STC-1000 wiring in parallel difficulties

[thecebruery]

Hoping the electricians/DIYers here on homebrewtalk can help me out, 'cause I'm having a tough time wrapping my brain around this one!

Background: I have two 3 barrel fermenters with glycol jackets. The glycol jackets have solenoid valves on them. My glycol reservoir (which is a cooler with a submersed air conditioner evaporator coil) has a single pump in it on the glycol loop. I've mounted three STC-1000s on this glycol chiller unit - one temperature control unit is for the evaporator coil which chills the glycol mixture, and the other two are for the pump and the individual solenoid valves on their respective fermenters.

Here's my issue. I would prefer it if the pump was not running constantly (it's rated for continual use, but I have an additional circulation pump, so it's not needed for that, and why strain it/waste the electricity if I don't need to?), so I would like for the two STC-1000s that monitor the temperatures in Fermenter A and Fermenter B to activate the pump if either of them goes above the setpoint (and the STC switches to "cool" mode). However, since I only have one pump, I only want the one ball valve associated with the particular fermenter that's in "cool" mode to be opened - the other should remain shut (unless, of course, both are in "cool" mode). In other words, I want:

Fermenter A "off" & Fermenter B "off" - pump off, fermenter A valve closed, fermenter B valve closed

Fermenter A "on" & Fermenter B "on" - pump on, fermenter A valve open, fermenter B valve open

Fermenter A "on" & Fermenter B "off" - pump on, fermenter A valve open, fermenter B valve closed

Fermenter A "off" & Fermenter B "on" - pump on, fermenter A valve closed, fermenter B valve open


I obviously have something wired incorrectly, or maybe there's no way to to do it without a relay or something more complicated, because right now, if either STC is in "cool" mode, both of my solenoid valves are activated (as well as the pump). I don't know how to sever whatever needs to be severed in order to make the pump the only thing that turns on if "either" of the STC switches close and the solenoid valves be linked only to their respective STCs.

Is it possible to rig these units to produce an effect like this? I know practically nothing about electronics - everything I've wired up before has been far simpler than this and I've been able to follow wiring diagrams and directions online with great success, but this is really throwing me for a loop. Can anyone suggest a course of action or a resource that might be able to help?

Help me Homebrewtalk.com - you're my only hope!

 

[ajdelange]

There are lots of ways to do this. Perhaps the easiest would be to use valves that have auxiliary contacts that reflect the valve position. These are commonly used in hydronic heating systems. The valves are connected to individual thermostats for the individual zones. When a zone wants heat it sends a low voltage signal to its valve which is held open by the signal. When fully open the auxiliary contact closes. The auxiliary contacts are all in parallel so that any valve opening signals the circulation pump (and heat source) to start running. These are readily available in the US but I'm guessing there isn't big demand for multi zone heating systems in the Phillipines and multizone AC seems to be managed by individual split pack systems in that part of the world.

Another approach using what I expect you have would be to connect a diode to each of the valve inputs in the same polarity i.e. anode to each valve and then tie the two cathodes together. A couple of resistors in series from the common point to the low side of the power supply (ground) then form a voltage divider to drop the voltage to less than 20 volts and a capacitor between the junction of the resistors and the low side of the power supply (ground) smooths the ripple from the fact that the diodes only conduct on one half cycle. The result is 20 VDC relative to the low side of the power supply (ground). That could be used to trigger an SSR which runs the pump.

There are other ways to do it too with the general principle being that you must have a logical OR with the output isolated from the inputs.

 

[thecebruery]

This is exactly what I was looking for! A diode sounds like it would do the trick. Do they sell what you're describing as a complete package? That is, the diode, plus the rectification portion, plus the capacitor to smooth out the noise? I'm a little fearful of sourcing the individual components and dropping a "1" somewhere in my calculations, and it would be nice if it came preassembled.

If not (and knowing that my pump pulls only 115 watts and the STC-1000s and the solenoids will pull something like 3 watts, if any of that even matters, as well as that the PH runs on 220V two-leg), what ratings am I looking for?

Yikes, it's been so long since Physics II!

 

[ajdelange]

This is exactly what I was looking for! A diode sounds like it would do the trick. Do they sell what you're describing as a complete package?

I doubt it very much.

If not (and knowing that my pump pulls only 115 watts and the STC-1000s and the solenoids will pull something like 3 watts, if any of that even matters, as well as that the PH runs on 220V two-leg), what ratings am I looking for?

