Rims Input Needed

[FarsideOfCrazy]

Hi Brewing Bob, What I'm most interested in is what are you going to use to control the temp?

You mentioned a digital temp controller, but is it going to be a variable controller or just an on/off type. Ive been doing a bit of reading about electrical setups and I've deciced that that is the way I want to go with my HB setup but haven't made my mind up on what is the best sort of controllers to use. I've seen SSR (solid state relays) on ebay and temp controllers but this is just a on off type controller. But I would have thought that some sort of potentiometer type unit might be better.

edit. I'm not just looking at a RIMS controller but elements/controllers for HLT and brew kettle.

 

[newguy]

Hi Brewing Bob, What I'm most interested in is what are you going to use to control the temp?

You mentioned a digital temp controller, but is it going to be a variable controller or just an on/off type. Ive been doing a bit of reading about electrical setups and I've deciced that that is the way I want to go with my HB setup but haven't made my mind up on what is the best sort of controllers to use. I've seen SSR (solid state relays) on ebay and temp controllers but this is just a on off type controller. But I would have thought that some sort of potentiometer type unit might be better.

edit. I'm not just looking at a RIMS controller but elements/controllers for HLT and brew kettle.

On/off control is the only possible type. A potentiometer arrangement would create a tremendous amount of waste heat in the control unit and that's why they're not used. That's why PWM (pulse width modulation) is employed (pulsing the element on/off). By turning the element full on or full off, the energy from the supply is almost 100% consumed by the heating element when on, not by the control circuitry. This means less waste heat in the control unit, which translates to a more efficient use of energy.

 

[Justin]

On/Off control works fine, personally I measure temp just before the return manifold on the output of the heating chamber/exchanger. If your flow is reasonable I have found that grain bed temp is right there with output temp, if the probe was elsewhere in the system then i doubt they would be that close. Actual use has shown them to end up very, very close in temp.

On the pump priming issue, so many people have trouble with it but it really can be very simple. My recommendation and the technique that i use is to design your plumbing so that you can fill your lines before grain ever hits the system, and that you can fill any line in your brewery at any time. I use my HLT as the source for filling the lines. Here is a plan of how my plumbing works (I'v used the simple picture, it now has a HERMS for fun but the procedure is the same).



This is how my brew goes. I heat my water in my HLT, once I'm at or near temp I open valve 1 and valve 4 (valve 2 and 3 are closed, so nothing flows). Then I open valve 2 wide open. This blows air out of the pumps inlet and starts to fill the mash tun through the bottom via gravity. Close valve 2. Open valve 3-gravity from the HLT now fills that hose. Now I turn the pump on and pump the hot strike water over to the mash tun from the HLT and run it at full tilt, this clears any remaining bubbles. Close valve 4 (and valve 2 if you want but it's not needed).

Once my mash tun has the required volume of strike water, if it needs a bit more heat I'll pump it though the heat exchanger until it gets to the required temp or I'll use a hand held element, either way I just let the pump run. Then I close valve 3 and mash in (pump can still run, valve 2 can still be open, nothing will flow). Once I'm mashed in and finished stirring I will give it a minute to settle and then slowly start to crack open valve 3. Valve three is where I regulate the pump flow speed.

Notice how I can control the speed with valve 3 standing upright, looking into the tun while watching the actual outflow speed rather than bending down and adjusting a valve directly on the pump - blind to what is actually coming out of the pump (this is something to consider). Having the valve controlling speed at the bottom of the system directly on the pump is a little clumsy in my books. I can watch the outflow and change the pump speed and keep adjusting it until I'm happy with the flow.

I also dont have to disconnect any input lines throughout the brew so I dont lose prime. If for some reason I do loose prime I can just fill the hoses from the HLT again. Simply close the valve on the vessel, disconnect the hose from the vessel, open HLT valve and let the water fill the lines again, close HLT valve then reconnect the hose and you are ready to go again. Pain free. Trying to clear air from the pump lines using wort from the mash tun just doesn't work because the flow isn't there and you are being careful not to compact the bed, use the HLT and you can crack it wide open. Just make sure you disconnect the end of the hose so there isn't an airlock preventing flow. This is where most people come unstuck i think.

In this picture when I transfer to the kettle I'll close valve 2 and move the hose going to valve 3 over to the kettle. Then I'll control pump speed transferring to the kettle using the kettle valve.

Hope it gives you a few ideas. As always, I'm happy to answer question if you need it. Good luck and hope it works out.

More pics here:
http://hbd.org/discus/messages/366/33903.html?1187742085

 

[matho]

hi guy's

i found this website yesterday it could be usefull has alot of cool stuff
link

cheer's matho

 

[rwmingis]

Hi Brewing Bob, What I'm most interested in is what are you going to use to control the temp?

