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Cold Showers.

Discussion in 'General Electronics Discussion' started by eptheta, Aug 29, 2011.

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  1. eptheta


    Dec 20, 2009
    My College won't let me have hot (and for that matter, remotely warm) water in the showers. They want me to rely on a single faucet to fill a bucket of hot water every single morning at 6:30 am. I can't do that.

    I wanted to know the feasibility of creating a sort of shower head attachment so that I can take a good warm bath. (I was thinking no further than resistive heating)
    I'm blank right now, because I have no way of knowing how much power this heating element would need and if the volume flow rate of the shower is slow enough to heat up the water appreciably.
    I don't even want the water hot ! Hell, I'd settle for lukewarm !! Anything is better than having a hailstorm in my shower cubicle.

    If anyone has any ideas on this matter, then please do help me out here. It's not very pleasant having to spend 10 minutes everyday after my bath thawing myself.

  2. davelectronic


    Dec 13, 2010
    Cold showers

    Hi there.
    Thats terrible, what a place, hope the teaching is not as cold as the showers.
    Any way heating a constant flow of water low voltage would not be feasible i don't think, i might be wrong, and mains power draws a fair amount of current, some where in the Kw ball park, then if the college monitor electricity use, it wont be long before they hunt you down in search of the power hungry offender, portable gas appliance and a warm wash down is the best i can come up with, sorry, unless you can draw power and get away with it.
    What a mean college, no reflection on you, but to put a student through that is awful, oh hang on, is this special forces training, cold showers in the morning early grueling start, no only joking i don't think its that, although its a possibility, if it is that and you come up with an idea you might get a commendation for being resourceful. Dave. :)
  3. eptheta


    Dec 20, 2009
    Turns out, a majority of the students are okay with this.
    This might be an "Oh, that's why" moment, but it really shouldn't have to be this way. I'm in an engineering college in India, most consider this statement itself a 'sufficient reason'. India has a reputation for these kinds of grim scenarios, but in a place where all the classrooms and lecture theaters are air-conditioned, we are given the bare minimum for living a comfortable life.
    I wouldn't call it a 'mean college', it just seems that their priorities are a little biased against comfort. :D

    Haha, I hope so too. So far (just been 2 weeks) it seems pretty good.

    2 weeks of cold showers has kind of got me to the point where I'm willing to take that sort of risk. I am worried however about the hazards drawing from a 230V source entails.

    Do you have a sort of mental concept of how much current it would take (and so a rough idea of how high a voltage it would take to heat up flowing water?) Just so I can get things into perspective.

    If you or anyone has any specific ideas, please do let me know.
    Thank you.
  4. daddles


    Jun 10, 2011
    Look up the specific heat of water in any elementary physics text; this will also give you the requisite equation to calculate the amount of heat energy needed to raise the temperature of a mass of water a desired amount (as long as there's no phase change). To calculate the power needed, you need to know the mass flow rate. Also, you need to know the efficiency of the method you use to change electrical energy into energy that heats the water. You can look this stuff up in an engineering heat transfer textbook, but you'll get mired down in things like Prandtl number, Nusselt number, etc. The basic physics will get you the minimum energy input; this can be translated into a maximum temperature rise you'll be able to realize for a given power input to a mass flow. Then comes the engineering to estimate what you'll actually be able to achieve with real parts and imperfect designs. The most efficient way to make an estimate would be to find a mechanical or chemical engineering student near graduation and ask them to help you make an estimate. Then comes experimentation and finding parts to build a real device with. My suggestion would be to first look into what can be purchased (i.e., this is a buy vs. make situation if possible).

    There are on-demand heating units that you mount under your sink, but you'll find that they require significant amounts of power. Look up "tankless water heater" for more details.
    Last edited: Aug 29, 2011
  5. davelectronic


    Dec 13, 2010
    Shower heating

    Hi again.
    There might be a member out there with a low voltage high current solution, but i can not think of one for continuous cold running water.