I take that last to mean that the pump and valves are connected between 220V and a neutral. In that case if we want to allow 20 ma to flow in the voltage divider and want 10 V for the SSR gate the resistor with the capacitor across it would be 500Ω (.02*500 = 10). The ripple is at 100 Hz (I assume the Phillipines uses 50 Hz distribution). Assuming that having the impedance of the parallel capacitor (across the 500Ω resistor) less than 10% (50 &#937 would suppress the ripple sufficiently we'd need a cap of 32 ufd or more. The other resistor has to drop 220 - 10 = 210V at 20 ma so it would have to be 10.5 k. Note that this resistor will be dissipating 4.2 watts so you will have to make it up of 10 100K resistors is parallel or 10 1K resistors in series, each capable of dissipating over a half watt unless you can find a single 10.5 k resistor with over 5 watts rating.

The diodes will have to be capable of 20 ma and, of course, have PIV ratings greater than 350 V

Another approach which might actually be simpler but based on the same idea would be to obtain two wall warts each capable of producing enough DC to trigger an SSR (5 - 20 V). Wire the input of each between the valve hots and neutral. Connect the two negative wires from the wall warts together and join that with the (-) terminal on the SSR. Connect each wall wart + output through a diode to the (+) terminal. The diodes (you probably don't even need them) can then be low voltage diodes, you don't have to buy any capacitors or resistors nor worry about dissipation capabilities of resistors.

 

[thecebruery]

My understanding of the electricity here is that each of the two legs is 110V - there is no neutral. That is, one leg is at -110V, the other at +110V. Does that change anything?

 

[ajdelange]

One of the big advantages of the wall wart scheme is that it doesn't matter. Whatever the first valve actuator is connected to, one wall wart goes there and the other goes to whatever the second valve actuator is connected to. All you need to know is what voltage is applied across the valve actuators and buy wall warts for that voltage. I am assuming it is 220V and it doesn't matter whether that 220V is 220 V WRT a neutral or Ground or floating (no ground or neutral).

 

[thecebruery]

Great, I should be able to get my hands on two of those no problem. Is there an alternative to the SSR? I likely would have to order one of those online and I'm not sure how long it would take to get here. I imagine even an electromechanical relay would be hard to find here, though maybe I'll get lucky.

So again, just to wrap my brain around it, the wall warts are essentially just being tied inline between the valve actuator leg and the point where the current legs are joined to tie in to the SSR/relay/whatever actuates the pump (and I can't just tie the pump in directly, because the voltage has been stepped down?), and the guts of the wall wart only allow the current to flow one way, creating the logic "OR" gate that we need.

EDIT: Belay that! Apparently, I can get my hands on SSRs locally. Woohoo. Thanks again so much for your help ... got my hands on two old Nokia chargers (100-240V in, 5.0V/350mA out) which I'll be cutting open later.

 

[ajdelange]

Great, I should be able to get my hands on two of those no problem. Is there an alternative to the SSR? I likely would have to order one of those online and I'm not sure how long it would take to get here. I imagine even an electromechanical relay would be hard to find here, though maybe I'll get lucky.

You will need some sort of relay that can be operated by the wall wart output voltage. An SSR relay would certainly work and these should be easy to find though a mechanical relay with a DC coil would work just as well.

So again, just to wrap my brain around it, the wall warts are essentially just being tied inline between the valve actuator leg and the point where the current legs are joined to tie in to the SSR/relay/whatever actuates the pump...

I think you have it but just to be sure let's assume that you have a blue wire and a red wire with 220V between them. Connect:
1) STC-1000 1 pin 1 to blue
2) STC-1000 1 pin 2 to red
3) STC-1000 1 pin 7 to blue
4) STC-1000 1 pin 8 to Valve 1
5) STC-1000 1 pin 8 to Wall Wart 1 AC in
6) Other terminal on Valve 1 to red
7) Other AC input terminal on Wall Wart 1 to red
8) (+) output of Wall Wart 1 to the anode of a diode -->|-- (side away from the bar on the diode body.
9) Cathode side of diode (side near the bar) to SSR (+) or relay coil
10) (-) output of Wall Wart 1 to SSR (-) or other side of relay coil

11) to 20) Repeat Steps 1) - 10) for STC-1000 2, Valve 2 and Wall Wart 2
21) Connect SSR line terminal or one side of relay NO contact to blue
22) Connect SSR load terminal or other side of relay NO contact to pump.
23) Connect other wire from pump to red.