You mentioned a digital temp controller, but is it going to be a variable controller or just an on/off type. Ive been doing a bit of reading about electrical setups and I've deciced that that is the way I want to go with my HB setup but haven't made my mind up on what is the best sort of controllers to use. I've seen SSR (solid state relays) on ebay and temp controllers but this is just a on off type controller. But I would have thought that some sort of potentiometer type unit might be better.

edit. I'm not just looking at a RIMS controller but elements/controllers for HLT and brew kettle.

Hi Farside of Crazy,

Newguy is right, a potentiometer used to control power to the element would be huge, waste lots of energy, and generally get really hot. I know of two ways of controlling the power to the heating elements in an efficient manner.

Option 1: Manual control using an SSR (Solid state relay).

This is the option that I imagine you are looking for, and it's VERY easy. This uses a solid state relay that is controlled by a potentiometer. The relay does the power control (it basically does the work done in option 2, but all in the background), all the potentiometer does is tell the relay how much power to let through, so no power is really lost through the potentiometer. Note, this potentiometer in many cases is live, so you'd need to make sure that it's protected from water and fingers. Also, make sure you address the heat issue, many SSR's require a heat sink, depending on how much power you are supplying. I know of some however that are rated for 40 amps. If you are using only 5 amps (1200W) then you "may" not need a heat sink. A bit of trial and error will tell. See "SSR-125 Solid State Relay" at http://www.oceancontrols.com.au/relays/ssr/conch_ssr.htm

Option 2: Automatic digital control of an SSR

This is the method I am using. Basically, you use a Zero crossing SSR, it doesn't turn on or off until the AC sine wave crosses the 0V level which reduces EMF noise. See SSR-100 Solid State Relay SS-240DA 40A @240VAC at http://www.oceancontrols.com.au/relays/ssr/conch_ssr.htm. Then using a microcontroller, you send it a PWM signal that has a duty cycle between 0 and 100% in 1% increments at a PWM frequency of 1 second. To explain a little better, AC mains works at 50 Hz. Knowing this and knowing that an AC sine wave has a positive and negative half that look exactly the same, you really have a pulsing wave at 100 Hz (if you don't care about positive or negative). If you use your microcontroller to turn the SSR on for 0.25 seconds and off for 0.75 seconds during each 1.0 second period, you have a duty cycle of 25%, and effectively you are running the element at 25% power. (ie it's on for 25 cycles and off for 75 cycles) It's very easy this way, if you know how to use a microcontroller. If you're patient, i'll happily share my code with you when I make mine.

Thanks to "leathalCorpse" to explaining option 2 to me in the first place

Cheers

Rob

 

[FarsideOfCrazy]

Thanks for that Bob. Yeah it makes sense that a potentiometer would use too much power, just like a dimmer does for lights.

So how would one of these relays go hooked up to one of these?

http://karlslittlegarden.com/TEMPERATURE.html

or

http://cgi.ebay.com.au/PID-TEMPERATURE-CON...1QQcmdZViewItem

Or have I got it wrong and you can't use something like this :huh: ?

 

[newguy]

Either of those controllers would work. In fact, that type of controller is what a lot of brewers use for their RIMS/HERMS. Should you ever want to add a pump and "upgrade", you'll already have a controller that will handle it.

 

[rwmingis]

Either of those controllers would work. In fact, that type of controller is what a lot of brewers use for their RIMS/HERMS. Should you ever want to add a pump and "upgrade", you'll already have a controller that will handle it.

Hi FSOC,

These are designed to run the SSR's (exclusively I think). The one you were looking at gives 8V at 40ma, which is well within the control voltage range for a 4-32V SSR. However, I don't know if these modules have PWM output on a 1 second period scale as I discussed in my previous post. You'd have to investigate.

Cheers,

Rob

 

[LethalCorpse]

Wouldn't matter what the control period is. They're PID controllers, so they're designed for PWM. There will be an issue if they're set up for 60Hz at low resolution though - a zero crossing SSR on 50Hz power would give spurious results.

 

[ausdb]

The first one, is only a relay output ie binary on/off
http://karlslittlegarden.com/TEMPERATURE.html
If you want proportional output you will need one with SSR output

 

[LethalCorpse]

Nah, it's got to be an SSR output. I know it says relay output, but they mean solid state relay - they have to, if it's got PID control. You can't do PID control with a mechanical relay, and they claim PID control.

 

[ausdb]

I have seen those controllers available as both SSR output and just plain relay output. I would not assume anything unless I had it in writing or an actual spec sheet on the device

 

[Yorg]

I have about 4 PID controllers, of both varieties, SSR and regular (internal) relay.
Check out Auber Instruments in the US, where I got mine from.
I would use the SSR variety for controlling an element - which I do on my steam generator - works fine.
The relay variety may not drive 10A @ 240V, limiting your element wattage, and in any case would have a short life from all the on and off.

