Selector switch to use one pic for two seperate element/probes

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

StumpyJohnson

Member
Joined
Dec 7, 2009
Messages
22
Reaction score
0
Location
Grass Valley
Ok, so I'm looking to convert my brewery to electric and I will probably have a myriad of questions but here's the first.

I'd like to use one temp controller to operate two different elements. By having the elements and the probes on selector switches, can this be acheived?


Essentially, I'd like to use the single pid to control temp on the hlt during strike/mash. Then flick a few switches and use the same pid to control temp on the bk...

Possible?

Anyone done it and have opinions?

Anyone done it and have wiring diagrams?

Anyone done it and have a burning sensation?
 
The easiest way to do it would be to have 2 temp probes, and 2 elements. Just plug in the ones you want to use at any given time.

Otherwise, all you need is a 3-pole switch for the RTD (Or 2 for thermocouple) and I would double the SSRs for the elements, and switch the control wires form the PID to one element or the other, on the low voltage side. It's a hell of a lot easier than trying to find a 30 amp switch...

Basically, you set it up for 2 elements. Each one has 2 SSRs. So your mains connect parallel on the input side of the SSRs, and the outputs of the SSRs go to your elements. Then the trigger wires from the PID go to a 2-pole switch that selects which set of SSRs it triggers. If you can find a 5-pole switch (Or build one, it's easy to stack contact blocks on industrial switches) you can switch the RTD and the PID trigger with one switch.
 
So just build and wire the box for one unit and unplug the 220 plug and the plug from the probe eh? I was hoping for something a little more elegant...

But I guess it keeps the build price down.

I did see some posts about having two relays with heatsinks and switching there...but it did get a bit muddled...

I need to find a post with minimal minutia...
 
It's really about how far you want to go. With a 5-pole switch, you can do it with one switch. If you want the easiest to wire, it's unplug one, and plug in the other.
And there are about a dozen ways in between to make it work.
 
The only issue is putting a switch between two thermocouples and the PID renders them both useless. They use a precise metal composition to read temp and introducing the different materials in the switch will throw them off. I am assuming this will be for a HLT and BK? If so I would only have a probe in the HLT and just run the BK in manual mode, temp isnt that crucial unless you want to monitor chilling anyway.
 
The only issue is putting a switch between two thermocouples and the PID renders them both useless. They use a precise metal composition to read temp and introducing the different materials in the switch will throw them off. I am assuming this will be for a HLT and BK? If so I would only have a probe in the HLT and just run the BK in manual mode, temp isnt that crucial unless you want to monitor chilling anyway.

OK, this is progress...

So if I run two elements and two ssr's, from one pid swiched at the ssr's what sort of switch might I use...?

Because yes, I'm really only concerned with the hlt temp. but I would like to use the pid to operate the two elements. Some sort of 3 position switch would be awesome...

Edit: I'd heard that the voltage involved meant that switching at the 220 end was hard on the wiring and that swithing at the relays was the better choice. I'm not much of an electrician. Carpentry is my gig. But I can follow a schematic...
 
The only issue is putting a switch between two thermocouples and the PID renders them both useless. They use a precise metal composition to read temp and introducing the different materials in the switch will throw them off. I am assuming this will be for a HLT and BK? If so I would only have a probe in the HLT and just run the BK in manual mode, temp isnt that crucial unless you want to monitor chilling anyway.

Thermocouples, yes. But that can be compensated for with the temp offset in the PID, as the difference should be the same for both probes.

With RTD's it wouldn't be an issue.
 
Being very honest, you are going to need two RTD Probes and two SSR's so you may as well spring for $35 for a second PID. If you don't you will need a two section double pole, double throw switch. That's not going to be a cheap switch.
 
I agree with SawDustGuy. In the original post there was no mention of doing this as cheap as possible, or limited space. If it is in the budget and you have the real estate to mount another PID, I really think you'd be better adding another PID.
 
Being very honest, you are going to need two RTD Probes and two SSR's so you may as well spring for $35 for a second PID. If you don't you will need a two section double pole, double throw switch. That's not going to be a cheap switch.

I agree with SawDustGuy. In the original post there was no mention of doing this as cheap as possible, or limited space. If it is in the budget and you have the real estate to mount another PID, I really think you'd be better adding another PID.

I disagree to some extent. :D

If the BK is being controlled just to regulate the strength of the boil (PID is in "manual mode"), then you don't need a temp probe in it at all.

