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Old 05-07-2011, 11:33 PM   #1
thelorax121
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Default Switch for running element at 120v OR 240V?

So I am thinking of putting a rims tube together with a 240V 5000W HD element, and running it at the full voltage to heat up my strike and sparge water on its way from the filter to the HLT, then switching it to 120V and effectively making it a LD element when running wort through it as a RIMS. So my query is, what is the best way to wire a switch for this?

I have separate 120V and 240V inlets on my control panel, and I was thinking of either a 2-way switch with one NO contact and one NC contact with, one with a hot line from the 240V bus and another with a neutral line from its respective bus, then running each of them to the outlet for the element (my 240V service and therefore receptacles are 3 line by the way, hence the additional 120V inlet). Does this sound like it would work? Would it be wiser to use a 3 position switch like the one on Kal's build for selecting elements to ensure a clean break in the connection before switching the lines? Or is this a stupid idea to begin with, and if so is there a safer/easier/more effective way to accomplish this that I am overlooking? Thanks in advance for the input, it always helps to have a few minds working out a problem...

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Old 05-08-2011, 12:01 AM   #2
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DPDT relay and two ssr's

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Old 05-08-2011, 03:19 AM   #3
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Hmmm...that's one of those easy problems that need complicated solutions. Initially, what Djsethall said would be the easiest way (short of a big SPDT switch). However, if you follow that path, you must make absolutely sure you use good quality SSR's, that are designed specifically to fail open.
Now, in order to be 100% honest here, up until not long ago, I wasn't even aware there were SSr's that could fail closed, but it seems there are. Sorry I can't tell you what industry rating they must follow (I don't know the ratings you use here. Probably another member can help with that), but basically you need SSR's rated for explosive environments. Otherwise, if you switch and one of the SSR's stays closed, you're gonna have some fireworks...

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Old 05-08-2011, 03:39 AM   #4
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Hmmmmm, fireworks? If you have the 2 legs of your 220 circuit going to the first set of posts and make sure that you match 1 leg (say the black wire) to the other side for your 110 and your neutral to the other posts with the black wire and have the ssr's wired off the output of the relay, you will be completely safe. Even if the ssr fails closed, the worst that will happen is that you run at 220. Let me draw a pic to post. If you use this schematic, nothing can fail catastrophically. Even if the relay fails either n.c. or n.o., you wont have any probs. I speak for the trees

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Old 05-08-2011, 04:26 AM   #5
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Thanks for the input djsethall, the schematic helps quite a bit. I am however getting a bit tired, and think I need to give it a fresh look in the AM to fully digest it. Thanks again!

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Old 05-08-2011, 04:35 AM   #6
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Just make sure all the parts (relay and ssr) are rated for the load. I use a figure of double the anticipated load for safety

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Old 05-08-2011, 04:39 AM   #7
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Quote:
Originally Posted by djsethall View Post
Hmmmmm, fireworks? If you have the 2 legs of your 220 circuit going to the first set of posts and make sure that you match 1 leg (say the black wire) to the other side for your 110 and your neutral to the other posts with the black wire and have the ssr's wired off the output of the relay, you will be completely safe. Even if the ssr fails closed, the worst that will happen is that you run at 220. Let me draw a pic to post. If you use this schematic, nothing can fail catastrophically. Even if the relay fails either n.c. or n.o., you wont have any probs. I speak for the trees
Now I see what you mean. When you said a "relay" in your first post, instead of a contactor, I automatically thought you were using this kind of setup:



In this case, if one of the SSR's failed closed, you'd be in trouble.
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Old 05-08-2011, 04:55 AM   #8
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I can see where the confusion lies. I am planning a similar system for both my HLT and for my rims tube. 2 seperate systems, each controlled by PID. The 220 for the RIMS tube would be for getting water hot fast for cleaning etc. I have a second PID and six ssr's, just waiting to get everything welded up for the HLT and the second MLT (for high grav beers or larger batches, prolly both), just have to bide my time to slide it under the radar of SWMBO. You can see pics of my current setup in my gallery. It's a thing of beauty. I scored a commercial sink for a dishwasher pit and had 3 holes cut into it. 1 HLT and 2 MLT's in parralel. Again, just waiting to fund it.

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Old 05-08-2011, 05:07 AM   #9
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Quote:
Originally Posted by djsethall View Post
You can see pics of my current setup in my gallery. It's a thing of beauty. I scored a commercial sink for a dishwasher pit and had 3 holes cut into it. 1 HLT and 2 MLT's in parralel. Again, just waiting to fund it.
Just saw it. Yes, it is.
I love the fact that you won't have to climb on a ladder to feed the system. I guess you will use the pump to rack to the fermenter?
Just one thing though: are you planning to polish those poor kegs?
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Old 05-10-2011, 02:43 PM   #10
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Could I use the 822 switch below instead of a contactor to simplify things and save a bit of space on the internals? The estimated draw of my element at 220v would be about 22A which is still 2 amps below the 80% rule



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