Shower Timer question......

I think you need to think this through some more. Do you really want to leave people in the shower, dripping soap, with the water off? At the very least, don't turn the water off entirely, but just drop to a low pressure. After a long and unmistakable warning.

What are you trying to accomplish, and who is your target user?

First thought... 2 monostables + logic

One MMV controls the shower ON time. The other MMV controls the shower OFF time.

D from BC British Columbia Canada.

What you want is something that shuts off the hot water heater when the shower is running. Shower off, water heats up. Shower on, limited amount of hot water - then you get a cold shower.

Flow sensors are cheap, and you can wire it in with the heater's temperature sensor wire.

My target user? well........I want to limit the shower times of a few teenagers I have here. All the talking and what not has had no results. I agree that I should either turn off only the hot water and/ or first limit the flow as a warning. Turning off the water heater as mentioned in a reply won't produce the results I'm looking for. The water heater is a 45 gallon tank style.

My recent in depth electronics experience is lacking......I do however some leftover knowledge of my training in the US Army years ago and my

1 year stay at a tech school. I still work in repair of basic 12vdc and 12vac circuits. Furnaces and such.

So you may have to hold my hand a little on this one.

That depends on the size of the heater. In the EU, I know that they use small tank heaters, or even demand heaters. But some of us in the US have 80 gallon tanks. Shut that off and you've still got an hour's worth of shower.

I like the previous poster's idea to shut off the hot (give them a 3 minute warning beeper). Better yet, measure the time of flow and count down only when the shower is running. My shower has a shut off to cut the flow until you need it to wash/rinse.

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Paul Hovnanian	paul@hovnanian.com
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You could try putting the *lights* on a timer.

For the hot water heater, you could add a solenoid-type bypass valve. The hot feed becomes immediately cold.

Solenoid valve and control it with some circuitry. The user starts the timer with a well-insulated momentary pushbutton switch from outside the wet area (for safety). The shower runs for x minutes, then pulses the hot water to off for a few seconds as a warning, then allows the shower to run for another period of time (a minute?) to allow the user to rinse and exit. The circuit enforces a delay after the end to prevent re-triggering for 10 more minutes.

You may want to consider what happens if the user leaves the hot water tap on, but the water is turned off by the solenoid. You may not wish to depend on the solenoid to control the water entirely (and it might not be to code, and your insurance might not pay off if there was water damage when nobody was around-- which could run into tens of thousands of dollars or more).

Easiest way would be a small PLC or a bunch of timer relays, but that would be fairly costly. A small microcontroller or some timers. Maybe someone here feels like drawing up a circuit based on 4000-series CMOS for you, but consider the other issues.

Best regards, Spehro Pefhany

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That shouldn't be an issue. The shower fixture is a single knob moen. So the one knob controls both hot and cold. The kids are so trained, after years of use, that I am sure they would reach down and push the knob in to turn off the "now cold" water once the solenoid closes to turn off the hot water supply. If they don't? Well then the cold will just continue to run. My original thought was to actually control ONLY the hot water supply, warning or no warning.However, I do prefer the warning without making things too complex.

That would be GREAT! Thanks for all the input so far!

I have seen such contraptions at campgrounds and such. Surely they must be a commercial product. You know the deal, 1$ per 5 minutes or so. If you want to take long hot showers for "free", sign up to a gym. I take mega long showers there and so I only use my home shower 2-3 times a week.

I wonder if you can do this mechanically, and not involve electronics? Also, it might be better to have two "switches". The first slows the water, the second cuts it off. Leave enough time in between to at least rince off.

-mpm

Same here. They either don't shower for days or shower for 30 to 45 minutes.

You need a electrically controlled valve to turn off the hot water line. Sprinkler valve might work, but not sure if it will be a problem with hot water.

12V might not be enough, perhaps 24V to 48V valve.

Dedicate a real small water heater to the shower. Like something meant to install under a sink. So after Mr. or Ms. Teenage Waterbug uses about ten gallons, it gets cold, and no more hot water for a while!

Naw, just turn off the hot water... Leave the cold running!

IMHO, in agreement, this is not a very bright idea--close to living dangerously actually. At least lock up all the sharp knifes when you set this thing up!

I have seen a unit available. Retail is over $200. Just figured I could find a quick simple explanation and possible diagram on how to assemble such a device, including the circuitry involved.

Not a bright idea? AND hiding the knives? LOL.......from whom? The teenagers? LOL..... I am willing to deal with whatever fallout develops WHEN I start limiting the showers. Knives or no knives!

Thanks for all the help. I am still intent on building a device that will do what I want.

Described much better by Spehro Pefhany in response to my original post:

Solenoid valve and control it with some circuitry. The user starts the timer with a well-insulated momentary pushbutton switch from outside the wet area (for safety). The shower runs for x minutes, then pulses the hot water to off for a few seconds as a warning, then allows the shower to run for another period of time (a minute?) to allow the user to rinse and exit. The circuit enforces a delay after the end to prevent re-triggering for 10 more minutes.

Start by looking in gardening supplies. Here's one example (wrong country, but you get the idea)

- What about those valves that are used in automatic clothes washers? They're pretty simple and inexpensive.

I think they work on 120VAC, so not sure if that's practical for you application, but maybe?

Even if you can design this, the logistics will be a mess. Where do you mount the controls? Where do you splice in the valves. This is a hell of a lot of work.

turn the temp setting in the hot water heater down so that you have to set the valve to almost full hot to get to shower temperature ... that will consume the water faster and use a little less energy, the water will gradually get colder as it is consummed... and low flow shower head...

If you spend $200 for controls and valves etc, did you figure how long is your payback time?

Mark

I recommend a valve for a washing machine or a dishwasher. Inexpensive, available and known to be able handle the job, probably

120 Vac though, so an SSR is needed to control it.