Dual input, 4 element question

I want to run 2x 120V 20A inputs into 2 2352 controllers. Controller 1 is for the HLT and controller 2 is for boil kettle. From each controller I want to run 2x 1650w elements.

I want flexibility to have 2 and only 2 elements getting power at any given time. I want to be able to do 2 elements in HLT, 2 in BK, or 1 in both.

Do I need 4 SSRs or can I accomplish this with 2 SSRs + switches?

Thanks.

I am working on something similar with 2000W elements. I currently have one kettle PID controlled, with two elements run off of SSRs, the other kettle is for boil only and therefore I just run the elements off of switches and relays, and do full power only. So, bottom line I have one kettle PID controlled and one switch controlled. I think if you want to do 4 elements all PID controlled you will need to run four SSR's. I haven't reasoned it completely at this moment but I remember thinking about it in the past and came up with the conclusion you will need 4 SSR's. Maybe I'm wrong on that and someone could offer some additional perspective.

After thinking about this a little more, you could run a single SSR with each controller. But each element would need a relay. So you would split the output of each SSR to two relays, which would be selected by the switches, each element would have its own relay.

Here is info on the relays I am using in my setup:
http://www.auberins.com/index.php?main_page=product_info&cPath=2_31&products_id=250

Also, it sounds like my setup is similar to yours, LMK if you want more info on what I'm doing. I'm about 75% done with mine.

Good luck.

Why couldn't you run two elements off one ssr/contacter, like wall outlets are done. Wire size and supply would need to sized appropriately... Say 2 1500 watts and wire sized for 25 amps, would prob be better to just run a 50 amp 240v.

I think you need an SSR for each element, with the HLT PID driving two SSRs, and the BK PID driving two SSRs. Of course, there may be more elegant ways to do it.

If I understand correctly:

You will have two 120v, 20a feeds, say F1 and F2. These will have to be on different circuits, and you could use 2000w elements with them.

You will have two elements in the HLT and two in the BK, say T1, T2, B1, B2.

You will have a PID for the HLT and a PID for the BK, say PT and PB.

You could use a 20a 3-position switch (or a lower rated switch with an SPDT contactor) to switch F1 between T1 - Off - B1. F1 would have to run to both T1 and B1 (each through an SSR). So you are at most powering 1 element with F1.

Similary, you would do the same with F2 to switch between T2 - Off - B2, so you are at most powering 1 element with F2.

Combining the two switches:
T1 T2 enables both elements in the HLT
T1 Off enables one element in the HLT
T1 B2 enables one element in the HLT and one in the BK
Off T2 enables one element in the HLT
Off Off ensures that no elements are enabled (great safety feature)
Off B2 enables on element in the BK
B1 T2 enables one element in the BK and one in the HLT
B1 Off enables one element in the BK
B1 B2 enables both elements in the BK

There is another way to approach it. If you don't really care to distinguish between, say T1 Off and Off T2, you could reduce this to four states:
T1 T2 enables both elements in the HLT
T2 B1 enables one element in the HLT and one in the BK
Off Off ensures that no elements are on (great safety feature)
B1 B2 enables both elements in the BK

For this, you could run both F1 and F2 through a simple 2-pole, normally open, on/off switch (with a contactor if needed).

After the on/off switch use a 3-position switch to switch between HLT / Split / BK, with three SPDT contactors that closed and opened the appropriate circuits. The load side of these contactors would run to the line sides of the appropriate SSR.

Thanks to all for your replies.

machfive55, I see what you're saying but that gets me to having 6 relays (2 SSR + 4 mechanical). I guess I'd probably go for the 4 SSRs instead to minimize wiring and footprint inside the control panel. I'm interested in your current setup. I hadn't considered the 100% power boil. Are you doing 5 gallon batches and if so, do you have to switch the power on and off to keep it from boiling too rapidly? At 4000W, how much do you boil off in an hour? Also, what's the rough length of time to get to mash temp with the PID control and then time from mash temp to boiling?

bezel, I can't do it cause I don't have enough power to run all 4 elements at the same time. I could do this but only if one vessel was always powered off. I wish I had 240v.

jeffmeh, great explanation. To me, the first scenario you describe seems the safest and most foolproof.

You could use a 20a 3-position switch (or a lower rated switch with an SPDT contactor) to switch F1 between T1 - Off - B1. F1 would have to run to both T1 and B1 (each through an SSR). So you are at most powering 1 element with F1.

Similary, you would do the same with F2 to switch between T2 - Off - B2, so you are at most powering 1 element with F2.

Click to expand...

With your second scenario I could see myself at some point accidentally having both switches on. It's looking like I'll just be going with the 4 SSRs.



