onyxrev Senior Member Joined: 9 May 2011 Posts: 9 Location: San Francisco, CA Expertise: I live coffee
Posted Mon May 9, 2011, 7:37pm Subject: Portable power for water heater for pourover coffee (195-200 degrees F)
Heyo! Long-time coffee fanatic here. My wife's a pro barista here in San Francisco and I've been considering getting into the coffee biz with a different angle. I'm thinking about opening up a drip coffee cart and am researching options for heating water without electricity. This search has taken me to consider using propane. The propane water heaters I can find will only go up to around 160 degrees max, which obviously just isn't hot enough. I'm starting to research building my own heater, but I have no experience in this realm and would rather not blow myself up.
Anyone else out there have any experience with something like this? Again, I'm looking for a water heater for pour-over drip coffee, not a propane espresso machine.
If worse comes to worse I figure I may be able to rig together something using a stew pot, a propane burner, some hardcore insulation, and a nice thermostat.
Joel_B Senior Member Joined: 9 Oct 2007 Posts: 1,823 Location: Pacific NW Expertise: I love coffee
Espresso: Astra Mega II Grinder: Mazzer SJ, Virtuoso Vac Pot: Yama 5 cup Drip: nope, french press Roaster: Behmor, WP, BBQ drum
Posted Mon May 9, 2011, 9:18pm Subject: Re: Non-electric water heater for drip coffee (195-200 degrees F)
onyxrev Said:
If worse comes to worse I figure I may be able to rig together something using a stew pot, a propane burner, some hardcore insulation, and a nice thermostat.
It seems the biggest hurdle here is keeping the water temp constant without constant (manual) adjustments and monitoring. None the less if you had a large enough pot, you'd be able to limit the tinkering.
Along the same lines, maybe look into jacketed containers. Basically a heat exchanger. It's used a lot in the brewing industry but not esclusively. I know in my own brewing experiences, an insulated container can hold the water relatively stable but if you're pulling from the container, the thermal loss will increase the lower the water level gets.
What about portable electricity such as a generator or a series of batteries? Don't know the kind of energy yo u'd need but worth a look.
onyxrev Senior Member Joined: 9 May 2011 Posts: 9 Location: San Francisco, CA Expertise: I live coffee
Posted Mon May 9, 2011, 9:21pm Subject: Re: Non-electric water heater for drip coffee (195-200 degrees F)
A generator would work but is noisy and large. A car battery, by my calculations, would last around 30-60 minutes :/
I'm definitely nervous about propane. There are some very nice looking 25 quart stock pots with spigots that would probably work nicely. If I built an insulated wall around it with duct piping and insulation it might be safe enough. But yeah, I hear you on the constant tweaking. One might not know how reliable it would be until one tries it.
Is that constant heating? Or is that actual maintenance usage? Is that one battery? Just brainstorming mind you, but what about using several batteries; 4 maybe? And preheat water on a stove but use the batteries as maintenance to eliminate the manual monitoring.
onyxrev Senior Member Joined: 9 May 2011 Posts: 9 Location: San Francisco, CA Expertise: I live coffee
Posted Mon May 9, 2011, 9:40pm Subject: Re: Non-electric water heater for drip coffee (195-200 degrees F)
Actually, a very high-end car battery like ones used for high-output car stereos might work. A Fetco water tower draws about 2400 watts. 2400 watts / 12 Volts = 200 Amps. I found a battery that can provide 2600 amps at 12 Volts, which, if I've done my math right (unlikely but let's pretend) potentially could run for up to 13 hours. That would be nice if it were true. I'll have to ask my electrical hacker friends if that seems right. I could pick up a spare battery, too, and charge them at night.
Posted Tue May 10, 2011, 4:26am Subject: Re: Non-electric water heater for drip coffee (195-200 degrees F)
onyxrev Said:
Actually, a very high-end car battery like ones used for high-output car stereos might work. A Fetco water tower draws about 2400 watts. 2400 watts / 12 Volts = 200 Amps. I found a battery that can provide 2600 amps at 12 Volts, which, if I've done my math right (unlikely but let's pretend) potentially could run for up to 13 hours. That would be nice if it were true. I'll have to ask my electrical hacker friends if that seems right. I could pick up a spare battery, too, and charge them at night.
No expert here, but you cant draw 200A an hour for 13 hours from a lead acid cell in the real world. Internal resistance and the resistance of the heating coil would both be factors.
In fact, realistically I don't think you can use batteries to heat water in a practical way because the voltage is too low to generate enough power in the heating coil which is effectively a big resistor.
JasonBrandtLewis Senior Member Joined: 9 Dec 2005 Posts: 6,099 Location: Berkeley, CA Expertise: I live coffee
Espresso: Elektra T1 - La Valentina -... Grinder: Mahlkönig K30 Vario -... Vac Pot: Yama 5-cup Drip: CCD, Chemex Roaster: No, no, not another...
Posted Tue May 10, 2011, 7:43am Subject: Re: Non-electric water heater for drip coffee (195-200 degrees F)
Uh, OK. What am I missing? Every portable cart that I can remember seeing that does drip uses a propane burner/stove to boil the water. How is this so difficult? You take the water off the boil, let it cool a few degrees, and brew . . . . so, what am I missing?
I (assuming I understand him correctly) believe the OP is wanting a pour over station. Doing a large air pot at a time, yes, brewing just off the boil makes sense, but doing that for every cup does not. YMMV of course.
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