Vaillant F75 pressure sensor errors

[spile]

Pressure sensor needs replacement again after three F75 faults in a month. All cleared by using the ignition button but I’m getting to the stage where I may be simply replacing my pre-2010 Ecotec. A poor 10 year history of reliability - four pressure sensors, a heat exchanger, o rings and diverted valves. I’m on first name terms with the engineer . I understand newer Vaillants are more reliable but my experience with the Ecotec had put me off. Worcester Bosch?

 

[CountryFan]

Are you sure it’s the pressure sensor? IME if it’s the sensor, then it’s down to a dirty system. We have literally hundreds of these boilers on our patch in social housing, some have the sensor replaced often, others have had the original orange one. Whenever I changed one I look to see how blocked it is, and they’re usually full. You can’t go blaming the boiler for doing it’s job if the system is dirty.

 

[spile]

Yes based on previous experience. System is clean with inhibitor and magnatec that is cleaned regularly but has very little particulates. We do have hard water that is known to cause F75 sensor faults. Later models sorted the issue out.

 

[spile]

Are you sure it’s the pressure sensor? IME if it’s the sensor, then it’s down to a dirty system. We have literally hundreds of these boilers on our patch in social housing, some have the sensor replaced often, others have had the original orange one. Whenever I changed one I look to see how blocked it is, and they’re usually full. You can’t go blaming the boiler for doing it’s job if the system is dirty.

All sorted but I am going to get the system flushed. Do you recommend a power flush or flushing with Sentinel X800?

 

[CountryFan]

All sorted but I am going to get the system flushed. Do you recommend a power flush or flushing with Sentinel X800?

X800 is what we use, but I've been told on here by engineers far superior than me that is an aggressive cleaner, so maybe err on the side of caution and go for power flush

 

[spile]

My engineer can do a regular flush with X800 over two days but I’d need a specialist to do a power flush that’s going to cost £400 upwards. Hence asking here.

 

[DP]

X800 is what we use, but I've been told on here by engineers far superior than me that is an aggressive cleaner, so maybe err on the side of caution and go for power flush

I would have no hesitation of using x800. BUT, big but, system post cleaning has to be flushed totally
Power flush. It will only clear, subject to person carrying out the flush being knowledgeable, the muck from the bottom rib of the radiator.

A drain down is not a flush. Connecting a power flusher and not agitating the base rib is not a power flush. Regardless anything above the base rib (through which flushing water flows), remains dirty. Either way will easily take about a day to carry out the job properly.

This post has so many inconsistencies. I have the same boiler. System has not been flushed, nor inhibited. I do get F75 now and again, have had to replace occasional sensor but mostly it not a sensor issue. Have replaced a PCB, pump and diverter too but then the boiler is older than OP’s boiler. And finally, it gets looked at when it breaks down and does get a service on own boiler that other RGIs do to thier own boiler nudge nudge. I think issue is the engineer carrying out the task. If the system was that dirty, I would forget the cleaning but install an Addey magnetic filter, preferably the bigger one.

 

[DP]

My engineer can do a regular flush with X800 over two days but I’d need a specialist to do a power flush that’s going to cost £400 upwards. Hence asking here.

What is a regular flush. What is your engineer proposing

 

[DP]

OP, above is a serious question.
With so many would be 'professions" out there calling themselves doctors and what not, if you do not respond, how are you going to resolve the issue.

 

[spile]

1. I would have no hesitation of using x800. BUT, big but, system post cleaning has to be flushed totally

Yes get that

2. Power flush. It will only clear, subject to person carrying out the flush being knowledgeable, the muck from the bottom rib of the radiator.

Yes get that

3. A drain down is not a flush. Connecting a power flusher and not agitating the base rib is not a power flush. Regardless anything above the base rib (through which flushing water flows), remains dirty. Either way will easily take about a day to carry out the job properly.

Yes get that

4. This post has so many inconsistencies. I have the same boiler. System has not been flushed, nor inhibited. I do get F75 now and again, have had to replace occasional sensor but mostly it not a sensor issue. Have replaced a PCB, pump and diverter too but then the boiler is older than OP’s boiler. And finally, it gets looked at when it breaks down and does get a service on own boiler that other RGIs do to thier own boiler nudge nudge. I think issue is the engineer carrying out the task. If the system was that dirty,

Happy to address the inconsistencies if you tell me what they are. My engineer is trusted and given me good advice. My options are power flush (he can’t do) or chemical flush (which he can do).

I would forget the cleaning but install an Addey magnetic filter, preferably the bigger one.

Given there is already a magnetic filter in the system and that it’s working but clearly not picking up everything then I would have expected you to recommend a chemical clean which in fact what you said above when you said you had no hesitation in using X800.