Alfa-mix or obiwash DIY alternative using home assistant for washing machines


As you probably know, a washing machine usually needs warm/hot water only during one cycle, the rest of the time it can use cold water.

Standard washing machine have only one inlet and they need to heat the water via a resistance, while more expensive models have a cold and a warm water inlet.

Since heating the water is very energy consuming (especially if you need to heat it to 60 degrees from like 6 degrees in cold months), if you have a way to produce warm water in an more efficient way (i.e. solar, heat pump, etc.) you would spare of lot energy.

But there are few machines in the market with double inlets, and they are like 2 or 3 times more expensives than an equivalent single inlet machine.

For this reason, there are some “semi-smart” tools like alfa-mix or obiwash that try to replicate the behaviour of a washing machine with 2 inlets and and internal mixing valve in a crude fashion based on a timer.

For the simplest case of absence of pre-washing, the devices would provide warm water at a temperature configured manually on them, hopefully not warmer of the program of the washing machine, and they would provide warm water for 10-15 mins from the start.

After they would switch to cold water.

So if all goes well, the washing machine would get the pre-heated water at the target temperature for the washing cycle, and would get the cold water for the other cycles, with a significant energy saving.

Now, the devices per se are relatively expensive, not so much of course to compare to a machine with the dual inlet, but their use poses many operational issues.

At least one of them can start autonomously when the washing machine starts (i.e. when an automation has detected there is enough solar energy production to start a wash), but it is necessary to have configured correctly the water temperature (lower than target is fine, higher is big no-no), it could be an hit or miss if for whatever reason the machine is stopped or the timing is off, etc. etc.

One compromise could consist (if one never washes cold but 30 minimum) in using a simple mixing valve permanently providing the washing machine a constant temperature that can be adjusted in winter and summer to an appropriate value.

Now, if the washing machine was a connected one, and it was possible to start it remotely and for example monitor what program is selected and read which is the target temperature and which cycle is taking place, I was thinking it could be possible to have HA step into the picture.

Ideally, an off the shelves, commercially available motorized TMV valve compatible with HA would exist, but I did not find any at a first glance.

The easiest alternative would be to have one of those cold start water faucets controlled by a zigbee 1/4 valve controller, if this could be controlled to partially open with some calibration curve to have an approximate temperature mapping between position and water temperature.

Or one could make a T connection and put 2 HA controlled motorized ball valves with anti return valves and try again to calibrate the system.

The question is, by any chance is there someone that is already doing something similar and is willing to share the implementation?

Do you know of a motorized TMV valve that is easy to operate and acquire?


Someone seems to have managed something similar with jeedom. Copy pasting the relevant part here in case the source URL goes dark:


Alors j’ai pris la V3V Wipex : … 75199a.htm

Ainsi que le Servomoteur STM pour cette vanne: … 75225a.htm

Le temps de rotation du servomoteur est de 120 secondes pour basculer d’une position à une autre, du coup avec les scénarios qui vont bien, je peux calculer et piloter une ouverture partielle.

Pour le pilotage du servomoteur, j’ai donc un Wemos avec plusieurs Relais (2 seront nécessaires pour piloter 1 servo), comme expliqué dans le tuto de sarakha63 (lien dans mon précédent message).