Vaillant thermo compact 615e

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Hi, i am getting f28 code on this boiler, an engineer has already replaced the board and gas valve yesterday. Same code appears.
Called vaillant today and did checks on board for power at gas valve and resistance on connector which was not correct.
He says the gas valve lead should have been changed when pcb was changed as old lead has blown new board. Anyone came across this?
When unplugging gas lead off board there is black scorch marks on connector between the live and neutral which is a tell tale sign i guess.
Cheers
 
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Most experienced engineers will be aware of the gas valve lead problem.

Unfortunate perhaps but I don't think that you should be paying for the unnecessary parts.

Does not sound like a Vaillant engineer as they should all be aware to the potential problem.
 
Thanks guys. It was just another engineer from our company. Will pass info on to him when i complete job, plus i also know for the future.
 
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oh right!

If you are gas reg. you should be posting the closed CC section of this site.
 
Not just a diode but a full wave diode bridge.

You and I both know about them!

Any engineer not aware of them risks an expensive expenditure.

I am sure all Vaillant staff are made fully aware of them. Potty ones too!
 
Thanks again. Fairly new to the forum so wasnt aware of the posting procedure. Will use other section in future
 
Thanks again. Fairly new to the forum so wasnt aware of the posting procedure. Will use other section in future
You need to sign up mate just give them your gas numbers as quick as ,as it may take a while and then you can join the bear pit:ROFLMAO:(y) but we all learn something
 
And sont listen to agile tony, if the mods dont sort him out talking his ****** here
Bunnyman I am not in any way an electronics expert, but I always thought it was a bridge rectifier that was in the lead , whatever that is , Bloody wee **** Mick Shorter telling me porkies :LOL::LOL::LOL:
 
It is a bridge rectifier.

Four diodes in a bridge configuration.


th
 
the MI's say nothing about it so don't listen to agile because most engineers don't know about it

Then the manufacturers are at fault. Agile seems to be better informed.

As to the "bodge" of concealling a bridge rectifier in the lead and "forgetting" to mention it. Beggars believe, but then people who make boilers seem to lack some basic electronic knowledge.

How does the DC coil in the gas valve like being fed raw DC ?
The DC output from a bridge rectifier fed with 50 Hz AC is raw DC, that is DC but pulsed at 100 pulses per second.
Hence the magnetic field in the gas valve solenoid is pulsing at 100 pulses per second. Mechanical inertia of the mechanism seems to prevent the gas valve opening and closing 100 times a second.

If the solenoid in the gas valve is not designed to withstand continuous pulsing by raw DC then the effect of the pulsing on the winding of the coil may be significant and may lead to premature failure of the gas valve solenoid.

That said it might be just a single diode and the gas valve is being fed 50 pulses and 50 gaps per second. Even worse.

This applies to any coil designed to be operated by smooth DC but fed with raw DC.
 
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