Electric Element Questions

[leiothrix]

I'm looking to buy an element for my 50L pot-cum-kettle and have a few questions about it.

I only plan on doing single batches (i.e. ~23L in the fermenter). I have a 15A circuit available nearby which helps.

The elements I'm looking at are either 3000W or 3600W.

Based on my experience with a Crown Urn I'm guessing that I need a little bit more than 2400W.

More obviously makes thing heat quicker, but then I have to worry about power control.

I think that I would probably need power control on the 3000W anyway, so might as well get the 3600W. What do people use to control electric element power? I could build a burst fire controller if someone could point me in the direction of a decent circuit, or pre-built unit that doesn't cost an arm and a leg.

Also, what about coatings? Is plain copper ok, or Incoloy 800? To my mind Incoloy would be better due to better corrosion resistance, but will it leach nickel and kill me or something?

The element I'm specifically looking at is from Tobin's 3267AG736 3600W 1IN BSP Foldback Incoloy 800 345mm ($67.82). Curiously the 3000W is (almost) $20 more.

How should it be mounted? I have a 1" BSP hole (~32mm) in my pot already, but no socket. I'm not keen on welding the pot at all. Can I use a locknut on the inside, or do I need a skin/bulkhead fitting or something? One of the posts I found mentioned finding a SS tank socket first. That post was a few years old, is it still valid?

Thanks,
Rob.

 

[Yorg]

I had a custom job made by Romar.
Can't remember exactly what power, I think 3600, but it is on a 20 amp circuit. I suggest leaving a little head room so you don't trip the circuit when someone turns the telly on. (I just boiled 30 litres in mhy other pot which has a 2000W, and it didn't take that long to come to boil after mash out, so 3000W I think is enough.)
Copper won't last as long - only 2 or 3 lifetimes.
Both my pots have weldless fittings - nuts. However, I replaced the washers with home made ones cut from silicon baking mat - food safe. No leaks.
I agree, you do want power control - I don't know how the gas guys manage, since you can't really turn those burners down by much. (When I was using gas I used to have 30% evaporation rates, but I got to boiling quickly.)
I have a PID controller that can ne configured to turn the element on and off through an SSR to effectively get a % Pulse Width Modulation output.

Cheers.

 

[Thirsty Boy]

you could always install several lower power elements and switch them on and off.

My personal experience:

2400W brings to a boil slowly but boils perfectly well a single (23L fermenter) batch in a converted keg style boiler - but struggles to get an adequate rolling boil with teh same wort volume in a pot with a wider opening (60L robinox). You can solve this by reducign the effective surface area by using a partial lid, or as I do by floating something on the surface of the boil. This restricts your evap rate and increases the vigor of the boil. In both circumstances my pots were lightly insulated.

So - I suggest a possible option could be a single 2400W element for the main boil part - enhanced by a seperate 1200W element to help you get to the boil faster, then be switched off.

Power controlling a bigger element will of course work - just tossing out an option that wouldn't need the electronic jiggery pokery.

I also use and recommend over the side immersion elements rather than fixed elements. Easier to clean and you can use them anywhere for anything when they aren't fixed into your pot.

TB

 

[silvana]

I asked a similar question not so long ago as I wanted to do some small 10L boils and my 2400W immersion heater boils off 32% or so.

bear09 pointed me in to this (which I haven't bought or used yet no affililation......) but I sopke to the guy in Sydney and he said its exactly what I need. You have to build it though and the quoted $200 or something to build it but I think thats just becaues they didnt want to do it.

http://www.temperature.com.au/Products/Sol...tateRelays.aspx

TCSSRR2540 is the part number

If you get one let me know how it works out.

 

[ramu_gupta]

I'd do what Thirsty says.

I use two 2400 W over the side immersion copper coiled heaters, small compact units which bring my wort up to a great rolling boil in no time at all. I just place a length of timber across the top of my kettle and hang them over it and secure using small grip clamps.

To reduce evaporation losses, I turn one off and the other is able to maintain the boil if I then cover some of the kettle opening.

Cheers

 

[cdbrown]

Ramu - where did you get the elements from?

 

[ramu_gupta]

A friend of mine bought and imported them from O/S. I'll have a chat to him and see if he can bring in some more if you are interested.

 

[leiothrix]

Thanks all for the replys people.

