Kettle size versus heater element size

I've checked through many threads but failed to see anything on this.

Basically I want to shift from Gas to electric, and I also want to increase my brew size. So I'm wondering if there is any guidance anywhere here, or else where on how to match the element size to the size of the boil kettle, ie what watts are required for what litres? I see that a 10 galllon kettle has been fitted with a 4550watts heating element on one thread. I looking at brewing about 200litres (or 45 gallons).

Apologies if this is already on a thread somewhere.

I have a 45 gallon BK with two heating element ports on order. The reccomendation I was given was to use two 5500 watt elements.

My BK is a 55 gallon drum. I make 35 gallon batches. My preboil volume is typically about 43 gallons. I have two 4500 watt elements. After I bring the wort to a boil, I turn down the elements to 90% power. I would not want less than 9000 watts. Next time I replace the elements, I may switch to one 4500 watt element and one 5500 watt element. You are somewhat limited by the size of a 50 amp GFI breaker. You could run two 5500 watt elements (46 amps) but then it will be cutting it very close to run a pump or two on the same breaker.

I btu is about 3.4 watts. I use a 60,000 BTU propane cooker for 15 gal kegs and it is really fast. That comes out to about 17,600 watts so you would need some kind serious electrical setup to equal a propane cooker. I brew outside, which is not an option for everybody.

The efficiency of a propane burner is about 25% in getting that energy to the pot compared with 100% for an immersion heating element.

WOW, mini-ghost thread!

For anyone that found this thread via the search

You want to use this guy's Electric Heat Spreadsheet:
http://www.gnipsel.com/beer/software/beer-software.html

and/or listen to the above posters

I'd be real careful using that spreadsheet.

Insulation and diameter of opening on the lid can have huge effects on efficiency. If you are just heating mash water, you can achieve pretty high efficiency if well insulated and the lid is on. Almost all of the energy goes into the water. A little lower power means it just takes longer to get to temp.

However, for doing a full boil, consider that heat rises. Most of the heat will go out the top. And you gotta keep the top off to eliminate DMS.

The larger the diameter of the pot, the worse it gets. Remember, area = pi*R^2, meaning the surface area that loses heat goes up with the square of the radius.

So it's the boil that's most critical, so when comparing with another system, check the radius of the boil vessel. If yours is larger than the system you are comparing to, you'll need more watts.