Vaillant ecotec plus 831- F75 followed by F23

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Florrin

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Hi all,
I'm a user of a 831 (it's been fitted in 2010) and started having issues with it recently. I'm not qualified in boiler repair but have done a few days' research and this is what happens with mine:
Started by throwing an F75 now and again but worked fine after a reset. When they became more often I called the gas man who installed it, and he swapped the water pressure sensor. First one he fitted thrown the boiler into F73 straight away so he replaced (the replacement) sensor with another new one - no errors with this one, quickly checked boiler operation - just turned a tap on for 1 minute, had hot water coming out and left. I thought it's all good until I tried taking a shower and noticed hot water was coming out freezing cold then hot for a few seconds then cold for a minute and so on alternating. Boiler seems to work fine on CH but didn't have to use it due to outdoor temp at the moment. Now it throws F23 errors which you can reset but still have the alternating DHW temp issue.

Based on previous posts by Agile and Bunnyman I've gathered some more data hopefully will help - codes below:
d.22 = 1 when hot tap is on
d.36 = returns value according to flow rate
codes I found odd:
d.40= 40 - 46 centigrade
d.41= 61 - 65 centigrade
How can the return temp be higher than flow? is this normal?

When boiler produces hot DHW is showing S.14 but goes into S.98 after 20 seconds of producing hot water and burner stops although hot tap is still running.

I don't think my model of 831 has the canoe plastic filter that other ones have next to the water pressure sensor as couldn't see one myself or the gas man. The old sensor he pulled out had some fine black bits coming out if it.

Diverter valve has been swaped last year as was leaking really bad and now have the newer ones with the adapter fitted - DV seems fine, no leaks now.

Could someone please help with a suggestion as my gas man is puzzled, has no idea of what's wrong with the boiler - he has rung Vaillant and waiting for advice but it's been a long wait already - 3 days.

I live in Milton Keynes and would appreciate if any of the Vaillant experts (I know one lives in Northampton) would be able to book me in for a repair.

Many thanks,
 
At a guess Id say the gas man doing the repairs is not really a gas man.
Although an easy boiler to diagnose and repair an average engineer would be able to sort it,
The error 75 73 and 23 message is common on this boiler and indicates low pressure/flow and R sensor/ pressure sensor or pump.
I would also guess who ever attempted to do the repair may have made matters worse.
But you really need a proper gas man to do the work.
 
Thanks @easyflow
How is it possible that return temp measured by d.41 is higher than flow temp d.40? Is it possible that my 'gas man' could've inversed the flow / return NTC wiring, although I don't think there was a need for him to detach these when replacing water flow sensor? I've read somewhere this could trigger a F23
 
out of interest , who actually fitted the boiler ? you need a different engineer
 
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The obvious expectation is that the connectors have been swapped over but that needs a gas reg person to check.

On your boiler the front cover forms the seal which makes the boiler room sealed and endures the boiler's safety. It should not be opened by a DIYer.

We have a closed section on this forum where gas reg engineers can discuss and obtain advice on any problems.

The expection is that any engineer would access this area for help. But it seems yours is not interested in doing any more than calling Vaillant.

Tony
 
I must be better at this comedy writing than I thought.

At the classes I feel that its far more difficult that doing the ACS gas assessments!


But more confident for my Monday class as somebody told me two jokes last night at a party.

Just in case though I bought a Billy Connelly DVD today at a car boot. But then dropped my phone and the criminal who picked it up answered a call to it but did not speak! Lost a lot of numbers there, so not many dates for the next week!
 
Agile said:
The expection is that any engineer would access this area for help. But it seems yours is not interested in doing any more than calling Vaillant.

Tony
Click to expand...
Do you really feel that every RGI in the UK is familiar with DIYnot combustion chamber?...you're more delusioned than I thought...
Ask 100,000 RGI's in the UK if their familiar with this forum and I guarantee you'll get a blank stare..
 
Any RGI who is having a problem doing a repair should make every effort to get help, one of the best ways now is to use the internet.

It does not take many searches to get a link to this forum.

Google "Help to fix F75 Vaillant fault" and this forum comes up on the second page after all the paid for listings for British Gas and probably the web blitzed Ben Gas Man.
 
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Agile said:
Any RGI who is having a problem doing a repair should make every effort to get help, one of the best ways now is to use the internet.

It does not take many searches to get a link to this forum.
Click to expand...
:rolleyes:
 
Thank you all for your comments - I have a working boiler now, which I managed to fix myself :)

The issue was flow NTC being pushed down on the bent section of flow pipe by gas man, in order to make enough room to access and replace water flow sensor next to it on return pipe, so it was reading considerably less than actual temp, hence flow temp was lower than return. I only had to rotate and push the sensor up just under an inch and it started reading correct temp and boiler is working fine.

@AGAS engineer fitting the boiler is old school, probably best suited repairing older boilers that don't use so many sensors and computer logic - in all fairness he was ok fitting the boiler in 2010 and replacing a leaking DV last year

@Agile you're right, I shouldn't have removed the front cover on boiler but considering it was a simple pull up required as didn't have any screws keeping it in place, I thought I'll have a look without tinkering with it, especially that my gas man was hopeless and most people suggested blocked secondary HE, which I felt it wasn't likely to be the case, as my boiler worked fine before / in between the F75 incidents. Front cover is back on now :)

This forum has been an invaluable resource to me, I've learned a lot about combi boilers in the past week - I'm deeply grateful to all experts posting advice - it helped me diagnose / track the issue back to NTC's

Many thanks again,

Florin
 
Florrin said:
I shouldn't have removed the front cover on boiler but considering it was a simple pull up required as didn't have any screws keeping it in place,
Click to expand...
"Pull up" or pull forward?...so no fixing screw holding front cover in place along with no clips?

Another troll...
 
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