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...

DPDT relay and two ssr's

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...

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

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!

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

djsethall said:

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

Click to expand...

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.

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.

djsethall said:

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.

Click to expand...

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?

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

Well, if you read my prior posts, you know I don't particularly like the "80% rule" (I use 70.7%), but yes, if you follow that rule, you can use it.
In both cases (contactor or switch) you will need to make sure the SSR's are deactivated when you do the switching, to minimize contact damage due to sparks. Other than that, either one should work just fine.

+1
I like the idea of having the power to the ssr's off during switchout

Yep.
I used to not care about that sort of thing, until one day, when I was working in industrial electronics, I saw the chief engineer almost lose a hand, while testing a selector switch. That gave me a whole new respect for open air contacts, and sparks.

Based on my calculations, I would be right at 73% with the 30A switch at 220V, so I should be good there.

When you say the SSR's need to be deactivated, do you mean that I need to have that on-off-on arrangement where all contacts are open, or do you mean that the signal from the PID should be turned off (eg. set to maual control at 0% power)?

I mean the heating element should be turned off (no current on the element circuit), so there are no sparks on the switch's contacts when switching voltages.

You don't need a ON-OFF-ON switch, but it would be a nice thing to have, if you can get it.