If your element kill switches are placed between the SSR and the element, then you can use a single SSR and just make sure the right element is enabled.

Like Ed said, there was no mention of trying to keep costs to a minimum, but if that is one of the goals, single SSR, single PID, and single temp probe can work here.
 
I disagree to some extent. :D

If the BK is being controlled just to regulate the strength of the boil (PID is in "manual mode"), then you don't need a temp probe in it at all.

If your element kill switches are placed between the SSR and the element, then you can use a single SSR and just make sure the right element is enabled.

Like Ed said, there was no mention of trying to keep costs to a minimum, but if that is one of the goals, single SSR, single PID, and single temp probe can work here.

Sure he can do that, but if he wants to switch elements using a switch, and he is using a large element, I am sure he will find out that the switch or contactor will not be cheap either.
 
HD has a 30a dpst switch which will handle switching a 5500w element. I dont remember what it runs but I want to say 10-15 bucks
 
Why not just switch the control side of the SSR? It makes a lot more sense (to me) to put a switch on the control side which would allow only one of the SSRs to receive a signal at a time. It also seems like this would be way cheaper, like a few $.
 
Why not just switch the control side of the SSR? It makes a lot more sense (to me) to put a switch on the control side which would allow only one of the SSRs to receive a signal at a time. It also seems like this would be way cheaper, like a few $.

That is what I did. See my build at the link above. There is a schematic there.
 
How about this:




(Click the image for a full scale printable diagram for 11" x17" paper)

One PID (and 1 temp probe in the HLT). As Walker stated there is no need for a second temp probe. The boil is controlled using manual mode.

The contactors are $14.50 each so they certainly will not break the bank.
 
Why not just switch the control side of the SSR? It makes a lot more sense (to me) to put a switch on the control side which would allow only one of the SSRs to receive a signal at a time. It also seems like this would be way cheaper, like a few $.

The only caveat is that an SSR can fail closed. Then you switch to the other SSR and both are hot. In practice, this condition would just blow the breaker but just sayin...

Another alternative is to just use a portable heatstick with integrated temp probe. Now it can be moved from vessel to vessel with no switching.
 
Sure he can do that, but if he wants to switch elements using a switch, and he is using a large element, I am sure he will find out that the switch or contactor will not be cheap either.

Two 120V coil duoble pole contactors, rated for 240V/40A, would be $26 total with shipping off ebay. Might be able to find them cheaper.

selector switch that can handle 120V/1A would be less than $10 I imagine.

Depending on how "kill" functionality gets implemented, one of the contactors might be necessary anyway.

It's a lot cheaper than a second PID + SSR + heatsink.

We can debate this stuff endlessly. Everyone of us has their own little twist on how to approach the designs. That's part of the reason I am trying to stay out of design threads.... the guy asking for advice gets pulled in a dozen different directions by the rest of us. :D

cheers, fellas.
:mug:
 

Yes, I like being able to monitor the chilling on the PID display, too. It's not necessary, but sure is nice. I have the temp probe mounted in the HERMS coil and I chill by pumping wort through that coil as it sits in an ice water bath. I manage to get away with a single probe in the system that shows temp during mash and then later temp during chill.
 
...
We can debate this stuff endlessly. Everyone of us has their own little twist on how to approach the designs. That's part of the reason I am trying to stay out of design threads.... the guy asking for advice gets pulled in a dozen different directions by the rest of us. :D

cheers, fellas.
:mug:

Walker you are 100% correct.

There are way to many possibilities and often way to few requirements provided. Sometimes the questions are so open for interpretation that you have to make some assumptions to offer any input. So everyone tends to jump in with their own vision of the end result. I think it says a lot to have so many willing to offer advice, opinions, and be willing to help.

Not sure how to improve the process until we get to the point where someone asking a question can know exactly what they want before asking, but then I guess that defeats the point of asking the question.

I hope folks don't start shying away from the design questions. I'm sure there are still plenty of ways to "skin a cat" that have yet to be discovered.

Now back to the topic:
How about a PID and a PWM compared to switching a single PID?
 
I gave a solution that exactly answers the OP's topic. He wants to use one PID to switch between 2 temp probes and 2 elements. It is exactly what I do today, and the schematic is in the link I gave.

Discussing whether 2 temp probes are necessary is a different topic. So is any discussion of PWM. Though I do enjoy those discussions, truly.
 
Back
Top