 

[Thirsty Boy]

Nah, it's got to be an SSR output. I know it says relay output, but they mean solid state relay - they have to, if it's got PID control. You can't do PID control with a mechanical relay, and they claim PID control.

ahhh, sorry. Yes you can and I do.

My Rims runs from a PID unit's very much mechanical "relay" outputs via a 12V control circuit routed through a separate 10A mechanical relay.

The reason for the mechanical relay instead of an SSR... well I understand Mech relays and I dont understand SSRs, it was under $10 from dick smith and I didn't have to worry about heat sinks etc.

Yeah sure - it'll wear out eventually, and when it does I will swap to the SSR circuit of the PID unit - till then I am happily obtaining PID control from my mechanical relay set-up.

TB

 

[LethalCorpse]

fair enough, I'll buy that, I just don't understand how. Is it just using a very long control period? The reason I was so sure in that last post that you can't do it with mech relays is not just the stress on the relay, but the timing issues of it taking a few ms to switch a relay. I guess if you're only switching on and off once every few seconds it makes sense.


BTW, if you understand mech relays you understand SSRs. As far as the user is concerned they're exactly the same thing. You just need to make sure it's got the right specs for the load, same as a mech relay. You usually won't need a heatsink, unless the load is close to the rating and you expect to be running close to 100%

 

[rwmingis]

fair enough, I'll buy that, I just don't understand how. Is it just using a very long control period? The reason I was so sure in that last post that you can't do it with mech relays is not just the stress on the relay, but the timing issues of it taking a few ms to switch a relay. I guess if you're only switching on and off once every few seconds it makes sense.


BTW, if you understand mech relays you understand SSRs. As far as the user is concerned they're exactly the same thing. You just need to make sure it's got the right specs for the load, same as a mech relay. You usually won't need a heatsink, unless the load is close to the rating and you expect to be running close to 100%

I'm with you LC, but there is one safety difference with SSR's and that is that the circuit beyond the SSR is still hot even when it's turned off. They always conduct a minute amount of current even when off on the order of microamps I think. However, most circuits have a load which would drain the output of the relay and keep it near 0V. If the circuit was open though, the output of the SSR would be 240V even when off!

 

[LethalCorpse]

Well, yeah, that's true, but ultimately it doesn't mean much. As you say, it only allows microamps when "off" - the impedance is so high that the open circuit voltage is 240VAC, but if you put yourself in the circuit you couldn't electrocute yourself. Maybe if you opened up your chest and put it directly on either side of your heart, but even then you need a few milliamps (the open heart surgery in the shed might do some damage though). Either way, the SSR is only to control the power output, you consider it to be live whenever the controller has power. If you want it to actually be off you use the main switch on the back. And if you actually want to open it up and touch the contacts you switch it off, unplug it from the wall, burn some incense, throw salt over your shoulder, check it again, check it a third time then think about it carefully for a bit.

 

[Thirsty Boy]

Long control period it is - I run the PID on a 2 second control period when I am mashing and a 10-15 second control period when I use it as a fermentation controller.

I have figured that at the rated number of actions for the relays lifetime and the frequency with which I brew, it will last for slightly longer than 10 years.

I am somewhat happier about the notion if using an SSR now though. Thanks for that.

TB

 

[LethalCorpse]

No problem. You'll probably find it performs a lot better when it's got a much shorter control period - the longer your control period gets, the more you approach the behaviour of an on-off controller. For the PID loop to work effectively it has to be able to give variable power to the element, and faster control periods more closely approximates this.

What's your controller TB? In most cases you should be able to just swap out your mechanical relay with an SSR, but if you give me a model I should be able to confirm. SSRs draw very little current, much less than a mechanical relay so it might need a little tweaking to make sure it can turn off correctly. Shouldn't be necessary though, and if it is it'll just be a resistor across the inputs or something. And if you get a 40A SSR you won't need a heatsink for a 10-15A element.

 

[FarsideOfCrazy]

Ok, so now I know about the same as I did before :huh: .

So lets do a hypothetical.

LC if you were looking go electric what would you buy ,(actual items), in the way of some sort of controller/controllers to run a 3600w element and on a different circuit a 2400w element. These element would be used for a brew kettle and HLT.

I was thinking that a 3600w element would be big enough to do a double batch with the assistance of a hand held 2400w element if needed.

I'm lucky that I already have a 15a circuit in the garage for running my floor sanding machines so running bigger than 2400w elements is a prob unless I want to go to 4800w.

The other thing I'm looking at is just buying a 40 litre urn for $280 to be used as a HLT.