A couple general questions. You both seem to think it's ok to run 2000W element on a 20A circuit? Any concern that could be too much power? Also, what's a rough guess on how much it costs to get a 240V install? Just ballpark. Every single circuit I have right now is 120V. The breaker box says 100A 120/208V but I called comed and they say I have only 120V service.....

I haven't done any testing yet, I'm still building. I can switch either element in the BK on or off so I can boil with 2000 W or 4000 W. If 2000 W is still too much I plan on putting in a simple PWM circuit so I can dial down the current. I think 4 SSR's and a heat sink would take up a lot of space. Those mechanical relays are small, and the reason I went with them is because i wanted to go with the 22mm switches, which I can't find any that are bigger than 10A. You should be able to find other 20A switches then you won't need the relays and you can switch the loads directly.

If you don't run anything other than your elements you should be OK with 20A circuits. I would imagine you could run small loads like lights and PID's, but I wouldn't want to do much more than that. I am running a third circuit for my pump, PID's, vent and stir motor.

I can post pics of my setup tomorrow.

Regarding 2000w elements, at 120v that should draw 16 2/3 amps. Check the amperage on your pump. I would be surprised if it is more than 2 amps. In my view, you can go right up to 20 amps, as the 80% rule does not apply given that this is not a continuous load. Note that the pump motor can spike a bit when starting up. I don't think it will be a problem, but if it were tripping the circuit breaker, you could just turn the element off when starting the pump, then turn the element back on.

To add to my earlier post, I think you should come up with a design that:
1) Allows you to shut all elements off for safety using mechanical switches or relays (not relying on an SSR that can fail closed)
2) Makes it impossible to accidentally run more than one element at a time from each of your circuits

Keep us posted.

Here is the circuit layout of my panel. Notice that I did not update it to include the additional power supply for the accessories. The two different 20A busses are red and blue wires, with the neutrals for each in light red and light blue. The colored circles that are unlabled are indicator LED lamps. The current setup has 2 elements in the BK and 2 in the HLT (each are 2000W). I can run 2 at a time in any configuration.

The elements in the BK are not PID controlled, I figured I did not need temp control in the BK to maintain a boil. The elements in the HLT are PID controlled, each is on its own SSR.

The mash temperature is controlled by pumping hot water through a coil submerged in the mash, the water will be sourced from the BK, or the HLT. It's the reverse concept of an immersion chiller, using hot water instead of cold water. This operation will be controlled by a PID turning the pump on and off.

Also attached is the front panel layout.

I think a pid controlled pump seems like a bad idea. I can't find the duty cycle information, but isn't it like 1-8second cycles on an auberin pid? Seems like a lot of strain on the pump to be cycled like that.

Why use that second PID at all? Why not just turn the pump on, and set the temp of your water on the HLT PID? if you're mashing at 150, set it to 150 and let it recirc throughout the mash.

I know that without stirring, my immersion chiller only chills the 2-3 inches of water around it, and the rest of the water around doesn't change temp hardly at all. I would imagine this is the case in the mash too, but this seems like a much easier cleanup and setup then a HERMS system, so I'm very interested to hear how well it works. Good luck!

Edit: The picture is really hard to read because its so small, but what is the purpose of those two female plugs? The two male plugs are your power into the system right?

I like the simplicity of the SPST relays.

The auber PID I bought has an on/off mode for just this reason, the cycle rate can be adjusted 2-199 seconds. I think that is fine for this application. The idea is to just maintain a temp within a degree or two, I doubt the pump will need to run much in an insulated vessel. The other option you mention with controlling the water temp is a possibility as well, using two PID's at the same time. I will have to play with it a little to see what works. I saw this in a brewing magazine before, can't remember if it was zymurgy or byo. I will be using stiring as well.

Sorry about the small pic, for some reason the board likes to resize my pics. The two male are power in, the two female are accessory outlets for a vent and a stirrer motor. Both of these are wired on a third power supply. The elements have plugs as well, but they are not shown.

It seems to me that the most useful options are:

Both elements under PID control in HLT
Both elements full on in BK (wort heat up)
BK element under PWM control (boil), HLT element off
BK element under PWM control (boil), HLT element on (strike water heat up for 2nd batch)
Both elements full on in HLT (wash water heat up)
Both elements off.

I suppose it's just about possible that a very big batch might not boil with just 1 element on in the BK. But it would be a nuisance to have the PWM govern both elements in the BK, and then have to adjust the PWM control when splitting the power to turn on the HLT element for the second batch.

Likewise, I think it would be a bit of bother having either 1 or 2 elements under PID control. When switching from one to the other you would have to reprogram with different gain settings.

