more just-in-time hot water
Saturday, November 11 2006
The Titan Heater I installed recently in the basement has a made a big difference in our Firstworlditude. Without it, we were often hostage to weather conditions and occasionally found ourselves taking uncomfortably-cold showers. Gretchen, who actually has to leave the house regularly to interact with others, bore the brunt of this imperfect condition. The tankless heater, combined with a large storage tank, is perfect for our needs. Even if the sun hasn't shone in days, most of the water in that tank is warmer than well water (51 degrees), and often the tankless heater doesn't actually have to use that much energy to raise its temperature to one suitable for showering. I can always tell when the tankless heater is doing its thing; the high-amperage pulses of power it uses to meter out its heat make the lights throughout the house flicker noticeably, like they do on Friday Nights around midnight in small Texas towns located near maximum security prisons.
The idea of heating water in real time as-needed (as opposed to heating it beforehand and storing it in an insulated tank) makes intuitive sense, unless there is some advantage to be gained by the leaking of heat from the stored hot water. We've yet to fire up the household boiler and the laboratory is consistently the warmest room in the house, heated as it is by a large (if insulated) coffee urn and whatever computers I have up. But in the summertime that waste heat is completely useless and it makes sense not to generate it in the first place.
With this in mind, I've decided to build myself a just-in-time water heater for heating water to a temperature suitable for a cup of tea. With such a device, I could get rid of the coffee urn completely. I actually have most of what I need to build a just-in-time heater. At its heart, the device would include a high-wattage electric heating element. I have several such elements, all of them removed from old electric coffee makers. Today I ran an experiment to determine if one of these elements is powerful enough to heat water at a reasonable flow rate, the kind one would want to use when filling a tea cup. I rigged up some hoses and plumbing pieces and ran an experiment using a tiny needle saddle valve, the kind used to attach a refrigerator's icemaker to household plumbing. It has a slow flow rate, but one almost suitable for filling a tea cup. It turned out it was much too slow for the coffee heating element I was using, which quickly filled with steam and developed vaporlock. I'll have to get larger valves, though still smaller than the ones I have on hand.
This evening Gretchen and I watched The Dangerous Lives of Altar Boys. For all the animation woven into it, the movie had an unusually hyperealistic quality. I don't know if I've seen a film that so perfectly captured the interplay of reality and fantasy in the lives of kids this age. Unfortunately, though, the film's final 20% had a hurried, contrived quality at odds with the 80% that had preceded it. With creative works, the 80-20 Rule should never be used for guidance as to what is good enough.
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