(and I can't just tie the pump in directly, because the voltage has been stepped down?),

That's correct

...and the guts of the wall wart only allow the current to flow one way, creating the logic "OR" gate that we need.

The wall warts themselves should be such that you can wire the outputs together and have one energized with no detrimental effect on the other but the diodes insure this. The diodes form the OR circuit and the wall warts provide the necessary isolation between the valves.

EDIT: Belay that! Apparently, I can get my hands on SSRs locally. Woohoo. Thanks again so much for your help ... got my hands on two old Nokia chargers (100-240V in, 5.0V/350mA out) which I'll be cutting open later.

I'd be surprised if you couldn't.

 

[thecebruery]

Just wanted to thank you again - got everything wired up, and it works like a charm. I used two Nokia phone chargers (4.8V and 5.0V) without the external diodes (figuring I could add them later if the transformers didn't isolate the two circuits), but they did! The SSR I got my hands on seems to have failed closed, unfortunately, but the LED cycles on and off when the cooling cycles on the STC activate, so I presume simply swapping that out will turn the pump off when both STCs are off.

Thanks again for your help - cheers!

 

[ajdelange]

Yep, that's how they fail. Delighted to hear the idea works otherwise.

 

[augiedoggy]

subbed (I want to do the same type of build myself soon)

 

[thecebruery]

Yep, that's how they fail. Delighted to hear the idea works otherwise.

So I've got everything hooked up and ready to go - it works perfectly, except ...

The fermenters I just unloaded don't have the electronic ball valves I was told they'd have! So I have to source a few locally, or wait months for them to come from China (no thanks). 240V components are pricey ... if I get a valve that's rated, say, 6V DC (same as the transformers I'm using now), will I need to put another two transformers in-line (say, upcurrent from where the two I have now are) to power this? Or is there a way to use the two I already have now that are functioning as current check valves and powering my single SSR? My paranoid and half-baked understanding of the circuity suggests to me that I will ... so I need to determine if the costs associated with doing that outweigh the added costs of a 240V solenoid.

Or am I way off, and somehow the diodes (or perhaps more logically the wonders of DC current?) and whatnot are able to work their magic in a way that will forbid the DC current to flow backwards and activate both ball valves because the signals are both hooked up to the same SSR?

Would love your thoughts Thanks!!

 

[ajdelange]

With low voltage DC valves you would need 1 DC power supply. Wire the + side to each of the controllers and the - side to the - side of the valve actuators. Wire the other side of the NO contact pair on each of the controllers to the + terminal on one of the valves. Wire the anode of diode to each of the valves' + terminal. Join the diode cathode (banded end) leads together and connect to the SSR + terminal. Wire the SSR - terminal to the power supply -

 

[jorgemog]

This thread is awesome. I have used STC-1000s before and am expecting some coils for my fermenters. The SSR setup seems easy enough for me to try in a big control box.

Thanks again for this info!

 

[augiedoggy]

Hoping the electricians/DIYers here on homebrewtalk can help me out, 'cause I'm having a tough time wrapping my brain around this one!

Background: I have two 3 barrel fermenters with glycol jackets. The glycol jackets have solenoid valves on them. My glycol reservoir (which is a cooler with a submersed air conditioner evaporator coil) has a single pump in it on the glycol loop. I've mounted three STC-1000s on this glycol chiller unit - one temperature control unit is for the evaporator coil which chills the glycol mixture, and the other two are for the pump and the individual solenoid valves on their respective fermenters.

Here's my issue. I would prefer it if the pump was not running constantly (it's rated for continual use, but I have an additional circulation pump, so it's not needed for that, and why strain it/waste the electricity if I don't need to?), so I would like for the two STC-1000s that monitor the temperatures in Fermenter A and Fermenter B to activate the pump if either of them goes above the setpoint (and the STC switches to "cool" mode). However, since I only have one pump, I only want the one ball valve associated with the particular fermenter that's in "cool" mode to be opened - the other should remain shut (unless, of course, both are in "cool" mode). In other words, I want:

Fermenter A "off" & Fermenter B "off" - pump off, fermenter A valve closed, fermenter B valve closed

Fermenter A "on" & Fermenter B "on" - pump on, fermenter A valve open, fermenter B valve open

Fermenter A "on" & Fermenter B "off" - pump on, fermenter A valve open, fermenter B valve closed

Fermenter A "off" & Fermenter B "on" - pump on, fermenter A valve closed, fermenter B valve open


I obviously have something wired incorrectly, or maybe there's no way to to do it without a relay or something more complicated, because right now, if either STC is in "cool" mode, both of my solenoid valves are activated (as well as the pump). I don't know how to sever whatever needs to be severed in order to make the pump the only thing that turns on if "either" of the STC switches close and the solenoid valves be linked only to their respective STCs.

