or if it was at 120V and just stayed on constantly? I mean if you were doing manual control of an element yes i can see the difference but if my PID controls it who cares?
 
Whats the benefit of this really? Who cares if my 240V cycles on every 10 seconds to maintain temp or if it was at 120V and just stayed on constantly? I mean if you were doing manual control of an element yes i can see the difference but if my PID controls it who cares?

The idea is to have low element power when on during mash temp maintenance in a recirculating direct fired vessel. Less chance of getting the wort too hot in the space around the heater before the temp probe in the recirc loop detects the temp is getting too high.

Brew on :mug:
 
I like the idea of using a DPDT relay for switching between 120V & 240V. However, I have had no luck finding DPDT relays where both the NO and NC contacts are rated for 30A or higher. Seems like the NC contacts are always rated for significantly lower currents than the NO contacts, and that situation doesn't work for this application. Does anyone know of any reasonably priced DPDT relays that have high current rated NC contacts?

Brew on :mug:

can't be specific as to part numbers or models, but I have bought a number of heavy DPDT power relays for use in inverters from WW Grainger. These have all been open frame relays where the points are right out in the open. You can watch the relay trip and the points make contact. Everything is exposed and electrically hot, so you might want to mount it in a box. These are a very rugged simple and high quality product. They lack the "refined appearance" of a relay that is fully enclosed in a pretty plastic housing like an octal base or cube relay that plugs into a socket. They are for commercial / industrial use where they are mounted in a panel, and function is more important than form. A pretty cost effective solution I've found. Of the dozens of these I've used over the last 30 years or so, I have yet to see one fail........That level or reliability is good enough for me!!

H.W.
 
Whats the benefit of this really? Who cares if my 240V cycles on every 10 seconds to maintain temp or if it was at 120V and just stayed on constantly? I mean if you were doing manual control of an element yes i can see the difference but if my PID controls it who cares?

Who cares indeed.................. So long as the SSR handles the load well. Unfortunately SSRs are prone to failure, and require fairly large heat sinks. The less wattage you are handling the more reliable the system will be. I've already said that I would rather use something other than a PID and SSR for this application.


H.W.
 
The idea is to have low element power when on during mash temp maintenance in a recirculating direct fired vessel. Less chance of getting the wort too hot in the space around the heater before the temp probe in the recirc loop detects the temp is getting too high.

Brew on :mug:

Still seems silly when your using a chugger or march pump that is recircing at 7GPM. Your recirc loop shouldnt have any issues detecting that ;)
 
Still seems silly when your using a chugger or march pump that is recircing at 7GPM. Your recirc loop shouldnt have any issues detecting that ;)

If you could reliably run recirc at 7gpm, then I agree. I would be surprised if you could run at flow rates anywhere near that without over compacting the grain bed and/or clogging the pores in the BIAB bag. I don't have any data one way or the other, just a gut feel.

Brew on :mug:
 
If you could reliably run recirc at 7gpm, then I agree. I would be surprised if you could run at flow rates anywhere near that without over compacting the grain bed and/or clogging the pores in the BIAB bag. I don't have any data one way or the other, just a gut feel.

Brew on :mug:

True if we're talking BIAB thats something different, but thats not what OP is making anyways :mug:
 
How about a large schottky diode (about $5-6 from a Mouser/Digi-Key, etc) and a contactor to short the diode out? You'd end up with the same effect as using 120V at the same element.. I've actually read that people have done this on really low end BK setups for boil control..

And all the arguing about the GFCI made me remember this thread when I saw this.. I had to share.. this is what happens when you don't follow the NEC in your build ;)

electician.jpg
 
Regardless of what you use, i wouldn't ever recommend using a contactor in place of a SSR. They should be used for two distinct different purposes. SSR's for directly controlling power into your elements as they can cycle quickly, and contactors hooked up to switches to be toggled on and off by hand to control where power is even allowed to go.

With how slow a STC1000 responds i personally wouldnt use it to control even a HLT, the fastest you can have it cycle is once a minute and depending on what volumes your working with and your ambient temp you can easily drop a few degree's in 1 minute of the HLT water recirculating.

This also allows you to get away from using a more expensive 40A(not even sure where you buy these?) switch. You never want your active high current actually flowing through your switches, thats how you get electrocuted. You use the switches to control your Contactor's coil pins which use a very very small amount of current which in turn allow your main hot voltages through.

I would do something like this...Overall it adds only like $20 to your existing build, although it might end up being the same cost since i have no idea how expensive a 40A switch is. One 2 selector toggle switch to control the contactor coils to allow the 240V in. I am unsure what the yellow and blue wires were, i assume your SSR control output + and -, so i wired those to the SSR control pins. In reality on the 2 selector toggle its not coming in the left and out the right, the switch has two NC sides. You wire it up the input and output of one NC side(say the right) so when your switch is off(To the left) there are no wires even plugged in so no power gets to your coil but when you turn the switch to the right it opens and allows the hot(red) voltage through to your coil, completing the required 240V circuit with the black hot wire and activating the contactor allowing the red and black hot voltages through to your SSR which is then cycled on and off by your controller via its input pins. Hopefully that makes sense ;) Oh and i'd buy two and use the same 2 position selector switch for your 120V input as well.

MkoVHuY.jpg

This took longer than I anticipated, but I think I found the equipment I need. Please let me know if this is out of line. The key is:
1. American LED-gible SW-2837-420 22mm 2 Position Selector Switch: Amazon
2. Packard C240C 2 pole 40A, 208/240V Contactor: Amazon
3. SYL-2352 1/16 DIN PID Temp. Controller (for SSR) [1.89" x 1.89"] Accepts PT100 RTD input to 100mV/20mA. 12V DC output to SSR: Auber
4. MGR-1D4840 40A SSR, 3-32VDC input; 24-480VAC output: Auber

Edit: Of course, I did not include TC wiring or the wiring to the elements. Also will have the heat sink on the SSR

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Yup looks correct.

But is there any specific reason your going with dual 3500W elements instead of just say a single 5500W element?
 
Yup looks correct.

But is there any specific reason your going with dual 3500W elements instead of just say a single 5500W element?

Thanks for all your help again!

Regarding the number of elements: I am not recirculating this water, and the cooler is long and narrow. I figured two shorter elements, staggered on either side, will reduce the likelihood of hot/cold spots.
 
Thanks for all your help again!

Regarding the number of elements: I am not recirculating this water, and the cooler is long and narrow. I figured two shorter elements, staggered on either side, will reduce the likelihood of hot/cold spots.

Sounds good, ill just note you already have 120V coming into your box and one of the cheap P38I plastic pumps for $20 would be better than nothing when your ready to upgrade.

If you havent already bought them i'd just get one 5500W element and a cheap plastic pump. Recirc is a pretty big deal in a HLT to get an accurate temperature reading. Otherwise you will always have hot and cold spots.
 
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