    A mains installation is only safe if a proper shower unit is used and installed safely, there can be no compromise with a mains voltage installation, if a low current idea out there its probably going to be a very slow flow of water rate, induction low voltage heat comes to mind from a MOT microwave oven transformer, but, and its a big but, you would need to rewind the transformers secondary winding for low voltage high current, then the induction heating pipe plus pump, low voltage as well, and the transformer must be away from the water, and grounded well, its all a lot of work, and then there are no exact temperature guarantees, any members have any ideas, ? . Dave. :) PS The induction root needs a lot of details working out, safe current consumption, voltage, induction pipe materials, pump flow control, a lot to work out.
  6. duke37


    Jan 9, 2011
    In the UK electric immersion heaters are sometimes used for heating shower water. A typical power of 7kW (30A) is used with a dedicated high current supply. Water and electricity don't mix, or mix too well!
  7. Resqueline


    Jul 31, 2009
    It's relatively common with electric shower (head) heaters in Asia.
    They're a box on the wall connected to a mains outlet and the shower hose, and turns on automatically when water flows.
    There are even smaller heaters to mount directly between the pipe from the wall and the shower head, working the same way.
    The temperature it achieves will of course depend on the flow, but luke warm is fully possible from a 10A circuit.
    The safety aspect needs to be considered (i.e. reliable grounding, and not getting water on any plugs/sockets).
    I'm sorry I don't remember any makes/ models/ names, but I'll bet they're made in China.
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Ahhh, be a man. Just have a bucket bath.

    It's one of the things I get used to when I go to India.

    Having said that, it's a lot more pleasant when the weather is hot than when it's cold.

    If you're near a sunny window you might try hanging out black plastic pipes full of water. They may heat up enough during the day to give you a warmish shower in the evening. Even better if you can sling it up on the roof.

    I'm back to India in October/November (2 weddings) -- where are you? I'll be around Mumbai most of the time. I hope my wife likes Diwali :)
  9. daddles


    Jun 10, 2011
    You equatorial folks have life easy. :p You'd feel a bit differently if it was below zero degrees F and there was a foot or two of snow on the ground. Cold showers suck in winter.

    I used to have my shop in an unheated outbuilding in our back yard. I'd trudge out there through the snow, then have a hell of a time using my lathe because the metal parts and machinist tools would freeze to my fingers (i.e., colder than your freezer will get). Think tongue on the flagpole in "A Christmas Story".

    I'd recommend being quite cautious with any line-powered device that fit to the water supply like a shower head. I've read about some very poor designs that directly expose the heating element to the water, meaning the water can be at a significant potential.
  10. jackorocko


    Apr 4, 2010
    Tell me about it, I couldn't imagine having it never get below 50 degrees out. Coldest I have ever seen was -28F.

    Maybe the college prefers their students be awake during classes, I can't see how a cold shower wouldn't wake you up in the morning!
  11. rootboy


    Aug 26, 2011
    That's what I was thinking. My sister lived off of the grid for a year or so and that's how they heated their water. In the mountains of Colorado, no less.
  12. Windadct


    May 25, 2011
    Don't build this..............

    FIll 5 Gal Bucket - I guess something like a 20L container, even a cooler and use tea boilers - 3 or 4 and PRE HEAT the water -

    Un-plug / remove the heaters when hot and suspend from the ceiling, could mix with the running cold water to adjust temp etc. ( I'm not a plumber, but I play one at home)

    Otherwise - buy a Tankless Hot Water heater like this : - OOPS that is a propane/gas model - google Tankless Hot water - I have also found some 2.5 Gal ones( not quite tankless). Many are 240VAC ( Here in the USA) -- if you are going to plug one in in the showers - please - nice way of saying you MUST) use a cord or outlet with Ground Fault Circuit Interrupter ( GFCI ).

    I'm an EE, worked on HV electrical systems (up to 15KV Live) and was my companies safety coordinator - and I can not think of a good way to home build this as a project and stay safe - even it you are OK risking your live - making something like this risks everyone's life that is in the area.
    Last edited: Sep 2, 2011
  13. eptheta


    Dec 20, 2009
    Thanks guys, I'll see if I can buy one of those detachable-heating-shower-heads, though I'm not sure If I can find it easily around here I guess I'd have to poke my nose around asking if my campus has this GFCI installed. Although that might seem awfully suspicious to them...
    Also, as luck might have it, one of the showers has a little panel leading to the mains, so If no one minds (/if no one finds out), I'll get a socket installed there.

    Yeah, I was very very hesitant to home-build this. All my electronics experience is limited to 5V DC, so making one was kind of the last resort plan. And even then, my approach was rather primitive because of how less I know--ceramic coated coils of resistive heating wire connected directly to the mains...

    That's what I told myself every morning for the first week, then it occurred to me that I have to 'be a man' for 5 years. If getting warm water means I have to relinquish my claim on masculinity, then so be it.
    I'm studying in Goa, but I'm going back home to Bombay for Diwali. Other than the deafening sounds and the asphyxiating smoke, what's not to like about Diwali !
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