What elements for 300l boiler

[simon12]

I have had made a 300L boiler that can have 2 standard size immersion heater elements. I suspect 2 x 3Kw elements will not be enough to get it to a boil in a reasonable time, can anyone confirm this and recommend what elements I could get. Do I need 2x6Kw or would 1 x 6Kw & 1 3Kw be OK or do I need to go even higher or add more elements. Also what would you recommend to insulate it a bit.
Thanks in advance for any help.

[Bern]

http://processheatingservices.com/water ... alculator/

Not sure if this can be applied to wort might give you an idea though

[mojonojo]

If i had a calculator on me the theoretical max formula would be KW = (Volume in L X Temp rise) / (790 x time in hrs)

but fag packet maths says about 20,000KW of energy to raise the temperature - going to need some more elements and a new ring main/400v/3phase supply

[Pinto]

If i had a calculator on me the theoretical max formula would be KW = (Volume in L X Temp rise) / (790 x time in hrs)

but fag packet maths says about 20,000KW of energy to raise the temperature - going to need some more elements and a new ring main/400v/3phase supply

This - at 300 litres. you're talking three phase electrickery to keep the cost/load sensible.

[darkonnis]

For heating, you're looking at something like a 9kw and a 6kw element? You might get by on 2*6kw elements if its well insulated. It's hard to say really as it also depends how much of a boil you want, if you wanta strong rolling boil, you need much more power than something that simmering on the surface.

For insulation you can use pretty much anything, just depends on your budget.
Armourflex is pretty good and come in a roll. It's water proof and dead easy to work.
towels also work and can be quite cheap
camping mats / yoga mats
you can use the cheap bubble foil rolls from B&Q to make an air gap of about 2" then use expanding foam to fill in the gap. This is the cheapest way its just a bit of a faff on. Do the foam one layer at a time and leave for atleast 30 minutes to harden before adding another layer.

[simon12]

Thanks guys as always on here very good info very quickly. 3 phase is not an option so from what I can tell 2 x 6Kw elements is my max so I will try to go crazy with insulation.

[Pinto]

Thanks guys as always on here very good info very quickly. 3 phase is not an option so from what I can tell 2 x 6Kw elements is my max so I will try to go crazy with insulation.

Dual radial circuits in 6mm2 cable, individual 32A breakers and 32A rated blue commando outlets then for 6kW loads.

[dloper]

I use 2 x 3kw elements and it takes 3 hours to heat 200 litres from 12 degrees C to 80 degrees C. To bring 225 litres to the boil after sparging, I switch on the elements as soon as they are covered. It takes a further 90 minutes to come to a vigorous boil. The kettle is insulated with 50mm Kingspan covered with radiator foil and is barely warm to the touch.

[simon12]

Is that kingspan stuff flexible? Is there any reason I couldn't/shouldn't use a small gas burner and 2 x 3Kw elements. The boilers base is 2mm 316 stainless steel is that thick enough to use gas as well? Thanks all for the help on this.

[mojonojo]

No Kingspan is a rigid foam type insulation

[sbond10]

No reason why you can't just use a paella burner other than insulation material s that can be left on when heating with the burner

[Pinto]

No reason why you can't just use a paella burner other than insulation material s that can be left on when heating with the burner

Rockwool is the only heatproof / flame resistant insulation medium that comes to mind, and even then it'll need a metal containing collar to keep it in place - so you'd basically be building your own bergland pot.....

[dloper]

Is that kingspan stuff flexible? Is there any reason I couldn't/shouldn't use a small gas burner and 2 x 3Kw elements. The boilers base is 2mm 316 stainless steel is that thick enough to use gas as well? Thanks all for the help on this.

I clad the kettle by cutting the kingspan into 4 inch vertical strips, with the cut angled slightly to take account of it going round the kettle. It's held in place by metal sticky tape. A layer of radiator foil wrapped round the outside tidied it up. I chose electric because a gas powered kettle was so difficult to insulate.

[simon12]

Thanks again all for the help, the unit I was looking at has fallen through so I may still get somewhere with 3 phase and its al on hold until I do.