(As an aside, you might guess from this commentary that I find it hard to justify having a second element in the BK, because you only use it when bringing wort up to the boil. But that's not really the point I want to make.)

alien said:

It seems to me that the most useful options are:

Both elements under PID control in HLT
Both elements full on in BK (wort heat up)
BK element under PWM control (boil), HLT element off
BK element under PWM control (boil), HLT element on (strike water heat up for 2nd batch)
Both elements full on in HLT (wash water heat up)
Both elements off.

I suppose it's just about possible that a very big batch might not boil with just 1 element on in the BK. But it would be a nuisance to have the PWM govern both elements in the BK, and then have to adjust the PWM control when splitting the power to turn on the HLT element for the second batch.

Likewise, I think it would be a bit of bother having either 1 or 2 elements under PID control. When switching from one to the other you would have to reprogram with different gain settings.

(As an aside, you might guess from this commentary that I find it hard to justify having a second element in the BK, because you only use it when bringing wort up to the boil. But that's not really the point I want to make.)

Click to expand...

I would try to autotune the PID using only one element. Use both elements to bring the temp up to within ten degrees of the target, then turn off one element and set the temp for target. Something like that should work, and if you always use just the one element for reaching and maintaining final temp, hitting mashout, etc. then the PID will not "get confused."

I would also see if one element could maintain a good boil in the BK, and understand what manual % to set on the PID (or PWM if one were to go that way). Use both elements to get to just under boiling, then switch to one. So when using manual the setting is always based upon one element.

jeffmeh said:

I would try to autotune the PID using only one element. Use both elements to bring the temp up to within ten degrees of the target, then turn off one element and set the temp for target. Something like that should work, and if you always use just the one element for reaching and maintaining final temp, hitting mashout, etc. then the PID will not "get confused."

I would also see if one element could maintain a good boil in the BK, and understand what manual % to set on the PID (or PWM if one were to go that way). Use both elements to get to just under boiling, then switch to one. So when using manual the setting is always based upon one element.

Click to expand...

Thanks for that input. I haven't gotten as far as tuning the PID yet, but this info will help.

Sorry to hijack the thread.

Machfive55, happy to help. Out of curiosity, are you using the mini SPDT relays you linked to as SPST relays, by not wiring anything to the NO load terminal? http://www.auberins.com/index.php?main_page=product_info&cPath=2_31&products_id=250

I also find the diagram too small to really see what is going on.

Yes, I use those relays but I do not wire to the NC terminal.

Link to larger circuit diagram

jeffmeh said:

I would try to autotune the PID using only one element. Use both elements to bring the temp up to within ten degrees of the target, then turn off one element and set the temp for target. Something like that should work, and if you always use just the one element for reaching and maintaining final temp, hitting mashout, etc. then the PID will not "get confused."

I would also see if one element could maintain a good boil in the BK, and understand what manual % to set on the PID (or PWM if one were to go that way). Use both elements to get to just under boiling, then switch to one. So when using manual the setting is always based upon one element.

Click to expand...

That does sound like a pretty good strategy.

I suppose if you are doing step mashes you might want to try having both elements under PID control to speed up the ramps.

machfive55 said:

The auber PID I bought has an on/off mode for just this reason, the cycle rate can be adjusted 2-199 seconds. I think that is fine for this application. The idea is to just maintain a temp within a degree or two, I doubt the pump will need to run much in an insulated vessel. The other option you mention with controlling the water temp is a possibility as well, using two PID's at the same time. I will have to play with it a little to see what works. I saw this in a brewing magazine before, can't remember if it was zymurgy or byo. I will be using stiring as well.

Sorry about the small pic, for some reason the board likes to resize my pics. The two male are power in, the two female are accessory outlets for a vent and a stirrer motor. Both of these are wired on a third power supply. The elements have plugs as well, but they are not shown.

Click to expand...

Oh yea, if you can stretch out the duty cycle that long that'd be pretty neat! Why don't people do this with HERMS? Seems like it would be preferable because you could then set your HLT PID to your sparge temp, and actually have that water ready to go when the mash is done.

alien said:

That does sound like a pretty good strategy.

I suppose if you are doing step mashes you might want to try having both elements under PID control to speed up the ramps.

Click to expand...

Theoretically, if it were a large enough step you could try running both elements to get close then cutting back to one.

On the other hand, you could autotune with both 1 element and with 2, write down both sets of parameters, and manually set them depending upon what you were doing. I would probably always use the same element in single element mode, just in case there are any variations betweeen the 2.

Sounds doable. When you are mashing you are probably not going to be switching the BK on and off anyway.

jeffmeh, I agree with this 100%. Will do.

