PID/SSR with SSVR power control

Has anyone ever wired a heater circuit using a PID to control an SSR (on/off) and then through a SSVR (potentiometer power control) to regulate peak power? What I am thinking of is using one circuit for RIMS and BK by just moving the power cord to the heaters and flipping a switch.

In the RIMS mode I want elevated power to heat strike water quickly but then reduced power, via SSVR power control, to maintain temp while mashing. Let's face it, very little energy is needed while mashing. The PID loop will fire the SSR circuit but with power limited by the SSVR and potentiometer.

In boiling mode the SSR would be on and power regulated with the potentiometer to control boiling action.

My concern is how the SSVR may react to cycling on and off?

If you want to use one control setup for both elements, you will be best off using one PID and one SSR to do both.

A PID can do precise control of the RIMS but will operate the SSR/element at full output when heating strikewater or raising the BK to boil temperature.

Using both a PID, SSR and SSVR needlessly complicates the control circuit and most likely will not work the way you want it to.

When selecting a PID, be sure to get one that has a manual mode of operation.

Thanks processhead. I agree, the circuit will get more complicated.

However, I would like to regulate peak power when the PID energizes the SSR during mash circulation. The main, and likely unconventional, reason is that I plan to install the heater directly in the MT under a false bottom. Since flow velocities will be considerably lower than in a RIMS tube, I'll need to reduce power density on the element surface to the 1kw range to keep element surface temperatures in the 180F range. See image of CFD model.

Additionally, I would like power regulation on the BK heater to control boiling aggressiveness.

That's why I think combining the two may be the way to go? The circuit will have a few added connections & switches but will the SSVR survive the on/off cycling from the SSR under PID control?

Yes, there are lot of threads discussing this option. I'm not sure who's actually done it though, but I expect that there are a few. It's really not a big complication - the SSVR is just a single device in series with the SSR, plus it's control circuit.

I can't see any problem with doing it. The cycle times on a PID are in the seconds range, and the SSVR should be fine with a changing current through it on those timescales (since the element is purely resistive, there won't be any significant inrush current or similar when the PID/SSR switches, so that's not an issue).

Another option would be to use a 4500W 220V element and switch it down to 110V for the mash, reducing the power down to just over 1000W.

dyqik said:

Yes, there are lot of threads discussing this option. I'm not sure who's actually done it though, but I expect that there are a few. It's really not a big complication - the SSVR is just a single device in series with the SSR, plus it's control circuit.

I can't see any problem with doing it. The cycle times on a PID are in the seconds range, and the SSVR should be fine with a changing current through it on those timescales (since the element is purely resistive, there won't be any significant inrush current or similar when the PID/SSR switches, so that's not an issue).

Another option would be to use a 4500W 220V element and switch it down to 110V for the mash, reducing the power down to just over 1000W.

Click to expand...

Thanks Dygik. My CFD study did show that I would be safe at 1kw so that could be a great option as well. I'll sniff around for those other threads relating to this matter. Thank you.

You can easily use only one SSVR with PID if last one has a relay output.

I like your idea, and had similar thoughts, but some issues you run into are that the pid is tuned to a specific amount of heat, which may be more difficult to replicate each time with a potentiometer. It would probably not work as well for any amount of electricity other than what the pid was tuned for. Maybe this is a non issue, I'm not sure.

The operating a 240v element at 110 method above is the way I went. I use a contactor to select whether one of the legs is a hot or neutral... Then I can heat strike water at 240 at 100%, then flip to 120 and use the pid while recirculating the mash.

Still to your point though, I only have to run the 6000w/240v element at 15% to maintain mash temps at 240, or about 60% at 120v...so there is definitely room to operate the element at a lower watt density to lessen any risk of scorching, which can be done with your ssvr idea. We can figure this voltage out though so we run the element at 100% to have the lowest watt density to maintain temp (of water at least, wort is similar, but different).

Have you seen this? Digital solid state power regulator You may be interested.

http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=444

The most flexible option is to run a PID with regular SSR, then another SSR controlled by the power regulator linked above. The line for the element would run through both SSRs in series. While the PID is trying to cycle, say for half a second at a time, the power regulator is chopping it at the millisecond increment level which is as close to power regulation as you can get. For one thing, you won't need to make decisions between which is doing the controlling. They both are.

Thanks to everyone that helped answer my questions. Merry Christmas!

