Am I doing something wrong?

[Peterphuket]

A technical problem with a water boiler, normally used for the shower but now used as a tool in the kitchen under the sink.
Ordered a Toshiba 3800W model from Lazada and fitted it in the kitchen cupboard, everything connected correctly including ‘earth’
Initially it worked properly, also tried the test and reset button, that too worked properly, up to and including hot water.
But after a short while, nothing, the blue power light was off and only the LED concerns ELCB was on.
Power disconnected, waited a while and reconnected, but nothing.
Waited a day, plugged in and yes it worked again, again for a while.
In the box and back to Lazada.
The same day I went to Watsadu and bought a similar Toshiba water heater, again everything seemed fine until the next day (today) when the same phenomenon occurred again.
Is anyone familiar with this extremely strange phenomenon?
Your help is greatly appreciated.

 

[Lacessit]

If it has happened twice on the same model, I would suspect a design fault.

[Peterphuket]

3 minutes ago, Lacessit said:

If it has happened twice on the same model, I would suspect a design fault.

Yes that makes sense, but Toshiba, and purchased from different companies, so perhaps a different batch, you wouldn't expect that, would you?
That's why I'm still looking for the fault mainly in myself.

[CharlieH]

Just a thought, that unit is a shower unit, designed to be in an open room, not in an airflow-restricted cupboard.

 

Overheating or Thermal Cut-off Activation

Water heaters, especially compact models like yours, have thermal cut-off mechanisms to prevent overheating.

• Symptoms: They work initially, then shut down after heating due to overheating or poor heat dissipation.
• Solution: Ensure the unit has adequate ventilation in the cupboard. Compact spaces can trap heat, causing the safety features to kick in.

 

 

[JAS21]

Is that model for a single shower unit or multi system … if it’s for a shower where  you open a valve to give it pressure to start it won’t like having pressure all the time and no flow.

 

I think that the answer is in the first two lines of your topic ……

[Peterphuket]

25 minutes ago, CharlieH said:

Just a thought, that unit is a shower unit, designed to be in an open room, not in an airflow-restricted cupboard.

 

Overheating or Thermal Cut-off Activation

Water heaters, especially compact models like yours, have thermal cut-off mechanisms to prevent overheating.

• Symptoms: They work initially, then shut down after heating due to overheating or poor heat dissipation.
• Solution: Ensure the unit has adequate ventilation in the cupboard. Compact spaces can trap heat, causing the safety features to kick in.

 

 

Worth a try, will open the cabinet door and add a fan.

[Peterphuket]

16 minutes ago, JAS21 said:

Is that model for a single shower unit or multi system … if it’s for a shower where  you open a valve to give it pressure to start it won’t like having pressure all the time and no flow.

 

I think that the answer is in the first two lines of your topic ……

It is a simple boiler so yes for a single shower, and yes there is constant water pressure on it, isn't that good then?

[JAS21]

54 minutes ago, Peterphuket said:

It is a simple boiler so yes for a single shower, and yes there is constant water pressure on it, isn't that good then?

You need one that is operated by a flow switch … think it’s called a multi point. 
 

Well if it’s designed to operate when it’s gets pressure, then the pressure will initiate the heater … then the unit will trip on high temp ….then it will reset. …then it will ……….      Seems logical that will happen until the unit is ######

[Peterphuket]

52 minutes ago, JAS21 said:

You need one that is operated by a flow switch … think it’s called a multi point. 
 

Well if it’s designed to operate when it’s gets pressure, then the pressure will initiate the heater … then the unit will trip on high temp ….then it will reset. …then it will ……….      Seems logical that will happen until the unit is ######

If I look to the schematic it seems like it have a flow switch....

[Peterphuket]

Just now, Peterphuket said:

If I look to the schematic it seems like it have a flow switch....

But very strange, it is now switchched on for more than 3 hours, I use a few times warm water and it still look like okay.

[Yellowtail]

12 minutes ago, Peterphuket said:

But very strange, it is now switchched on for more than 3 hours, I use a few times warm water and it still look like okay.

I'm with JAS21. I do not believe the shower units are designed for constant pressure. 

 

 

 

 

[Peterphuket]

5 minutes ago, Yellowtail said:

I'm JAS21. I do not the shower units are designed for constant pressure. 

 

 

 

 

Sorry, I don't understand  'I'm JAS21'

[Yellowtail]

2 minutes ago, Peterphuket said:

Sorry, I don't understand  'I'm JAS21'

 

Sorry, I meant to say was: I'm with JAS21, I do not believe the shower units are designed for constant pressure.

 

The shower heaters are designed to have the water shut off before the heater. 

 

The water heaters (what you want for your sink) are designed to have the water shut off after the heater. 

