One of the stupid things has always occupied my mind,is that crazy water tap stuffs in bathrooms,kitchens,restrooms,etc
it always takes significant time and wasted water to adjust proper water temeprature and flow via tap's lever,
so ,I wondered to make some low cost thing by servo motors,arduino and 3d printer to adjust tap's lever automatically or maybe even be voice controlled for the next phase .
it must be like a 2 axis servo joint with 3d printed mounts and proper torque to move a usual tap lever.
it's appreciated to know if someone has had any experience about the subject,like min servo torque ,mechanical design and so on.

 

Different washing techniques, variable required flow rates and people's temperature preferences mean that there is no one-size-fits-all setting, so any electronic control will require user inputs which could change rapidly. How do you propose to handle that?
Personally, I think that servo control would be more complex than simply operating the tap manually .

 

If you are going to do all of this modification to add automation, get rid of the single-lever tap altogether and go with two electrically controlled valves, one for hot and one for cold.

You have two degrees of freedom (two independent adjustments you can make) and two parameters you want to control (flow rate and temperature). The flow rate is the common-mode signal to the valves and the temperature is the differential-mode signal to them.

The tricky things to take into account are the two temperature-related time delays. It takes a while for a change in the valve settings to result in a change in temperature at the faucet output and it takes a while for a change in temperature at the faucet outlet to result in a change in the temperature reading that your controller is responding to. The first one is also not consistent. At first there is a signficiant time delay as the hot (and to lesser degree cold) make their way through the pipes to the faucet. Then there is a smaller delay after that as the pipes are brought to thermal equilibrium with the water, and finally there is a very small residual delay once everything settles down. If you don't take this into consideration, you can end up with scalding water when changes are made.

 

Go to your water heater and adjust the temperature or the power until you get the temperature you like at a tap setting you can get with the flick of a wrist.

In the case of an on-demand water heater an ordinary lamp dimmer circuit can be used to control power used to heat the water (this setting may need a summer/winter setting depending upon where you live).

 

The Aqualisa thermo control valve works brilliantly but it's expensive - uses a bimetal strip which reacts really fast to changing water temperature. Maybe there is a way you could incorporate something similar in a control valve. I'm sure they have a patent on it.

 

Personally, I think that servo control would be more complex than simply operating the tap manually .

I agree it's not quite simple. They do have smart faucets which look pretty cool where I can tell my faucet to dispense measured amounts of water hands-free but getting to and maintaining a temperature can be a challenge.

In the case of an on-demand water heater an ordinary lamp dimmer circuit can be used to control power used to heat the water (this setting may need a summer/winter setting depending upon where you live).

My sister loves the On Demand water heaters. She has a laid out cabin in West Virginia that uses On Demand. My first look at on demand was early 70s in Japan where hot water is electrically heated and electricity is expensive. Nice because your hot water source is a few feet if that away. Here in our home my hot water tank and heater is in the basement so when I want hot water I open the valve and wait, and wait, and wait... the water flow slowly comes up to temperature and then using hot and cold metering you get about what you want. Good thing water is not too expensive.

They do make 3 way motorized ball valves that can use a 4 to 20 mA input provided by a proportional temperature controller. I used one in a project once. First problem was line pressures changing so went rate of flow so went problems. Pressure regulators came next. Eventually we nailed it but it was a costly project.

Even on many of the fancy home automation faucets temperature regulation is left to the user. Today's word... Expensive.

Ron

 

Never used that smart faucets,but I guess there must be more issues than their higher price,
Dealing with hard water and calcification that ruins mechanical parts and risk of non repairability would be mentioned as one.
For living in flat and aprtment with limited space,any changes in infrastucture as on-demand heaters would be pain so.
BTW that the subject is actually a Thingiverse or Yeggie challange for opensource low budget guys than talking about luxury product sales.

 

Having used an on-demand propane powered shower, what I like is that the temperature is preset with the valves on the heater. This helps conserve water (and heat) since I can turn the flow on and off at the shower head without having to readjust the hot and cold mix each time. Maybe that arrangement would be allowed for normal bathroom plumbing if there were check valves to prevent water going the wrong way.