Wacki said:

I like your idea, and had similar thoughts, but some issues you run into are that the pid is tuned to a specific amount of heat, which may be more difficult to replicate each time with a potentiometer. It would probably not work as well for any amount of electricity other than what the pid was tuned for. Maybe this is a non issue, I'm not sure.

Click to expand...

There's quite a bit of wiggle room in the actual power output of the element in a mash recirculation set up with an autotuned PID, so just a sharpie mark on the potentiometer would probably do. If you really wanted to control it, a power meter or ammeter would let you tune the output more precisely. In any case, there's another variable that affects the tuning parameters required - the recirculation flow rate, which will vary with the pump control valve setting, the viscosity of the wort and thickness of the mash bed, and will change through the mash anyway. That's probably a bigger factor than the setting on the potentiometer.

At least, this is what I find with my RIMS tube system. The autotuned parameters find by my PID controller are conservative enough that no serious oscillations in the temperature occur, even with the small volume being heated in the RIMS tube. In a system with a larger volume in contact with the element, the autotuned parameters would likely turn out to be even more conservative. It only takes a few minutes to re-autotune the PID in any case.

dyqik said:

Yes, there are lot of threads discussing this option. I'm not sure who's actually done it though, but I expect that there are a few. It's really not a big complication - the SSVR is just a single device in series with the SSR, plus it's control circuit.

I can't see any problem with doing it. The cycle times on a PID are in the seconds range, and the SSVR should be fine with a changing current through it on those timescales (since the element is purely resistive, there won't be any significant inrush current or similar when the PID/SSR switches, so that's not an issue).

Another option would be to use a 4500W 220V element and switch it down to 110V for the mash, reducing the power down to just over 1000W.

Click to expand...

I thought about doing this also and my thoughts on wiring it up were the same...I even bought the ssrv but in the end I didnt need it so its going in another panel I'm building.

dyqik said:

There's quite a bit of wiggle room in the actual power output of the element in a mash recirculation set up with an autotuned PID, so just a sharpie mark on the potentiometer would probably do. In any case, there's another variable that affects the tuning parameters required - the recirculation flow rate, which will vary with the pump control valve setting, the viscosity of the wort and thickness of the mash bed, and will change through the mash anyway. That's probably a bigger factor than the setting on the potentiometer.

It only takes a few minutes to re-autotune the PID in any case.

Click to expand...

if one uses a mypin pid you just have to set the "i" setting to 1 and the pid makes its adjustments much quicker without any autotuning needed it works like a hysteresis control ... I find it much more consistent than constantly autotuning depending on batchsize and such.

rudylyon57 said:

Thanks processhead. I agree, the circuit will get more complicated.

However, I would like to regulate peak power when the PID energizes the SSR during mash circulation. The main, and likely unconventional, reason is that I plan to install the heater directly in the MT under a false bottom. Since flow velocities will be considerably lower than in a RIMS tube, I'll need to reduce power density on the element surface to the 1kw range to keep element surface temperatures in the 180F range. See image of CFD model.

Additionally, I would like power regulation on the BK heater to control boiling aggressiveness.

That's why I think combining the two may be the way to go? The circuit will have a few added connections & switches but will the SSVR survive the on/off cycling from the SSR under PID control?

Click to expand...

Since you are putting the element in the MT, and not using a tube, now I can see why you are concerned about too much heating capacity under low flow conditions.
I have always been a little uncomfortable with the idea of direct heating the mash with an electric element for that very reason.
An SSVR might do what you are wanting, although I would be inclined to look at switching to 120 volt operation for the element to achieve the same end result.

augiedoggy said:

if one uses a mypin pid you just have to set the "i" setting to 1 and the pid makes its adjustments much quicker without any autotuning needed it works like a hysteresis control ... I find it much more consistent than constantly autotuning depending on batchsize and such.

Click to expand...

Yeah, a full PID may well be overkill for controlling our kind of systems, although a small volume RIMS tube might need one. Commercial ones like the morebeer systems seem to get away with Ranco controllers for HERMS systems.

Herms can be controlled with an on/off units because of the huge thermal mass. While I'm satisfied with my 240v/120v switch on my controller it does limit the power options to 5500 or 1375. For a tube RIMS and 5 gallon batches, 1375 is fine for hold and slow ramps. Larger batches with faster ramps to mashout would need around 2000 to 3000 watts and the power controller product is excellent for that. In the case of a directly installed element in a BIAB rig, infinite power control is almost a necessity. While a PID on manual controls average power, you can get some surging at under 60%

How did you set this up in the end? Did you use Bobby_M's suggestion?

