Vaillant Ecotec Exclusive 838 advice please on problem

[Agile]

The fixed fee is only better value when expensive parts are needed and particularly two expensive parts!

For most simple things like F75 faults then a local independent is better value.

Tony

 

[Craigbirk]

Hi, I know this is an old thread but just thought I'd add my bit about my 838. I had same problem with boiler kettling in main heat exchanger on domestic hot water and heating, then coming up with water deficiency. I Initially went straight for the pump which had stopped circulating, causing the water to boil in the main heat exchanger. Changed the pump from the plastic type to metal grundfos type pump (£300). This did not solve the problem. Turned out to be the pcb which I changed. I got lucky this time and found a new one on ebay for £40. This sorted the problem. Pcb lasted a year then went tits up again. Turns out the problem is with the large capacitor on the pcb. Becuase the pump is on and off all the time they don't last long. Bought 2 of the capacitors from rs (£4 each)changed them on new and old board now all works fine. Cheap and easy fix when you know!
If the capacitor is on its way out they can be a bit intermittent. You can some times switch boiler on and if pump doesn't kick in you can flick the capacitor with you finger which will sometimes make the pump go. If this is the case the capacitor is toast. Hope this saves someone all the **** I had to go through!

 

[Agile]

Yes, but as you must be aware a DIYer is not even meant to open the outer cover on that model as it forms the room seal which makes that type of boiler very safe.

In fact your posting could even be construed as contrary to this site's rules that you should not be giving DIY advice on gas related matters!

 

[snes]

Well done, Craig - ignore Tony, I think your findings are invaluable and well worth sharing.

A good bit of detecting. Do the capacitors have a reference or rating on them?

 

[Craigbirk]

Hi the capacitor is 400v 100uf. RS stock number 1802201.
As for Mr (health and safety) Tony. If we are getting technical it's not a gas related matter it's actually an electronic matter. I put this post on here to try and help those people out there who still like to repair things and not have some lazy gas engineer come around and just start changing parts willy nilly.
Nobody fixes anything nowadays. Well I do.
If you're not part of the solution you're part of the problem.
Craig.

 

[Agile]

Craig, you don't seem to understand how the combustion aspects of your boiler work.

The front cover is sealed to enable the boiler to be isolated gas wise from the inside of the house. The potential danger from boilers is breathing the carbon monoxide from the flue gases.

Consequently a DIYer should not be opening the case on that model.

 

[Steelmasons]

Craig, you don't seem to understand how the combustion aspects of your boiler work.

The front cover is sealed to enable the boiler to be isolated gas wise from the inside of the house. The potential danger from boilers is breathing the carbon monoxide from the flue gases.

Consequently a DIYer should not be opening the case on that model.

Most have the electrical grommets missing in any case.