Is it possible to rig these units to produce an effect like this? I know practically nothing about electronics - everything I've wired up before has been far simpler than this and I've been able to follow wiring diagrams and directions online with great success, but this is really throwing me for a loop. Can anyone suggest a course of action or a resource that might be able to help?

Help me Homebrewtalk.com - you're my only hope!

I am building almost the same thing (waiting on my $2 solenoid valves to arrive). I plan on having 4 stc 1000+ units controlling 4 dual pole relays with one pole used to switch the valve and the other used to turn my glycol chiller pump on and off... since the poles are activated at the same time but have no contact with each other theres no issues with voltage going where it shouldnt. plus to complicate things my valves are 24v dc as well as the coils on my relays... my chiller is 240v so one pole on the relay will have 120v through one side of the relay.

My heater strips are also 24v dc so it all works out.

 

[dyqik]

I'm not intending to derail the discussion here too much, but at some point it gets easier and cheaper to implement your control system on a RaspberryPi/Arduino reading all the temperatures via 1 wire temperature sensors and driving relays appropriately, with the logic implemented in software rather than building a complex hardware system out of several STC-1000s and relays. About 3-4 STC-1000s plus some SSRs and wall warts would be my personal break-even point for trying to do it in hardware vs software.

I think some of the software can be found off the shelf - e.g. see the discussion at http://forum.brewpi.com/discussion/377/glycol-friendly and http://ask.brewpi.com/question/472/is-brewpifermtroller-ready-for-glycol-jacketed-cooling-yet/

 

[jorgemog]

... I plan on having 4 stc 1000+ units controlling 4 dual pole relays with one pole used to switch the valve and the other used to turn my glycol chiller pump on and off...

I think that is the easiest way to go. Do you have any link for a place to find those relays?

I'm not intending to derail the discussion here too much, but at some point it gets easier and cheaper to implement your control system on a RaspberryPi/Arduino reading all the temperatures via 1 wire temperature sensors and driving relays appropriately, with the logic implemented in software rather than building a complex hardware system out of several STC-1000s and relays. About 3-4 STC-1000s plus some SSRs and wall warts would be my personal break-even point for trying to do it in hardware vs software.

I think some of the software can be found off the shelf - e.g. see the discussion at http://forum.brewpi.com/discussion/377/glycol-friendly and http://ask.brewpi.com/question/472/is-brewpifermtroller-ready-for-glycol-jacketed-cooling-yet/

I know. I've read all about brewpi and actually their new iteration looks awesome, but I only need one STC1000 and I know nothing aboyt Rpi, Arduinos or programming.

 

[augiedoggy]

I think that is the easiest way to go. Do you have any link for a place to find those relays?




I know. I've read all about brewpi and actually their new iteration looks awesome, but I only need one STC1000 and I know nothing aboyt Rpi, Arduinos or programming.

I just searched for relay on ebay... I wanted relays with a 24v coil so I searched "24v relay 4 pcs" (I wanted 4).... I got omron ones with the mounting bases that have screw terminals for $21 with the shipping from Michigan.
I would look at the stc 1000+ thread... they are really a huge improvement over a regular stc 1000+ because they do multistage programmed temp profiles and ramping... put they display in F...

I bought 4 regular unprogrammed A400_p version stcs and bought a ardiuno clone for $7 and learned to program them myself here. https://github.com/matsstaff/stc1000p .. its actually easy.
I bought one from black box and the rest here from this seller.

http://www.ebay.com/itm/NEW-Pro-All...398?pt=LH_DefaultDomain_0&hash=item3cec2e0fa6

 

[jorgemog]

Excellent. One last question. I've seen the STC-1000+ fix, but I live in Mexico and we use Celcius. Is there a way to switch between those once the STC has been flashed?

 

[augiedoggy]

Excellent. One last question. I've seen the STC-1000+ fix, but I live in Mexico and we use Celcius. Is there a way to switch between those once the STC has been flashed?

Good news!
There is a Celsius version of the stc 1000+ software since the member here who wrote the code is in europe... (Sweden I believe) if you order them preflashed from the two guys selling them here just specify you want Celcius... https://www.homebrewtalk.com/f258/stc-1000-a-464348/ they also come in 220v or 12v or 110v flavors...

there are two sites to get them preflashed...
http://www.boostbysmith.com/diy.html

http://www.blackboxbrew.com/

 

[alphaomega]

Excellent. One last question. I've seen the STC-1000+ fix, but I live in Mexico and we use Celcius. Is there a way to switch between those once the STC has been flashed?

