Can you "dim" an electric element with a Variac?

[Funkenjaeger]

Curious, why is a variac so much larger and more expensive than this speed control? Arent they working on the same principle?

No, a variac is a variable transformer, which changes the voltage of the AC waveform but leaves it more or less a clean sine wave - one that can handle high power is going to be a huge iron core and a whole lot of copper wire; lamp dimmers and router speed controls are solid-state devices that switch the AC waveform on and off, modifying its shape to vary the effective power. Variacs have their applications - sometimes you need a clean sine wave - but for a heating element it doesn't matter.

 

[willynilly]

So, that still begs the question, will a $20 Harbor freight router speed control, control a 2000W heating element without melting down?

Id like to see someone try it, but I also dont want to see someone get hurt, or start a fire.

 

[wyzazz]

So, that still begs the question, will a $20 Harbor freight router speed control, control a 2000W heating element without melting down?

Id like to see someone try it, but I also dont want to see someone get hurt, or start a fire.

Sounds like a job for the MythBusters! Or you could sacrifice a heatstick and a Harbor Freight router controller to the cause.

 

[Fletch]

Since the HF says the speed control is good for "15 amps and under", and a 120 volt 2kw element is about 18 amps, I really don't think we need the Mythbusters for this one.

 

[willynilly]

I think the point we are driving at here is, will a cheap Harbor Freight type speed control handle an element that falls within the amperage range.

Obviously we know that an 18A draw on an element will exceed the 15A speed control, bad example. You can get 20A speed controls, so will a 2000W element work on a 20A speed control... there, that is better.

Is this speed control like a dimmer then? 2000W dimmers are quite pricey, that makes me wonder if a speed control will work, there may be more than something to it than a simple amp rating needed

We are way off the OP topic, but since this was brought up, it would be nice if someone knew, for sure, what the deal is. Maybe BrewBeemer would know, he is extremely intelligent when it comes to all things electrical.

 

[Sawdustguy]

Is this speed control like a dimmer then? 2000W dimmers are quite pricey, that makes me wonder if a speed control will work, there may be more than something to it than a simple amp rating needed.

Nope, that is, all that is to it. An element is a simple resistive device. If you really think about it, a light bulb is a simple resistive device also. A dimmer of sufficient size or a speed controller would work rather well. The router speed controller and dimmers are both pwm devices.

 

[willynilly]

Cool , for $30 you can control a 2000W element

 

[Sawdustguy]

Cool , for $30 you can control a 2000W element

If it can handle the current. You can vary the voltage to the element but I don't know how stable the temperature would be. It could vary +/- 5 degrees, who knows. You won't know unless you try. It's more suitable for controlling the boil than providing a precise temperature for strike and mash water or maintaining the mash temperature. It's not like a control system where there is a temperature probe being read by the PID and adjustments being made by turning the element on and off.

 

[willynilly]

Right, I think this whole thread is about the boil. Not temp. control

Though it was never really stated

 

[Fletch]

Another thing to keep in mind about the idea of running a 2000 watt element on a router speed control. Most household 120 circuits are 15 amp, not 20. The breaker might hold for a while running a 2k element, but it's not a smart thing to do.

 

[kezgin]

i still say try a stove control. i've got one that i pulled off a stove to try this with, it's rated for 2350 watts at 240v. haven't gotten around to hooking it up yet, but i don't see why it wouldn't work

 

[willynilly]

It will, there is a guy here actually using a crazy electric setup made from stove top electric elements.

The problem is that 2000W or 2500W is really too weak to boil with alone. Which then means you would need at least (2) elements, and (2) controls etc.

 

[kezgin]

It will, there is a guy here actually using a crazy electric setup made from stove top electric elements.

The problem is that 2000W or 2500W is really too weak to boil with alone. Which then means you would need at least (2) elements, and (2) controls etc.

does he have them submerged in the wort?

 

[willynilly]

does he have them submerged in the wort?

No, he is using actual stove top heating elements arranged under the kettle, using like three of those infinite switches

 

[TheAleMaster]

No, he is using actual stove top heating elements arranged under the kettle, using like three of those infinite switches

It is BargainFittings that has the set up you are referring to. Here is the thread:

https://www.homebrewtalk.com/f51/alternative-electric-solution-144016/

 

[wyzazz]

i still say try a stove control. i've got one that i pulled off a stove to try this with, it's rated for 2350 watts at 240v. haven't gotten around to hooking it up yet, but i don't see why it wouldn't work

It WILL work, and well if you can grab another one and install a second element/build a second heatstick. For 5gal batches it just isn't enough to boil alone, and for precise temperature control a PID/SSR is just a better solution.

Just my $.02. Brew on!

 

[kezgin]

It WILL work, and well if you can grab another one and install a second element/build a second heatstick. For 5gal batches it just isn't enough to boil alone, and for precise temperature control a PID/SSR is just a better solution.

Just my $.02. Brew on!

yeah i figured 2k watts wouldn't be enough, especially not for 10 gals like i usually brew. when i do have the cash to go all electric, i'm probably just going to use ssr's with a brewtroller setup

 

[weirdboy]

Right, I think this whole thread is about the boil. Not temp. control

Though it was never really stated

Why would you even bother with any dimmer or other control if you're only interested in the max load anyway?

 

[willynilly]

Why would you even bother with any dimmer or other control if you're only interested in the max load anyway?

What? Max load? You mean max output? Because people typically dont boil at max output.

I am not interested in this at all, I have a control solution.

 

[wilserbrewer]

The problem is that 2000W or 2500W is really too weak to boil with alone. Which then means you would need at least (2) elements, and (2) controls etc.

willy,

I figure one element running full at 2000w, with a second 2000w element controlled w/ the one 20 amp controller below. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130370376427

2000 - 4000 watts available to boil. I'll report back w/ results. Seems as if this may be a very simple way to regulate a boil up to 10 to 12 gallons. I am currently using two elements at 2000w resulting in vigorous boil at 4000 and a low boil at 2000.

 

[willynilly]

willy,

I figure one element running full at 2000w, with a second 2000w element controlled w/ the one 20 amp controller below. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130370376427

2000 - 4000 watts available to boil. I'll report back w/ results. Seems as if this may be a very simple way to boil up to say 10 gallons. I am currently using two at 2000w resulting in vigorous boil at 4000 and a low boil at 2000.

Yes, yes, I should have realized this... one would run at 100%, the other would be adjustable. Youd need at least a 40A circuit, or run on (2) 20A circuits

 

[lustreking]

Since the HF says the speed control is good for "15 amps and under", and a 120 volt 2kw element is about 18 amps, I really don't think we need the Mythbusters for this one.

I use one of those speed controls to throttle back one of my 1500 watt heat sticks. It seems to work well.

 

[Jknapp]

To report back on this.. I ended up testing a boil whilst using 2 x 2kw elements. One running 100% and the other controlled by a 2kw variac.

To be totaly honest, I didn't see the variac as being much of a value add. I used the variac to 'dim' the boil down a bit and sure it worked fine, however, it just didn't make that MUCH difference to the funtionality of my brewery.

I scrapped the variac concept and now run my 2 x 2000w elementails 100% wide open & use a fan to control boil overs. I don't see the variac as being necessary. Gucci factor was high, but due to the cost and lack of availability to most people.. FAIL.