Immersion Heater calculations

[Kbar]

Leave it to McMaster Carr. Years of engineering school and higher math to have most of my engineering career bottle neck down to algebraic equations. I am wanting to move to a 240V immersion heater in the HLT vs. Gas fired. I will leave the BK gas fired however. Found this equation for immersion style heaters.

V (gallons) * Delta T (F)
____________________ * 1000 = Wattage Rating of immersion heater
372 * Heat up time (Hrs)

Example - 3 Gallons of water for mash in, 60F to 168F, in 15 miniutes (0.25 hours) = 3484W or 3500W approx. Equation assumes water only. You can see their website for liquids of different densities as well. FYI

take care all!

[codewritinfool]

This may be of help also.
viewtopic.php?f=2&t=10822&p=103792&hilit=element#p103792

[Kbar]

This may be of help also.
viewtopic.php?f=2&t=10822&p=103792&hilit=element#p103792

Thanks Code!

[ajdelange]

All you have to remember is that 1 KW is equivalent to 3414 BTU/hr and that water weighs about 8.34 pounds per gallon. Thus in the example where it is desired to raise 3 gallons through a 108 °F rise the heat requirement is 3 x 8.34 x 108 = 2702.2 BTU. If this is to be accomplished in 1/4 hour then the heat input rate must be 2705.4/0.25 = 10808.6 BTU/Hr which is equivalent to 10808.6/3414 = 3.166 kw. That's all there is to it assuming 100% efficiency. The McMaster Carr formula apparently assumes 91% efficiency.

[codewritinfool]

All you have to remember is that 1 KW is equivalent to 3414 BTU/hr and that water weighs about 8.34 pounds per gallon. Thus in the example where it is desired to raise 3 gallons through a 108 °F rise the heat requirement is 3 x 8.34 x 108 = 2702.2 BTU. If this is to be accomplished in 1/4 hour then the heat input rate must be 2705.4/0.25 = 10808.6 BTU/Hr which is equivalent to 10808.6/3414 = 3.166 kw. That's all there is to it assuming 100% efficiency. The McMaster Carr formula apparently assumes 91% efficiency.

Excellent info, ajdelange. Of course, you just know I had to go plug your numbers into my equations and it came out 15.01 minutes, so I was pleased. I also admit that the geeky engineer in me had me considering, if only for a split second, where the rounding errors were.