You can flash either F or C version.

 

[thecebruery]

Glad to see some other people doing this. The unit I built is up and running and operating well - it's currently holding one fermenter full of a 1.043 blonde w/ US-05 at 68F and another with a hoppy 1.064 robust porter w/ S-04 at 63F.

The styrofoam cooler keeps out heat surprisingly well - I lose maybe a degree or two over the course of the entire period where the pump is off/the solenoids are closed. Naturally, when the solenoids open and the pump kicks on, the glycol bath temperature rapidly increases, as warm glycol from the jackets is pumped back in to the reservoir.

A little thermal grease in the thermowells has gotten the lag down to 0.5C or so - that is, I overshoot my temperature by about 0.5C if everything turns on - so I've adjusted my setpoints and temperature range to match (+/- 0.5C).

I also installed a power failure alarm in it - a 220V relay closed if the unit loses power, completing the circuit between a 9V battery, a keyswitch (so I can disarm the alarm if I intentionally turn the unit off), and a 100 dB buzzer. I can hear it from inside my house, so it serves its purpose.

I stabilized my glycol w/ about 2% w/w borax, as the only propylene glycol I could find locally was medical grade (~$60 for a 20 liter carboy, which--when combined with 10 gallons of distilled water--gave me a 33% 27F solution, filled both jackets and all the hoses, and submerged the air conditioning coil completely, leaving me maybe 20% clearance in the cooler, perfect fit).

Make sure you put y-strainers inline before your solenoids - I had a piece of styrofoam get sucked up in to my lines and overcooled one of my fermenters a few days back. Lesson learned.

I'll probably be redesigning the control panel (which is really just a painted piece of wood occupying the place where the vent on the front of the aircon unit used to be) soon to include a 4th STC to control the temperature of a 500L insulated cold liquor tank I'll be keeping on the roof outside.

It's not pretty, but it gets the job done and I'm happy to provide pictures if anyone wants them.

 

[augiedoggy]

Glad to see some other people doing this. The unit I built is up and running and operating well - it's currently holding one fermenter full of a 1.043 blonde w/ US-05 at 68F and another with a hoppy 1.064 robust porter w/ S-04 at 63F.

The styrofoam cooler keeps out heat surprisingly well - I lose maybe a degree or two over the course of the entire period where the pump is off/the solenoids are closed. Naturally, when the solenoids open and the pump kicks on, the glycol bath temperature rapidly increases, as warm glycol from the jackets is pumped back in to the reservoir.

A little thermal grease in the thermowells has gotten the lag down to 0.5C or so - that is, I overshoot my temperature by about 0.5C if everything turns on - so I've adjusted my setpoints and temperature range to match (+/- 0.5C).

I also installed a power failure alarm in it - a 220V relay closed if the unit loses power, completing the circuit between a 9V battery, a keyswitch (so I can disarm the alarm if I intentionally turn the unit off), and a 100 dB buzzer. I can hear it from inside my house, so it serves its purpose.

I stabilized my glycol w/ about 2% w/w borax, as the only propylene glycol I could find locally was medical grade (~$60 for a 20 liter carboy, which--when combined with 10 gallons of distilled water--gave me a 33% 27F solution, filled both jackets and all the hoses, and submerged the air conditioning coil completely, leaving me maybe 20% clearance in the cooler, perfect fit).

Make sure you put y-strainers inline before your solenoids - I had a piece of styrofoam get sucked up in to my lines and overcooled one of my fermenters a few days back. Lesson learned.

I'll probably be redesigning the control panel (which is really just a painted piece of wood occupying the place where the vent on the front of the aircon unit used to be) soon to include a 4th STC to control the temperature of a 500L insulated cold liquor tank I'll be keeping on the roof outside.

It's not pretty, but it gets the job done and I'm happy to provide pictures if anyone wants them.

There is another older thread in the DIY section where someone is controlling 5 or so plastic homemade conical with a very similar setup.

 

[jorgemog]

There is another older thread in the DIY section where someone is controlling 5 or so plastic homemade conical with a very similar setup.

I saw that thread a while ago and was too lazy to go through 80+ pages. Yesterday I realized that within the first 3 or so I learned a lot on how to build the pipes for glycol and return. Thanks!