2 Position Switch To Control Voltage

[halejer03]

I built my first electric brewery several years ago. I recently moved, and decided it was time to clean the system up, do some rewiring, and replace some old parts. I am upgrading the elements from 4000W to 5500W. Even with the 4000W burners, during the beginning of the boil it would get a little furious and if not closely watched, boil over. So, naturally, I am worried about the 5500W being even more aggressive. This leads to the inevitable question of controlling the heat coming out of the element.

Long story short, I was trying to come up with a relatively cheap, easy solution and I think I have one, but can't find any information. I have 240 running to the elements currently, so 2 hot wires. I am thinking of running one hot directly to the element and wiring both a neutral and the second hot through a 2 position switch to the other terminal. This would regulate 120V vs 240V as a sort of high/low setting. It seems too simple to not be able to find anyone else who has done it.

Am I just not thinking of why this won't work? Thanks for all you help in advance.

 

[Cevan]

Why dont you just use the pid in manual mode to control the boil... you can set it to about 85% or so. No need to rewire anything.

Do you have a control panel? or do you just plug power right in ?

 

[halejer03]

Thanks for the reply!

I have a control panel using two Ranco temp controllers. I'd rather not spend the money on two new PIDS if I can avoid it. I found a switch for $11, vs two new PIDS at $30 each.

Do you know how the PIDS control the output? Do they use PWM or does it change the actual voltage/power output? Thanks!

 

[passedpawn]

I built my first electric brewery several years ago. I recently moved, and decided it was time to clean the system up, do some rewiring, and replace some old parts. I am upgrading the elements from 4000W to 5500W. Even with the 4000W burners, during the beginning of the boil it would get a little furious and if not closely watched, boil over. So, naturally, I am worried about the 5500W being even more aggressive. This leads to the inevitable question of controlling the heat coming out of the element.

Long story short, I was trying to come up with a relatively cheap, easy solution and I think I have one, but can't find any information. I have 240 running to the elements currently, so 2 hot wires. I am thinking of running one hot directly to the element and wiring both a neutral and the second hot through a 2 position switch to the other terminal. This would regulate 120V vs 240V as a sort of high/low setting. It seems too simple to not be able to find anyone else who has done it.

Am I just not thinking of why this won't work? Thanks for all you help in advance.

That would work fine. Note that you would only get 1/4 the heating power from the 120V.

The reason you don't see much of that here is because it's a lot easier to control the 5500W element with pulse width modulation. SO, for example, if you wanted only 25% of the power, the PWM would only turn the element 25% of the time.

Check this. Note that it does NOT require a PID. $22.
http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=332

 

[passedpawn]

Do you know how the PIDS control the output? Do they use PWM or does it change the actual voltage/power output? Thanks!

Yes, PWM. Very slow frequency PWM (i.e, 0.5 Hz or slower)

 

[DaleHair]

A PID needs a SSR also. What you want is a SPDT switch, wire the common to the element, N to one screw and the other hot to the other.

 

[Cevan]

The PID will change duty cycle of the SSR output... basically full on is 100% element on all the time, Manaul mopde at 85% will fire the element roughly every 5 seconds or so.
Make sure the switches you got are properly rated ... a 5500w element at 240 pulls around 22amps. In my experience they usually cost way more than 11$

Hate to hear you had a meltdown !!

 

[halejer03]

Thanks for all the comments.

A spdt is what I was thinking of when I said a two postition switch. Knowing the right terminology helps a lot. I am going to try this route first and see if once its boiling 1350W will keep it boiling.

Second option will be creating my own on off cycling. I have an arduino laying around, so if I need to setup PWM through my SSRs, I will go that route (with a slow cycle rate).

I have never seen an SSR that is controlled by voltage, I like the idea of that as well.

I'll let you know how it turns out this weekend!

 

[halejer03]

Yeah, I just did a quick ebay search for 30 amp 2 position switch, and what I was looking at is rated to 30 amps, but only at 12v dc. Its only rated to 10 amps at 240VAC. Looks like the hunt continues tonight, otherwise the arduino will be coming out of hiding.

 

[Cevan]

Just curious... how much you trying to boil 5 or 10 gallons

 

[halejer03]

10 gallon batches, so generally 11.5-12 gallons for 90 minute boil.

 

[BadNewsBrewery]

So here's my concern - with your load as the common leg and a single throw between neutral and hot, there's a possibility (slight? who knows) that the switch hasn't fully broken from one leg before engaging the other, which could create a short. Maybe it's not an issue, but getting a 3 position switch - ON-OFF-ON would ensure that you've broken the contact with one leg before engaging contact with the other, eliminating any chance of a direct hot-neutral short.

Maybe it's not an issue at all, but it looks like you're searching out low-cost switches and I'm never too confident on their build quality. That, and I'm a fan of over-engineering things like safety.

-Kevin

 

[DaleHair]

A SPDT switch is what is used as a three way switch for lighting. Home Depot will have them but they may only be rated for 15a, or you can try an electrical supply.

 

[alien]

IMO that's pretty good advice from BNB. And you probably want the OFF switch anyway.

The low voltage setting might not give enough power. Maybe try it out to see if that setting will keep a pot of water on a rolling boil.