240V HLT 4500W heat up time experiment

[Kbar]

Built my Minibrew based HLT with a 240V 4500W element. Timed to temperature rise from 48F to 165F. Accomplished that in 42 minutes. Ran the calcs based on a formula found at a water heater manufacturer's website (Volume x temp diff)/(372 x Heat up time)*1000 = element wattage required.

Based on 42 minutes or 0.7 hours, the formula suggested a 4493W element. Not bad.

[codewritinfool]

Based on your numbers, your volume is about 11 gallons?

[Kbar]

Good Stuff code.

Yes, left out some things. Ambient was 47F, 10 gallons of water total, full circluation pump flow as well. Thanks for the reply!

[ajdelange]

You had 10* 8.34 = 83.4 pounds of water. You heated it (165 - 48) = 117 °F which required 117*83.4 = 9757.8 BTU which at 1055.05 joule/BTU equals 10295024 joule. As these were delivered over 42*60 = 2520 seconds the rate of delivery of heat to the water was 4085 joule/sec = 4085 watt. If the heater produces 4500 watts at exactly 240 V and the line voltage was exactly 240 V then the remaining 4500 - 4085 = 415 watts went into the room as heat lost through the walls of the container, the pump and the tubing, heat of vaporization and i^2R losses in the wiring and you would have 4085/4500 = 90.8% efficiency. OTOH if the line voltage drooped as little as 10 V a 4500 W heater would only produce 4123 W heating and the efficiency would be higher.

[Kbar]

AJ, measured voltage as well, and it was 238V at element terminals. FYI.

Mash Tun is a Minibrew 15 Gallon system, 0.375" wall, assuming Polypropelene.

Thanks guys!

[mordantly]

and how much did the elec. cost for this? ~$0.36?

[foomench]

My electricity is $0.06x / kwh, so that would come just under 20 cents. Nice to put that into perspective compared to propane.

[mordantly]

nice!