3 ms·
In some places, India for example, hot water is sometimes supplied by a smallish reservoir at the showerhead. The reservoir's normal state is full of tap-temper
by wolverine876 3y ago
In some places, India for example, hot water is sometimes supplied by a smallish reservoir at the showerhead. The reservoir's normal state is full of tap-temperature water. For a hot shower, you turn on the reservoir's electric heater; it warms up (pretty quickly - think of electric kettles, and I don't want to shower in 100 deg C water) and you turn on the shower.
I've always wanted something like it at home; it seems much more efficient than a central hot water heater that's always warming the water. (I've also read about at-the-spigot devices that heat water like a coffee maker, with water running past something hot.)
I wonder how the heat capture of wastewater could work with it. It becomes a sort of closed loop hot water device, with heat exchanged with showering humans, the capture device, and the electrical device to top it off.
- soperj 3y agoWould work the same, since you're still supplying hot water to the sewers.
- wolverine876 3y agoI'm saying the sewer-bound water's heat could be captured and used for the reservoir.
- hinkley 3y agoI don’t know what current wisdom is, but when these were new they (eg This Old House) would suggest putting one at the master bath and maybe the common bath, then run one for the rest of the house. Effectively daisy chaining two of them for piping hot showers, but still warm enough for the washer and dishwasher. Pretty sure the deal was that none of them could really pull a couple gallons a minute at full temperature at the time.
- wolverine876 3y ago> Pretty sure the deal was that none of them could really pull a couple gallons a minute Why not just run them in parallel? If you need more flow, just hook up two or three or N in parallel, feeding the same pipe?
- hinkley 3y agoHome plumbing doesn't generally do multiple pipes. I wouldn't know if that's a code thing or just a complexity thing. But my understanding is that the heat output of the inline heaters is proportional to flow rate, so you aren't achieving much by running them in parallel instead of series. It's not that the early devices couldn't handle 3gpm, it's that they couldn't heat 3gpm, so you got really warm water but not hot water. No idea where things stand now.
- wolverine876 3y agoThanks. So the limitation is available power (to heat the water in that location)?
- hinkley 3y agoI’m really not entirely sure. I haven’t been around one since I traveled overseas and that’s been a while now. My new place has a new furnace and the old one we never got around to doing improvements so I just remember the old complaints. Thermal conductivity seems likely. How many feet of pipe can you cram in there, especially if you have to insulate so you don’t catch the building on fire? Or can you make a 3d counterflow system so you don’t have to insulate at all? ETA after further reflection, I believe they generally worked better in Europe and that would most likely be down to 220 vs 120, so you may be right about power density.