Bathroom automation and waterproofing devices

Hello,

I've searched the forum, but didn't found any relevant bathroom-related projects. I want to make a shower that keeps the user defined temperature and flow. My shower mixer is a mess when it comes to manually adjust the knobs - it has two states - arctic freeze and hellish hot.
I imagine this project to have 2 valves (1 on hot water, 1 on cold water) mixing the water, 2 DS18B20 temperature sensors (1 on hot water, 1 on the mixed output) and user controls for setting the desired temperature and flow power. There will also be a hall flow meter and a LCD. I have read on the topic of PID controlling and I am eager to try it.

There are couple of unknowns for me.

  1. I will have to put a temperature sensor in the pipes. I don't know anything of pipes and water works. Of course everything will be tested properly on the bench before I'm going to ruin the actual shower :slight_smile: The question is can I waterproof the sensor with hot glue? Or should I use only bathroom-grade silicon?

  2. Most of the solenoid valves I've seen have two states - open and closed, but I will need a flow control. Like 10% open or 50% open. I've read this can be accomplished with PWMing the valve. Is any valve suitable for this? Won't PWM drastically reduce the valve lifespan?

  3. Housing for the mcu, display and wiring. I suppose any IP66-rated case will do the work? I am concerned of condense within the box.

  4. Water resistant potentiometers for defining the temperature and desired flow. I have not seen any in the shops. Can you direct me to something? I think I'm getting the search terms wrong.

Hello ...
Why not a thermostatic mixer ?

Solénoïde valves will not works with a high frequency PWM ... and you will get a pulsed shower !
You can find motorized three way valves (2 inputs 1 output) ... (Like a thermostatic mixer :roll_eyes: ) which are used in house central heating to mix hot and cool water to have a constant temp at the output

if you are worried about condensation within the enclosure, then you want to conformally coat all of the PWA's (circuit boards) and and electrical connections.

for the temperature sensors, i recommend these:

they are one-wire temperature sensors that are already fully enclosed and water-proof. i have used them in my fish-tank, and in my snakes cage without issues.

you do not want to PWM a solenoid as you will very very quickly kill it. you want to use something like this:

i googled "variable electronic water valve" perhaps you can find something.

i had no issues finding water proof pots online
http://potentiometer.us/potentiometers/singleturn_potentiometer/waterproof.htm

i thought of some additional important details.

how were you planning on getting the temperature sensor to measure the temperature of the water?
the easiest method would be to some how adhere the sensor to the outside of the pipe. another guy did something similar and can be seen in this youtibe video:

if you want the sensor to more closely measure the temperature of the water, that is typically performed by utilizing a “thermowell”
http://en.wikipedia.org/wiki/Thermowell however utilizing one of those in standard household copper plumbing may be rather difficult.

my preference on how to attach the sensors to the pipe can be seen in this image:
http://www.sustainableexperts.com/wp-content/uploads/2011/05/6054232-1024x768.jpg
but i would use zip-ties rather than electrical tape.

additional important details.

I think it's time to read reply #1 again. All this stuff is just a case of re-inventing the wheel, and the end result is an expensive square one.

i saw that, but felt i should also answer the particular questions the OP asked so they had all of the information they need to decide how they wanted to proceed.

Thank you! All of this has been very helpful and insightful.

What is thermostatic mixer? Huh, this is exactly what I am trying to re-invent :slight_smile: I didn't knew that thing existed and it seems like I am re-inventing the wheel... but anyway, I will try to do it. I have never seen those in our hardware stores. We have only static mixers.

I've got a bunch of DS18B20s from ebay for cheap. I am using those in other applications as well, and got them really cheap. $8 for a probe seems kinda too much, so I would try to waterproof them myself. First try with hot glue proved unsuccessful, so next step is bathroom-grade silicon.

Our pipes are copper + plastic. Plastic pipes are used a lot, so I thought I could drill a hole in one of those and stick a sensor inside. Then insulate the hole with hot glue or silicone. Like the thermowell concept. I think it would provide faster thermo response than if you stick the sensor outside the pipe. Plastic pipes are not very good thermal conductor.

you do not want to PWM a solenoid as you will very very quickly kill it. you want to use something like this:
Gemini Valve | Automated Ball Valve Solutions

This was my concern as well. But is this product variable valve? I read it is for on/off applications.

ivanatora:
Plastic pipes are used a lot, so I thought I could drill a hole in one of those and stick a sensor inside.

This is probably not a good idea, and you should definitely ask your dad first. Besides, brass joints and junctions are quite common in poly pipe systems, and would provide a good conductive surface for a DS18B20.

