Smart Toilet bi-stable solenoid valve acting strange -what could be the reason and the fix?

[MiniMe4Eng]

I have a smart toilet (Ove Stan) that is built using this valve

Here is the valve manufacturer page but I can't say exactly which one of those is my valve.

http://www.chinazhanying.com/en/products.php?cid=33&tid=32&pid=28&page=1

It is acting strange as described below

I called the toilet manufacturer and they want me to replace the entire assembly
Here are the directions they sent me

Here is how the toilet works: when I flush the toilet there is two valves that open in sequence:
he left one in the above picture is what they call the whirlpool valve which is cleaning the toilet bowl before flushing it.
it basically sends water to make sure that all goes to the bottom of the toilet.
After that this valve closes and a second one situated at the bottom of the toilet opens and it flushes/pushes everything into the drain.

The problem: the wirlpool valve is not working any more not as it used to. In normal conditions it won't open at all anymore.
However by accident I discovered that if I open the sink tap half way that decreases the water pressure in the pipe that supplies both the toilet and the sink and then if I flush the toilet while the water is running everything works relatively normal. Obviously there is a lower pressure at the bottom valve in the toilet but it is still enough to push everything into the drain

I am not sure if the valve is broken or it is that the water pressure is too high and I should try to lower it at the toilet supply end.
That end is controlled by a SharkBite 1/2 x 1/2 Inch MIP Straight Stop Valve, Quarter Turn, Push to Connect Brass Plumbing Fitting but I can definitely put something else there.

I do not trust the manufacturer who is telling me to buy the entire assembly and to replace it.
That generates more profit for them and it seems like a waste to me. Besides that it will be difficult to access the back side of the toilet to remove the assembly, I would practically need to remove the toilet because it is installed too close to the wall.
Based on the valve manufacturer pictures it should be easier to replace just the valve from above.
If based on what you see in the picture (Model F62B08BOL) you know of an equivalent please let me know
The water pressure measured at an outside water tap is shown below. That is located just before the pipe enters that bathroom.
It shows around 90PSI, the valve is rated for 0.8Mpa (116PSI)

Here are the toilet details, I can't find the pressure requirements

https://www.ovedecors.com/en/plumbing/smart-toilets/stan-toilet.html

 

[3DDave]

Replacing the electrical solenoid is only useful if the solenoid is malfunctioning; check to see if the resistance on the one that doesn't work properly is the same as the resistance of the one that does. Then check to see if the voltage being applied is the same amount to both valves. Finally, see if the current is the same by putting a resistor matching the resistance in line with an ammeter to see if the controller board is up to the job.

Edit - it looks like you need a oscilloscope to measure the pulse voltage and pulse current unless your meter has some setting to record peak values.

The part that is the problem is likely to be a rubber part inside the housing. It is also likely that the maker is one that sources the entire assembly from a number of makers so that they have no hope of getting replacements for parts that are internal to the valve and don't want to deal with small parts when the replacement job may be complex.

The pressure is right on the valve - 0.8MPa = 116 upper limit. I see you editted to recognize the pressure.

It could be a small bit of grit that is lodged in the valve.

 

[MiniMe4Eng]

So why is it working if I lower the pressure? Is the voltage/amps/power required to open the valve corelated with the water pressure appliedto the valve?

 

[3DDave]

You say you want to change the electrical part and I suggested testing the electrical part.

I say it is something in the remainder of the valve that is the problem but to find out you need to remove it from the toilet and take it all apart to see. But you don't want to because the installation makes that difficult.

Me, I need to buy a new flapper valve, which is looking to have a ridiculous price of nearly $20, because the current one has stiffened with age so the tank sometimes trickles causing the main valve to top it up an inch of water over 3-5 hours, sometimes. I'm just unmotivated to spend the time at the store getting it. 1st world problems.

 

[gerhardl]

If the valve is working OK by a lower pressure, you can be fairly sure that the problem is not electrical.

Most common for all types of solenoid valves are mechanical problems. Most common is dirt partly plugging bores or lines, hindering movements of plugs, stems or membrans, or also causinng leakage between balancing chambers.

(Please note that all users are protseting on this part, as they all claim to have clean fluid and lines. It is just not true, you will find particles everywhere)

Small rifts in membranes and selings can have similar damping effects, but my guess is dirt.

 

[MiniMe4Eng]

Lowering the pressure solved the problem.
If I bought the entire assembly again it would have been a complete waste as I would have faced the same problem

I have been testing this for the last two days and it all looks good.

Pressure reducing valve details and components used to attach it to the toilet are described here

https://terrylove.com/forums/index....-be-the-reason-and-the-fix.107155/post-763449

 

[3DDave]

Congrats. Since you have not diagnosed why your valves are failing you may have only bought some time with the lower pressure.

I replaced the flapper valve - $8 at the local hardware store; not sure why Amazon had far higher prices. The old one was very stiff and had developed a lime deposit on the contacting surface. It's a surprise it didn't leak worse. I could had soaked it in vinegar or other cleaner and gotten some more life out of it, but the lime would only have deposited into an existing leak path. It took all of 5 minutes.

 

[MiniMe4Eng]

I am being told that the water pressure is higher than it should be for the entire house so it is normal that this valve did not do well when pushed to the limits
If lowering the pressure fixed the problem I don't see why that won't count as a diagnostic.

I am not sure why we are so interested in your flapper valve ...but sure keep us posted.

BTW here is an interesting tool that should make the testing easy

https://www.danfoss.com/en/service-..._solenoid_valve_primary_function#tab-overview