Vaillant ecotec 630 Plus

[Manso]

Installed about 20 months ago, to existing system. Within six months was showing fault F75.
Lots of chat between installing engineer and Vaillant service desk, various adjustments made to no avail. Eventually as customer, I called Vaillant, who send out an engineer who diagnosed "dirt on the sensor". Replaced sensor, system then worked fine.
After one year, serviced by Vaillant.
A few weeks ago started showing F75 fairly regularly, so I called Vaillant again. They sent out engineer who diagnosed dirt on the sensor and (I think) dirt in the pump. Replaced both. He expressed concern that the system might need a powerflush, as otherwise Vaillant might not be happy to continue to come out. (I must say that all three Vaillant engineers were helpful and fixed the problem at the time - the last remark about the powerfush, I am convinced, was to help.)
I had the powerflush done by, so far as I know, an entirely reputable firm, but awoke this morning to F75. Any views, ideas, suggestions?
Thank you

 

[gas4you]

F75 is a very common fault that Ecotec Plus range suffers from.

It can be made worse by dirty system water, but 99% of the time it is down to faulty pressure sensors, which Vaillant know all about but are reluctant to admit to

The pcb is looking for approx 0.2bar pressure increase when the pump cuts in to prove it is working ok.

 

[simond]

Recently, we have had a few of our customers recommended powerflushes by Vaillant 'technicians'.

In all cases this has proved to be a misdiagnosis. But a convenient one for them.

 

[Manso]

To simond

The powerflush has at least removed a possible sticking point for Vaillant in honouring their warranty - though at a price!
However, re your remark about misdiagnosis - what turned out to be the correct diagnosis?


To gas4you

If the answer is indeed a design fault on the sensor - how best to broach such an opinion to Vaillant?

Regards

 

[gas4you]

Don't really know the answer to that as I am fortunate in that my mate is the local agent so looks after me

I can only suggest trying to tell them that you have been reliably informed of their 'problem' and want it sorted.

As your boiler is less than 2 years old, what has happened to your original installer?

I am always there for my customers for the full length of the manufacturers warranty

 

[Manso]

My original installer is happy to help. I think the problem is that when he has phoned in the past, the desk technicians get him to try a number of things, none of which have worked - there seems to be a disconnect between desk and field. The first thing that the Vaillant field engineers go for is quite different - dirt on the sensor - and this has been the problem - when the dirty sensor is replaced, the system then works, usually for several months.
I would be reluctant at this stage to get my installer to replace the sensor, for warranty reasons.
As a Google search confirmed to me, F75 is not an uncommon problem - there is a reference to a duff "orange" rather than the now "black" sensor and further passing reference to a special setting of the sensor which also fixes.
What I will now ask the Vaillant engineer is why they remove the old sensor and replace it with new rather than simply clean it (if that's possible).
{I can imagine that turning the old sensor in is part of the job control system or design/redesign feedback, but nice to know if it can be cleaned}.
I should say that I intend to take out a combined service/ maintenance contract with Vaillant at the end of the current warranty.
Incidentally, I would love to know what your friend the Vaillant agent makes of the F75 problem.

 

[gasgeezer]

There is a f75 kit which replaces the return pipe and has the sensor above the pipe.Vaillant have been using these where pump and sensor replacement have failed

 

[gasgeezer]

Above the pipe should read above the pump.

 

[Manso]

Have i got this right? Your reply should read:-
"There is a F75 kit which replaces the return pipe and has the sensor above the pump."

How does Vaillant become convinced of failure?
Do you know if the field engineers are generally aware of this?
The visit booked for Wednesday will be their third within the warranty period.
Regards

 

[gasgeezer]

Well if they have replaced the sensor and pump ,and have still not cured the fault then i presume this would warrant a kit being used. The engineers should be aware of this remedy as it has been used to cure this fault on several occassions in my area.

 

[gas4you]

Chances are also that you are getting a group service glow worm numpty rather than a proper Vaillant engineer.

Never heared of pressure sensors being cleaned. Only ever being replaced. Get your installer to contact his sales rep and put pressure on him to get it sorted out.

What colour is your sensor?

 

[Manso]

Not sure how I can insist on a "proper" Vaillant engineer, but will try - service desks can be very sensitive on that type of request -any ideas?
The boiler was bought online.
I believe the sensors have been black - not sure about the current one, or, for that matter, where to look on the sensor for black or orange.
Regards.

 

[gas4you]

I believe the sensors have been black - not sure about the current one, or, for that matter, where to look on the sensor for black or orange.
Regards.

Front case off, bottom left at back, pressure sensor is in front of you, about 1" diameter.

 

[Manso]

Thanks.

 

[kingjohn]

I've fixed this fault twice now, just now and about two years ago, by putting a long screwdriver on the casting next to the sensor and giving it a light rap with a hammer. It seems to dislodge the muck (despite having a clean system) that builds up around the sensor.

Hope it lasts another two years. Strangely it was serviced by Vailent last week. Since when the pressure has gone up to the red zone and when I reduced the system pressure today the F75 problem started.