Getting 12 gallons up to boil - Home Brew Forums

 Home Brew Forums > Getting 12 gallons up to boil

07-08-2009, 10:17 PM   #1
tkone

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Jan 2009
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hey all.

do you think 4000 watts of electric power can get 12 gallons of wort up to a boil?

i'm building out an electric RIMS and i am trying to figure out how much power i'll need to get this up and going.

also, any downsides to using the kettle as a direct-fire HLT as well?

thanks!

07-09-2009, 12:04 AM   #2
dwarven_stout
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1 BTU is the energy required to raise one pound of water by one degree Fahrenheit.

1 US Gallon = 8.3 pounds.

We'll assume 100% heating efficiency to make the math easier, and we'll assume we start from mash-out temp.

To raise a 12-gallon kettle of 160 °F water up to 212 °F would require 12 gal x 8.3 lbs/gal x (212°F − 160°F) = 5179 BTUs
Since we're doing wort instead of water, we'll guess a specific heat of ~0.95 compared to water's 1.0, giving
us a heat requirement of 5179/0.95 = 5452 BTUs

It's 3412 BTUs per kWh, so your element puts out 4x3412 = 13,648 BTUs/hour, and would take
(5452 BTUs) /(13,648 BTUs /hr) * (60 min/hr) = about 24 minutes to boil, once again assuming 100% efficiency.

Actual time will obviously depend on how efficient your setup is, but the answer to your question is yes:
you can boil 12 gallons with a 4kW element.

Reason: threw in a guess for C_sp of wort

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07-09-2009, 12:33 AM   #3
Joe Camel
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Getting wort to the boiling point is one thing, getting a good boil requires energy too as you need to put in a lot energy to transition from water to steam. If you read the Pols electric herms thread, a few brewers have chimed in that they use 5500 Watts to get to the boil and then turn the element down to 3500 W to maintain a good strong boil.

So the short answer is yes, you will get a boil and maintain it with 4000W

The RIMS part has nothing to do with the boil, though, you can use less power and lower watt density in the RIMS element. I would not direct fire an electric boil kettle, that sounds a bit dangerous to me
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07-09-2009, 02:21 AM   #4
Sawdustguy

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Quote:
 Originally Posted by Joe Camel Getting wort to the boiling point is one thing, getting a good boil requires energy too as you need to put in a lot energy to transition from water to steam. If you read the Pols electric herms thread, a few brewers have chimed in that they use 5500 Watts to get to the boil and then turn the element down to 3500 W to maintain a good strong boil. So the short answer is yes, you will get a boil and maintain it with 4000W The RIMS part has nothing to do with the boil, though, you can use less power and lower watt density in the RIMS element. I would not direct fire an electric boil kettle, that sounds a bit dangerous to me
I think what the OP is asking is if you can direct fire the HLT with propane or natural gas and have an electric RIMS. The answer is an absolute yes! I do it that way and so does the Sabco Brew-Magic. I think it would be very expensive to have an all electric RIMS because the RIMS heater element and HLT electric element may have to be on at the same time for some period. You would need lots of current for that, and frankly I don't have an extra 50 to 60 amps to spare on my service. I would have to increase my service to 250 amps. I do think the OP is a little confused though because if he is building a RIMS he does not boil anything with the element. The element simply keeps the MT at a constant temperature while recirculating the mash. A 1500 watt low density element is more than adequate for the task. Here is a schematic of my system. I do use three pumps. The only reason I have three is that I got them in a trade. Three pumps is not a necessity, otherwise, they would just sit on the shelf. I also control the temperature of the HLT electronically which is not absolutely necessary but nice to have.

Note: I have since switched the orfices on my burners to Natural Gas, so wherever it says "To Propane Manifold" please make a mental note it should say "Natural Gas Manifold".
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07-09-2009, 03:09 AM   #5
Joe Camel
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Sawdustguy...

That wasn't my interpretation, I believe he asked if you could Boil 12 gallons with a 4000W element and use the kettle as a direct fired HLT. This implies that the kettle is wired for electricity and sitting on a burner. I don't quite see the point and do see the potential for disaster. I like the idea of a dual purpose kettle, but why two sources of heat?

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07-09-2009, 03:26 AM   #6
wilserbrewer
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I do 1/4 keg batches w/ a preboil volume around 9 -10 gallons and have no trouble achieving a pretty vigorous boil in a reasonable amount of time.

edit...sorry, w/ 4000 watts

07-09-2009, 03:57 AM   #7
Sawdustguy

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Quote:
 Originally Posted by wilserbrewer I do 1/4 keg batches w/ a preboil volume around 9 -10 gallons and have no trouble achieving a pretty vigorous boil in a reasonable amount of time.
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07-09-2009, 04:03 AM   #8
Sawdustguy

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Quote:
 Originally Posted by Joe Camel Sawdustguy... That wasn't my interpretation, I believe he asked if you could Boil 12 gallons with a 4000W element and use the kettle as a direct fired HLT. This implies that the kettle is wired for electricity and sitting on a burner. I don't quite see the point and do see the potential for disaster. I like the idea of a dual purpose kettle, but why two sources of heat? Perhaps the OP could provide more information...?
Joe,

Now I am not sure what we wants to do. If you are correct, I agree that it is not the safest way do do things. On my rig, even though I don't have it drawn, I do have a burner under my MLT. I rarely use it, but I did use it once to augment the heat for a more rapid step mash. The difference on my rig is that the Mash Recirculating Heater is separate from the MLT and the burner is nowhere near it.
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07-09-2009, 12:27 PM   #9
tkone

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Jan 2009
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i would love for simplicity to be able to heat my water in the same unit that eventually does the boil.

thanks for the calculations dwarven_spirits.

the problem is i live in an apt and can't use anything that burns a fuel that isn't my gas stove, which has a hard enough time boiling 6.5 gallons even split into two pots across all four burners.

hence harnessing the power of electricity.

07-09-2009, 12:36 PM   #10
tkone

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Jan 2009
Posts: 153

but i just realized i'd have no where to drain to if the kettle was the mlt.

thanks for helping me think this through!