Vaillant EcoTec937 hot water cool after 10min...design flaw?

Maybe, but the last time I called out an engineer it ended up taken 2 guys a week not to fix it. I will fix it myself and to look on the bright side I will have a pile of spares for any future problems. Having had a valiant to about 25 years Im sure I will get more failures and use up the parts. As for not diagnosing the problem, your correct I haven't diagnosed the problem but I could not see inside the heat exchanger and it was a very posable cause giving the symptoms. It was Vaillant that could not provide any further recommended diagnostics and they recommended to change the control board then pump based on the pump being more expensive. if you take a look at the manual it does not provide for any instruction on how to diagnose problems with the cylinder storage side nor do they attempt to describe how it functions.
 
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So you expect the boiler manual to give easy to understand DIY fix information?

Might as well get rid of doctors and do your own DIY medics as well.

Most would think that a boiler engineer would be the one to do the diagnosis.

Tony
 
Hi Tony,
All the engineers that I know also use the manuals provided from Boiler manufactures, I don't think its asking too much for the manual to have enough information to diagnose problems. Generally speaking the Valliant manuals are very good.

The last time I looked you had to be pretty clever and study a long time to be a doctor.

Most can follow some simple instructions safely and do some DIY and save their hard earned money for other things such as paying the gas bill or buying food.
 
Exactly!

It always surprises me when DIYers expect that they can do better at repairs than those who work on boilers every day.

Quite apart from the extra cost of buying parts which are not needed or were carelessly damaged by water.

Tony
 
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Well I'm getting old and the dog was barking and I forgot to shunt in both the supply and retune lines. I'm sure it never happens to the experts.

Anyway I love DIY its better than watching East Enders on TV.

Any bright ideas if its not the pump, cant be much left to change out?
 
Its not a matter of "changing out" !

Its a matter of diagnosing what the fault is and rectifying it.

Bit like solving a murder mystery! You look at the clues! That's why I find it so fascinating.

Tony
 
Please take a look Ecotec 937 storage control PCB, charge pump sensor and see if you can solve the mystery of how to test out these parts. The boiler looks like its running ok with the flame on when you draw water 9Lpm shown on the boiler and it looks about write. So I think the flow sensor is working (I still might change it). the boiler has the C flashing when drawing (even with the comfort mode switched off), no Idea if this is correct. S.24 is the code showing when operating. Temperature showing on the from is around 60 but the water is cold. The charge pump is going on and off. Valliant sat it should ne on when drawing water. Usually you can shut the water off and on again and it corrects itself. The diverter valve is sitting in the hot water mode.
 
D

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