To add to my earlier post, I think you should come up with a design that:
1) Allows you to shut all elements off for safety using mechanical switches or relays (not relying on an SSR that can fail closed)
2) Makes it impossible to accidentally run more than one element at a time from each of your circuits

Click to expand...

machfive, my plan is really very similar to yours. I'm going to get the BK wired up first in the next couple weeks, then slowly add everything else for the HLT. Right now I just do 2-3 gal batches on the stove but its too messy. I'll have a 7.75g slim quarter HLT, a 15.5 keg BK, and probably about a 12g HDPE mash tun. I need all 3 to nest for storage. I like the PID pump idea, never thought of that one. Please let us know how it works once you've got it going. I am still deciding between pumping mash through the tube in the HLT or pumping hot water through the tube in the MT. I am leaning toward the first option because A) I assumed it would be really hard to control temp and B) I figured I was going to pump the wort at some point to re-circulate anyway so I could take advantage of that for heating as well. I do really like the idea of pumping water through the tube for cleaning reasons. Plus, I'm a little concerned that if my mash runoff is too slow I may not be able to maintain temp pumping wort through the HLT tube.

My plan is 1. heat mash water in BK and heat HLT to mash step temp (probably on a timer of some sort so it's ready to go when I want it). 2. Pump from BK into MT 3. circulate MT to HLT tube. 4. Drain from MT into BK. 5. Pump HLT to MT for sparge / pre-cleaning HERMS coil. 6. Boil, Chill, etc...

What are you using to make the wiring diagram picture? That looks incredibly useful.

I use spaceclaim to do the wiring diagrams. It is not the best option, its just what I have available.

Might Consider Using ie; Crydom Dual SSR's,
Can be controlled seperate or together, currently Posted topic w/3-PH SSR's
http://www.crydom.com/en/Products/Catalog/AdvancedWebPage.aspx?CategoryText1=Panel%20Mount&CategoryText2=AC%20Output%20SSR&CategoryText3=Dual%20Series%20independently%20controlled%20dual%20output%20solid-state%20relay;%20Ratings%20from%2025A%20to%2040A%20@%2024-530%20VAC&SBCatPage=

PLC-Guy said:

Might Consider Using ie; Crydom Dual SSR's,
Can be controlled seperate or together, currently Posted topic w/3-PH SSR's
http://www.crydom.com/en/Products/Catalog/AdvancedWebPage.aspx?CategoryText1=Panel%20Mount&CategoryText2=AC%20Output%20SSR&CategoryText3=Dual%20Series%20independently%20controlled%20dual%20output%20solid-state%20relay;%20Ratings%20from%2025A%20to%2040A%20@%2024-530%20VAC&SBCatPage=

Click to expand...

Those could definitely save some space.

That's a great idea with the dual out SSRs. I already have several MGR-1 D4825 SSRs so I will make use of those.

How does this first draft wiring diagram look? I'm going with 4 SSRs but otherwise trying to keep it as simple as possible. I don't really need any lights, timers, buzzers, etc... I do want it to be safe, so if I'm missing something please let me know.

Again to summarize the objective, it's two 120V, 20A lines input and 4 2kW elements, 2 in BK and 2 in HLT, where only 2 can be on at any given time.

As stated earlier, SSRs can fail closed (on). Your 3-position switches should not be wired to the "coil" of the SSRs, but should be wired either before the line or after the load. This way you will know an element is off when you switch it off.

Are you planning on using something like this for the switches? http://www.fruitridgetools.com/stor...SFItemDetail.aspx?sfid=136763&i=234642343&c=0

OK, here's my fix.



I think I have to switch after the load or else I won't be able to have one element in each vessel powered on.

For the switch, I was actually planning on using something like this:

http://shop.pkys.com/Blue-Sea-Systems-9093-AC-Selector-Switch-120120240V-63A-OFF2_p_339.html

........until I saw the price tag. Not gonna happen.

Yes, you need to switch after the load for what you are doing. And I think you can use those Auber mini spdt contactors without anything wired to the NO terminal, if you want to save some space, with a basic 3-position rotary switch.

The auber mini contactors are great. They even come with terminals, although the terminals aren't the best. So far they seem to be working well although I haven't put them under the load yet. That test is coming soon.

I have a few other suggestions, If I may.

After your hot lines enter the panel, use a switch and a 2 pole contactor, running both hot lines through the contactor. This would be your main power switch, and when off, the only parts of your panel that have hot lines to them are the switch and the line terminals of the contactor.

If you want, you can wire a 120v LED indicator light in parallel with each element. This would show you when each element is actually receiving power.

Have fun.