Could you please elaborate why not? Is this about an insulation degradation from contact with water or something like interrupting the water flow in the pipe? My dad is not very good in plumbing, either :slight_smile:

I am still in the research phase, so I will consider getting readings from outside the pipes. It will be interesting experiment to see the differences between the two methods and I might do it.

If you drill a hole in the pipe ... you will certainly have a leakage ... maybe not at the begining ... but it will leak due to the pressure inside the pipe, the temperature variations ... I will certainly never do that !
I attached my temperature sensors outside the pipe, with thermal conductive paste and it works fine !

A thermosatic mixer will be so nice in your shower ! and so safe ! and so reliable ! finely regulated shower ! no electicity consumption while sleeping !

with this, you can change the temperature during your shower without having to reprogramm you arduino with wet fingers !

ivanatora:
Could you please elaborate why not?

If you live in a town, the water pressure can be at least 0.5 megapascal. If you don't know what a megapascal is, which I guess is very likely, ask your mother. If you live on a farm or something, the water pressure may be half that. Even if your supply is just from a tank on the roof, you are probably going to have a leak, I guarantee it, and your dad will be calling the plumber.

B83s:
If you drill a hole in the pipe ... you will certainly have a leakage ... maybe not at the begining ... but it will leak due to the pressure inside the pipe, the temperature variations

I see, that makes sense.

If you don't know what a megapascal is, which I guess is very likely, ask your mother.

I'm getting a bit offended here. What is this "ask your mother/father" thing? Do I act in any way imposing that I am 5 year old?

I’m getting a bit offended here. What is this “ask your mother/father” thing? Do I act in any way imposing that I am 5 year old?

You get that kind of thing here once in a while. Personally, I have no idea what a megapascal is; where I live water pressure is in pounds per square inch. So is tire pressure. We don’t even have meters that will measure that. Megapascal is totally meaningless to me … and my mother.

The way I measured water temperature was to use some of that ‘Rescue Tape’ to tape the sensor to the pipe, then put some pipe insulation (the black cylindrical stuff) over the sensor and pipe. Then, to make sure the critters didn’t destroy it immediately, I wrapped it with some aluminum tape for weather and rodents. It worked really well for about five years before a wood pecker decided to take it apart. I rewrapped it and hope for another five years.

Another method I’ve seen is to use pipe fittings to enlarge a section of the pipe to around 2 inches diameter and thread a hole in the cylinder for a screw in sensor. The screw in type are more expensive though so I took the cheap way out.

Plastic pipes are used a lot, so I thought I could drill a hole in one of those and stick a sensor inside. Then insulate the hole with hot glue or silicone.

Do I act in any way imposing that I am 5

Yes, more or less. Only a child would propose something like this and if you don't check with your parents before you start drilling anything, you will probably be very sorry later. The good advise from B83s in reply #2 will save you grief and money. If you insist on ignoring it, at least take this one to heart, as it is likely to do the same thing.

It was unreasonable of me to assume your mother is au fait with megapascals, but I guess she will still give you the right advice anyway.

A DS18B20 in (rare and expensive) screw fitting or a (common and cheap) stainless probe will be more elegant and convenient, and will probably react faster but, if you lay a bare one against the pipe or metal joint with a little dab of thermal paste, and wrap it in foam insulation, there won't be much difference.

If you are thinking about designing your home, you have to draw a clear image of your dream home. Designing a home that completely match your dream home and full fill all basic requirement is very tough. When you are designing your dream home must think about your bathroom design most of us forget about this but it very important to design. People always look for the options which can make their bathrooms more stylish but they don’t know about the right options. Which toilet , basin, shower are best for their bathroom.

I doubt your db temperature sensors will respond quickly enough for you to control the temperature comfortably. You must have an anti scold device. It does not take must heat to severely burn someone. Virtually all mixers have a thermostatic cartridge to prevent scalding.

I am in the stages of automating the bathroom and am doing a similar thing with the shower.
My idea is to have a shower mixer in a void outside of the shower cubicle.
I will use one stepper motor to turn the on/off valve, on the mixer, on and off.
I will use another stepper motor to control the temperature valve on the mixer, to adjust the temperature for the user.
The switch box in the shower cubicle will have an on/off switch to activate the on/off stepper, and hence turn the water on or off.
There will be + and - switches, so the user can control the temperature stepper, and adjust the temperature of the water, up or down.
There will also be 4 user switches. When a user switch is pressed, the Arduino adjusts the temperature stepper to that users desired temperature. If the user adjusts the temperature, then the Arduino will remember that adjustment for that user.

You must prevent scalding.

Steve