need to replace Burned up heating element

[Swags]

Our brewery uses an electric heating element for the hot liquor tank.

We've burned up two of the Mcmaster Carr stainless steel units...about $280 / each. I don't know if it's salts, acids or what that's causing the corrosion and ultimate failure of these elements, but I would like to get a recommendation on a similar unit.

we sometimes put lactic acid, calcium chloride and / or calcium sulfate in the HLT.


Our wiring is 3 phase, 208V, i believe max amperage of 25V for 10kw unit.

thanks for any input.

McMaster Carr: model 3656K162 Screw-Plug Mount Immersion Heater, 304 Stainless Steel, 240V AC, Three Phase, 10500W, 28" Long

[TGTimm]

I don't have time to look up that part right now, but the important thing is: Is it an ultra-low density unit? If not, then it's likely that scale--even transient scale that will be seen as little tube-ish bits on the bottom of the HLT--may be causing your element to burn out prematurely. The fastest way to kill an element is to let it get buried in scale, or, worse yet, let it run dry. You do have a low-water cut-off to prevent this, right?

Since you're running a 240V element on 208 power, it's drawing ~50 Amps, not the 44 Amps it's rated at. This can also cause premature failure.

[rdcpro]

Since you're running a 240V element on 208 power, it's drawing ~50 Amps, not the 44 Amps it's rated at. This can also cause premature failure.

Actually, it's the other way around. An element rated for 240 Volts will draw less current when powered at 208 Volts. Instead of using the power equation, use Ohm's law. An element rated at 10KW at 240V doesn't have the same power at 208V. Probably the resistance isn't the same either, but it's close enough for this:

Find Current of 10.5KW at 240V
P=IV
P/V = I
10,500 W / 240 V ~= 44 A

V=IR
V/I = R

So,

V₁/I₁ = V₂/I₂

I₂ = V₂ / ( V₁/I₁ )

I₂ = 208 V / (240 V / 44 A )

I₂ = 38 Amps

So, the actual power of that element at 208 V is:

P = IV
P = 38 * 208 ~= 8 KW

EDIT: Sorry, those calcs are for single phase, but when I look up the element, it's actually 3 phase. So the equations are similar, but with a constant for correction. In other words, Ohms law for three phase systems is V = Sqrt(3) * I * R

Find Current of 10.5KW at 240V 3ph
P=1.73 * I * V
P/(V * 1.73) = I
10,500 W / (1.73 * 240 V ~= 25 A

And then Ohms law looks like this.
V=1.73*I*R
V/(I*1.73) = R

So,

V₁/(I₁*1.73) = V₂/(I₂*1.73)


To the OP: If you're adding calcium chloride, you might be getting chloride stress or chloride pitting corrosion. This can happen very quickly, especially with 304 SS. There are alloys that are resistant to it...Inconel is one, if I recall correctly.

https://en.wikipedia.org/wiki/Inconel

Maybe you should use the Incoloy element instead? https://www.mcmaster.com/#3656K93

Regards,
Mike Sharp

[TGTimm]

How did I get those numbers backwards? Must not have had enough coffee this AM. And, indeed, I forgot the correction for 3-phase.

[TGTimm]

I'll also mention that SS is a very poor conductor of heat, which might be contributing to your problem. We used to heat our HLT with electric element, and simply used 6 kW low-density home-water heater elements. They lasted for a few months to a few years, and were cheap and easy to replace.

[brewmaster 2011]

I'll also mention that SS is a very poor conductor of heat, which might be contributing to your problem. We used to heat our HLT with electric element, and simply used 6 kW low-density home-water heater elements. They lasted for a few months to a few years, and were cheap and easy to replace.

i got a quick question about this subject. If you added lactic acid to the water like in an electric boiler using ss element, would that help prevent scale build up on the element?

[rdcpro]

Must not have had enough coffee this AM.

Lucky for you, the US Military has your back:

https://qz.com/1296394/the-us-armys-new-algorithm-will-tell-you-exactly-how-much-caffeine-to-put-in-your-body-for-peak-performance/

Regards,
Mike

[FourSeasonsBrewing]

Ive had very good luck with these....

http://www.brewmation.com/Components_Heating_Elements.cfm