Cheers,
SB

SandbaggerOne said:

How did you set this up in the end? Did you use Bobby_M's suggestion?

Cheers,
SB

Click to expand...

I wound up doing the following with heaters mounted directly (via triclover) into MT, HLT and BK:

1) The control for the heater in the MT will be via PID but I added an extra relay to allow the element to run on 240V while heating water to strike and then switch to 25% power at 120V while mashing & circulating. Hopefully this will prevent any scorching issues.

2) The HLT heater will always be powered at 240V via PID.

3) The BK will always be powered by 240V but I am using a SSVR with a potentiometer for boil intensity control.

Cheers

in my setup I use a SSR and a VSSR with the outputs wired in parallel with the

And with the inputs selectable with a switch between a PID and a variable resistor.
NealM

nealm said:

And with the inputs selectable with a switch between a PID and a variable resistor.
NealM

Click to expand...

In case you didnt know there is an edit button. So you can edit and ad to your comments without double posting.

So if you have a PID and SSR and a VSSR, you would have a lot more control by wiring them in series and not using a switch to either PID or SSVR. I understand why you think you want that, in that you either want auto temp control OR boil intensity, but if you set the PID's SV to 220F it will always fire the element and then you use the dial for intensity. The benefit of the series wiring is that you also now have power control when the PID is acting like a PID (set point temp control).

rudylyon57 said:

I wound up doing the following with heaters mounted directly (via triclover) into MT, HLT and BK:

1) The control for the heater in the MT will be via PID but I added an extra relay to allow the element to run on 240V while heating water to strike and then switch to 25% power at 120V while mashing & circulating. Hopefully this will prevent any scorching issues.

2) The HLT heater will always be powered at 240V via PID.

3) The BK will always be powered by 240V but I am using a SSVR with a potentiometer for boil intensity control.

Cheers

Click to expand...

Seems like the simplest solution. On a related note, I've been thinking of ways to run two elements simultaneously off a single 240V 30A circuit. I have a two vessel system. BK also serves as HLT pre-boil. I was thinking of using a contactor to switch Brew kettle element between 240V/120V and running a RIMS element at 120V so that 120V in BK/HLT can maintain temp even while RIMS is running but can switch back to 240V for the boil. This should be possible as long as the 120V setup is wired so the BK and RIMS are using different hot legs, right? At 120V my BK element draws 11.4A and my RIMS element draws 12.5A.

Cheers,
SB

SandbaggerOne said:

Seems like the simplest solution. On a related note, I've been thinking of ways to run two elements simultaneously off a single 240V 30A circuit. I have a two vessel system. BK also serves as HLT pre-boil. I was thinking of using a contactor to switch Brew kettle element between 240V/120V and running a RIMS element at 120V so that 120V in BK/HLT can maintain temp even while RIMS is running but can switch back to 240V for the boil. This should be possible as long as the 120V setup is wired so the BK and RIMS are using different hot legs, right? At 120V my BK element draws 11.4A and my RIMS element draws 12.5A.

Cheers,
SB

Click to expand...

I run 4500w element and a 1000w 240V (cartridge heater in my rims) plus 2 24v dc pumps and my control panel off of my 30a line... my amp meter shows a max draw of 26amps with everything on 100% at once...
a1000w 240v element only draws 4- 4.5amps...

rudylyon57 said:

Thanks processhead. I agree, the circuit will get more complicated.

However, I would like to regulate peak power when the PID energizes the SSR during mash circulation. The main, and likely unconventional, reason is that I plan to install the heater directly in the MT under a false bottom. Since flow velocities will be considerably lower than in a RIMS tube, I'll need to reduce power density on the element surface to the 1kw range to keep element surface temperatures in the 180F range. See image of CFD model.

Additionally, I would like power regulation on the BK heater to control boiling aggressiveness.

That's why I think combining the two may be the way to go? The circuit will have a few added connections & switches but will the SSVR survive the on/off cycling from the SSR under PID control?

Click to expand...

On a configuration like this one illustrated in the picture # 3 from rudylyon57 which is the best place to put the temperature probe and how long it must be?

sgarrozzo said:

On a configuration like this one illustrated in the picture # 3 from rudylyon57 which is the best place to put the temperature probe and how long it must be?

