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| Thread ID: 71115 | 2006-07-27 01:18:00 | Hot water cyclinder:How does it work and how much power.... | lance4k (4644) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 473887 | 2006-07-28 04:30:00 | So to reduce electricity costs, you need a means of causing harmonics. Harmonics will drive resistive heating elements, so if they won't register on the meter ... :D Joe: our domestic water heaters boil only if there's a serious (thermostat) failure, or if a "wetback" (a heating coil in a fireplace) adds too much heat to the water. My only mention of steam boilers was in reference what can happen in the fault case. That questioner was asking about the pressure relief valve on a "mains-pressure" cylinder ... which could be a seriously dangerous device. It's at 100 psi or so normally, so the boiling point is high. If no taps are on, a thermostat failure could produce a dangerous pressure increase. So there's a pressure relief valve. Older cylinders are fed from a header tank, and have a vent pipe open to atmosphere The maximum possible pressure is about 10-20 ft water gauge ... say 5-10 psi. So you can get boiling water washing your roof, rather than an explosion. |
Graham L (2) | ||
| 473888 | 2006-07-28 06:05:00 | For pressure and temp over-runs, we use a T&P Valve . . . temp and pressure to protect the home and occupants . Nothing like having a crater where it once existed . Actual water temps here on domestic water heaters is topped out at about 165 F . So far there are no requirements for mixers to limit the water temp to 140 or so at the taps, although I see that coming soon on new builds and repair/replacements of heaters . Losses of economy that I mentioned for using electricity have to do with the generation from oil-fired boilers or nuclear generating stations or hydro-electric generation, the delivery to the ultimate homestead and . . . . . . . . . . . . . . . . all the aformentioned are scorned upon by the tree huggers . . . what do they think? Is the good fairy gonna drop off a bucketfull of electrons every night at their homes? Most in the US are natural gas fired, others are propane and a smaller percentage are electric . Solar pre-heaters have not worked out well in the US . . . they are expensive and a service nightmare for homeowners . Maybe if they get a lot more therms captured and they get some more reliability for other than heating swimming pools with a thermal siphon . Your harmonics trick reminds me of a guy who had placed large loops of wire in coils under a transmission line to pick up the induced electricity from eddy currents on the wires . He got away with it for years via the FCC ruling that any emissions into the ether would be fair game to anyone who could receive them . The law changed, or he died or had his knees broken and he went away with a snivel . It is now illegal to harvest or gleen electricity via induction . Others have placed induction coils around the meters to slow the wheel from turning the gears in normal speed . This works pretty good for people on remote radio-linked readers where the electric company doesn't have to physically read the meters but get the numbers from a transmitter when they are in range . . . about 30 yards or so . |
SurferJoe46 (51) | ||
| 473889 | 2006-07-29 00:14:00 | I don't know why people freak out so much about the token losses of heat from a HWC. Mines installed in my bedroom, so any losses warm my room. Given most people heat thier rooms, why is it so bad that a little heat got into their lives? | personthingy (1670) | ||
| 473890 | 2006-07-29 00:29:00 | I don't know why people freak out so much about the token losses of heat from a HWC. Mines installed in my bedroom, so any losses warm my room. Given most people heat thier rooms, why is it so bad that a little heat got into their lives? Fazackerly ! I had to fit a small heated towel rail in the airing cupboard after an insulating blanket was wrapped around the hot water tank :D Now we have an even better insulated new tank, and there would be no warmth in the airing cupboard at all if it wasn't for the small heater. On the other hand, the cupboard heater can be switched on and off as required, so all in all, a well lagged tank +extra heater is better than a poorly lagged tank. |
Terry Porritt (14) | ||
| 473891 | 2006-07-29 01:25:00 | The losses aren't token with an old cylinder "insulated" with a bit of underfelt . Since most old cylinders are too small by modern standards, the themostats are turned up, and the losses increase considerably . The "airing cupboard" made some use of a bad situation . Better insulation is much cheaper . Mains pressure cylinders, which allow smaller pipes, so less hot water cools in the pipes when the taps are turned off, and copper pipes which are easier to heat up than traditional cast iron water pipes, both help . (Uranium pipes would be even better than copper . :D It's got a specific heat of about 0 . 12 against 0 . 38 for copper . I suppose George W would object to that . :( ) |
Graham L (2) | ||
| 473892 | 2006-07-29 02:49:00 | Your harmonics trick reminds me of a guy who had placed large loops of wire in coils under a transmission line to pick up the induced electricity from eddy currents on the wires . I think that story might just be an urban myth Joe . Firstly it is nothing to do with eddy currents, and secondly, the coupling distance would not be closer than about 5-7 metres and air-cored tranformers are very inefficient at 50/60Hz . You would certainly generate some power off the loop, but I doubt that you could get useful levels, though GF may astound us all with some calculations if/when he spots this . With a big enough coil with plenty of turns you might get sufficient power to light a couple of small bulbs or to run your cowshed radio, but that's about it . As for getting away with it, I'm pretty sure that any substantial coupling would put a bump in the line impedance characteristics and be traceable back to within a few hundred metres or less of the perpetrator's location . Cheers Billy 8-{) Edit: Busted: Stealing power via a coil under power lines . For this myth the MythBusters created a large coil of wire, and wrapped it around a PVC pipe box . They then hoisted it underneath powerlines in order to "catch" some electricity . They were able to obtain about eight millivolts of electricity . They determined that siphoning a practically useful amount of electricity in such a manner would require thousands of pounds of wire, and would be extremely impractical and dangerous, as well as being illegal . |
Billy T (70) | ||
| 473893 | 2006-07-29 06:12:00 | err billy...... do you remeber the farmer who the electricty company was trying to take to court some years ago because he rigged up some big coils on his cow shed roof and ran his cow shed of it. he was directly under 66kv lines afaik. not sure what was the outcome. | tweak'e (69) | ||
| 473894 | 2006-07-29 07:29:00 | err billy . . . . . . do you remeber the farmer who the electricty company was trying to take to court some years ago because he rigged up some big coils on his cow shed roof and ran his cow shed of it . he was directly under 66kv lines afaik . not sure what was the outcome . I don't recall that tweak'e, and it may be just another local urban myth as well, or he may have attempted unsuccessfully and been caught . You are a tech so you will know about induction & magnetic coupling . A power line passing overhead represents less than a single turn, and the magnetic field strength is not high at the distance that the coupling coil must be located away from the line . In addition, a typical 66kV line does not operate at a very high current, and a multi-turn coil should operate as a step-up transformer, not a stepdown . Personally I can't see it working, but I'm open to serious calculations that show it could . Cheers Billy 8-{) |
Billy T (70) | ||
| 473895 | 2006-07-29 09:09:00 | dunno on the math, i havn't done that for a looong time. i remember the story ran on the news years ago. | tweak'e (69) | ||
| 473896 | 2006-07-29 09:35:00 | There used to be an "urban legend" circulating back in the 50s, I think I heard it at the Slade Radio Society in Birmingham, that someone who lived fairly close to the 400KW, 200Khz, long wave BBC transmitter at Droitwich in the UK was able to draw off a sizeable amount of power from the magnetic field component by means of a large frame aerial. The culprit was apparently detected by the station engineers noticing unusual variations in power output, or something. That sounds much more plausible than a coil under high voltage transmission lines. But I don't know how true it was. |
Terry Porritt (14) | ||
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