@Yorg - I've got a 15A outlet solely for my brewery, so I've got plenty of power available. I think I'll be fine with a nut, washer & silicone gasket. I have a PID & 40A SSR to bring the water up to mash temp, but I was worried about having a way too vigorous boil

@Thirsty Boy - My pot already has a hole in it, so an immersion heater is kinda out for me. It also saves me from forgetting to turn it off when pulling it out of the pot or something. My pot is a 50L robinox, so has plenty of surface area. I tried a 2200W element in it and it brings it up to around 98* with the lid on. I don't mind making the electronics, but I don't have a CRO and am a bit worried about filtering.

@Yogi Bear - The part that you listed is a solid state relay. It will turn the element on and off, but won't control the temperature by itself. I already have a 40A SSR. And just FYI, you can get them a lot cheaper off ebay (40A, DC input, $23 inc. shipping). And you probably want one with DC input control. Thanks though.


What I'm thinking of doing is:
* Purchasing the 3600W Incoloy 800 element
* The PID will bring the strike water up to temperature.
* Since I BIAB, the element will be off when mashing. The pot is covered in camping mat, and I can wrap it in a blanket as well
* For boiling I will run the element flat-out until it reaches boiling, then cut the power down so I don't have a really stupid boil rate.

I figure I can use one of the alarm relays on the PID to automatically turn on the power controller when the wort gets up to say 97*.

For power control, I'm thinking of using a 555 hooked up to the SSR. I'll have a cycle time of say 5 seconds, and just vary the mark-space ratio. So for 50% power it will be on for 2.5s, off for 2.5s, 75% power is on for 3.75s, off for 1.25s, etc.

Any comments on the power control method? I have used PWM on DC loads, but don't think it will be as easy on the AC load due to having to do some synchronising with the mains 50Hz cycle. With the method I proposed don't really care too much if it is 25ms off either way, and it will stop the SSR switching as much.

One thing I'm slightly worried about is the SSR I have doesn't say it's zero-crossing. Since I'm switching a purely resistive load, I'm guessing it doesn't matter too much. Maybe I should put a 250VAC capacitor across the element? Maybe I'm over thinking it.

Thanks,
Rob.

 

[Yorg]

Are you certain you don't already have the functionality for the power control in your PID unit?
As I mentioned, mine can be set to provide PWM at rates that aren't in microseconds, so not too rough on the SSR. In other words, the settings allow it to not be in PID mode, but a constant on-off% regardless of temperature - just as you are proposing to do with your 555.

 

[leiothrix]

My PID doesn't appear to have a manual mode. I can switch the display to see the percentage power output, but can't control it

Rob.

 

[Yeastie Beastie]

I am looking at doing exactly the same thing so I am watching this thread very closely.

For those, like me, who are new to all this "control" equipment could someone please explain in simple terms all the jargon.
I got lost at SSR & Pulse Width Modulation and that was only the second post LOL :unsure:

What I want to do is, in simple terms, is fit a screw in 3000W element, stick a probe through the wall of my pot to take temp readings (PID ???), and have a box/thermostat thingy mejig turn the element on and off to control temp.

I just think it would be handy for those making the move from the gas world to the electric world.

Damn gas was easy.

Cheers
YB

 

[leiothrix]

Ok -

SSR - Solid State Relay. It is like a mechanical relay (i.e. a switch), except it has no moving parts. The one I am using takes a small DC voltage and will switch up to a 40A 250VAC load

PID - Proportional-Integral-Derivative. Wikipedia will give a full explanation of that one. Basically it is an intelligent way of heating the strike water to the desired set temperature. Some of them have ramp/soak functions as well so if you use a RIMS/HERMS you can tell it to for example heat to 50*C, wait for 10 minutes, then heat to 64*C for 1 hour, then heat to 100*C for an hour.

PWM - Pulse Width Modulation. Basically the load gets turned on and off to limit the power going to it. For a cycle time of 5s for example, 50% power it will be on for 2.5s, off for 2.5s, 75% power is on for 3.75s, off for 1.25s, etc.


Some of the PID controllers have a manual mode which basically does the PWM part as well, but mine doesn't so I'll have to build it.

Rob.

 

[Yeastie Beastie]

so if you use a RIMS/HERMS you can tell it to for example heat to 50*C, wait for 10 minutes, then heat to 64*C for 1 hour, then heat to 100*C for an hour.

Sorry to sound uneducated on control devices but how do you "tell" it to do this. Is it via manual settings or via computer etc.


All new to me.

EDIT: Thanks heaps too, becoming clear now.

 

[cdbrown]

Buttons on the front of the PID to select various settings.