Click to expand...

I would put the controlling temp probe as close to the element, but not in contact, as possible. During the mash, you don't want to let the wort heat up to the point where enzymes start to denature quickly. The farther the probe is from the element, the hotter the wort near the element can get before the controller lowers power to the element, and the more likely you are to over heat the wort locally. I would also install a second temp probe in the bulk of the mash, as it is likely to be cooler than wort near the element. With two probes you can set the control temp to slightly higher than the desired mash temp in order to actually get the bulk of the mash up to target temp.

Brew on

doug293cz said:

I would put the controlling temp probe as close to the element, but not in contact, as possible. During the mash, you don't want to let the wort heat up to the point where enzymes start to denature quickly. The farther the probe is from the element, the hotter the wort near the element can get before the controller lowers power to the element, and the more likely you are to over heat the wort locally. I would also install a second temp probe in the bulk of the mash, as it is likely to be cooler than wort near the element. With two probes you can set the control temp to slightly higher than the desired mash temp in order to actually get the bulk of the mash up to target temp.

Brew on

Click to expand...

This is a picture I get from the Colorado brewing system:

https://www.dropbox.com/s/rxm41ti9o... Colorado Brewing Systems-0.03.20.70.jpg?dl=0

[ame]https://www.youtube.com/watch?v=uROkO0gJLRQ[/ame]

http://cobrewingsystems.com/nano-brewer-home-electric-brew-system-20-gallon-kettle/

You can see the position of the heating element that isn't 90° from the inlet of the pump like in the picture posted by rudylyon57. Is it e better position? I don't know why.
When you speack about " the bulk of the mash" in this case where is it?
(Maybe I don't traslate well in italian)

doug293cz said:

I would put the controlling temp probe as close to the element, but not in contact, as possible. During the mash, you don't want to let the wort heat up to the point where enzymes start to denature quickly. The farther the probe is from the element, the hotter the wort near the element can get before the controller lowers power to the element, and the more likely you are to over heat the wort locally. I would also install a second temp probe in the bulk of the mash, as it is likely to be cooler than wort near the element. With two probes you can set the control temp to slightly higher than the desired mash temp in order to actually get the bulk of the mash up to target temp.

Brew on

Click to expand...

With my heater as shown in the CFD plot, I had my probe in the mash maybe 2" from MT wall and 2/3 high in the grain bed. My experience was that the temperature would swing too far (maybe +/- 3F as I recall). So, what doug293cz proposes is spot on. FYI-I wound up moving heater into a RIMS tube.

sgarrozzo said:

This is a picture I get from the Colorado brewing system:

...

You can see the position of the heating element that isn't 90° from the inlet of the pump like in the picture posted by rudylyon57. Is it e better position? I don't know why.
When you speack about " the bulk of the mash" in this case where is it?
(Maybe I don't traslate well in italian)

Click to expand...

Here's a picture that shows how things are positioned in the bottom of a Colorado Brewing Systems kettle (from this thread.)



The temp probe is the short, small diameter "needle" just left of top center. This isn't as close to the element as I would like to see the temp probe, but apparently it is good enough, or CO Brew Systems would have redesigned it to get better performance.

I'm not a flow expert, but I would think that having the outlet port at 90° to the element would provide a slightly more uniform flow field across the element. Maybe @rudylyon57 could weigh in on that.

By "bulk of the mash" I mean near the center of the grain bed up in the basket above the liquid only volume at the bottom of the kettle below the basket.

Brew on

rudylyon57 - doug293cz : Everything's clear now.



doug293cz great image!!



I want add a question now: If I add a rims tube I can go whit a 3000 Watt element at full power?

my element is a camco ULWD 14" lenght

3kW might be a bit overkill, but I'm fine with 2kW. Just make sure you have plenty of flow before turning it on. The closer you can get the temperature sensor to the element, the better.

If using a stock 18" RIMS tube, choose a temperature sensor probe long enough to get the sensor end right up to the element.

sgarrozzo said:

rudylyon57 - doug293cz : Everything's clear now.



doug293cz great image!!



I want add a question now: If I add a rims tube I can go whit a 3000 Watt element at full power?

my element is a camco ULWD 14" lenght

Click to expand...

3kw for heating water only at full flow is no problem. However, 3kw may be on the high side while mashing or stepping mash temps. It will all depend on how much flow you can pull through your mash without getting stuck.