[JAS21]

Yes .. that does have a flow switch ..there is loads on the internet about flow and pressure switches on shower heaters … there is also this 2014 topic which may be of interest to you

 

 

 

[Peterphuket]

8 minutes ago, JAS21 said:

Yes .. that does have a flow switch ..there is loads on the internet about flow and pressure switches on shower heaters … there is also this 2014 topic which may be of interest to you

 

 

 

Thank you, but I am not convinced, when I enter ‘hot water heater for under the kitchen sink’ on Google, I get the same boilers as the one I have now. Very confusing all round.

[Fruit Trader]

The answer might be in the difference between vented and unvented tankless heaters explained by @Crossy in the thread below.

 

 

 

[Yellowtail]

In the OP you implied you have a shower heater. If you actually have a water heater, it should work fine. 

 

Water Heaters & Boilers for bathroom | HomePro Online 

[ravip]

 

This seems to have automatic water pressure sensing and a ground inspection system. 

Did you check what it's minimum requirements are?

 

Just a thought...

Failing all, email Thoshiba Thailand. Most times these companies are helpful, I have experienced.

 

 

[Peterphuket]

3 hours ago, ravip said:

 

This seems to have automatic water pressure sensing and a ground inspection system. 

Did you check what it's minimum requirements are?

 

Just a thought...

Failing all, email Thoshiba Thailand. Most times these companies are helpful, I have experienced.

 

 

 

[Peterphuket]

@Ravip

That's a good idea and I honestly hadn't thought of that but have since sent an email to Toshiba, so a matter of waiting and seeing.
Thanks for the advice.

[apples11]

I dont know about the Toshiba model but many water heaters have a cut off switch inside to prevent over heating normally located on top of the copper heater unit. A small button that you press to reset.  Is your tap a single hot and cold mixer tap, if it is you can only use it on full hot or full cold. If you try to mix hot and cold to get the right temperature you reduce the flow of hot from the heater and it will over heat and cut out.

[rwill]

16 hours ago, Yellowtail said:

I'm with JAS21. I do not believe the shower units are designed for constant pressure. 

 

 

 

 

All my shower units have pressure on them all of the time with no problem.  The valve used to turn the shower on and off is after the water heater.  

[Peterphuket]

OK, thanks all for your advice, end result is ‘it doesn't work’ so today I am going to remove the boiler and return it to the supplier.
Just wondering apart from Stiebel Elton, which I think is too expensive, what options I have left.

[ignore it]

Stop showering under the sink!

[Carlos Primeros]

My Stiebel Eltron 12 kw heater is working since 21 years without problems...

Sometimes it pays to go for the more expensive things...

[ravip]

1 hour ago, Carlos Primeros said:

My Stiebel Eltron 12 kw heater is working since 21 years without problems...

Sometimes it pays to go for the more expensive things...

Agree. Our Stiebel Eltron has also been working for over 15 years.

Having said that, one thing to keep in mind is that new products are not made to last a long time IMHO.

[Peterphuket]

2 hours ago, ignore it said:

Stop showering under the sink!

I can't ignore you with this joke😂

 

By the way, I've just returned the boiler to Watsada, but it wasn't as easy as it was with the mail order companies, first they wouldn't accept it under the pretext of what exactly is broken... the appliance just doesn't work... 'yes, but did you have water connected to it'... hu?
After about 10 signatures on a copy of my driving licence, I got my money back with great difficulty.
I will do it differently next time.

[sometimewoodworker]

13 hours ago, Peterphuket said:

Just wondering apart from Stiebel Elton, which I think is too expensive, what options I have left

In my experience you either buy cheap and need to replace it again and again and again, or you buy expensive and it will often just keep on going almost forever. I learned this lesson over 60 years ago. I have very occasionally bought cheap and it has almost always been more expensive than buying quality, or it was for very short term usage.

 

so if you are going for cheap then something like this, from AliExpress 10L stored water heater, will be good enough (maybe) it certainly should be cheap enough!

[Peterphuket]

11 hours ago, sometimewoodworker said:

In my experience you either buy cheap and need to replace it again and again and again, or you buy expensive and it will often just keep on going almost forever. I learned this lesson over 60 years ago. I have very occasionally bought cheap and it has almost always been more expensive than buying quality, or it was for very short term usage.

 

so if you are going for cheap then something like this, from AliExpress 10L stored water heater, will be good enough (maybe) it certainly should be cheap enough!

Of course, I agree what you say, have the same over 60 years of experience, but still managed to find a cheap one at Lazada yesterday, even cheaper, it is not used much so I take the risk.

Anyway, thanks for the advice.

[Crossy]

4 hours ago, Peterphuket said:

Of course, I agree what you say, have the same over 60 years of experience, but still managed to find a cheap one at Lazada yesterday, even cheaper, it is not used much so I take the risk.

Anyway, thanks for the advice.

 

Do you have a link for that heater?

 

It looks like it might be suitable for a kitchen sink installation for which I need one.