Potterton Suprema 40

[leshay]

Hi (and a Happy New Year)

Just joined the forum.

After reading lots and lots on the forum trying to tie down a fault on the above boiler, I have tried the following.

History:
New house with above about 8 years ago.

I don't know a technical term, but the system has 1 tank for both CH and HW

New PCB installed by BG about 1 1/2 years ago, from a maintenance contract.

Called BG out 3 times since then as boiler shut down prematurely and try to restart several times but failing, or wouldn't start (continuous green every second or so), or try to start fires up but shut down immediately.

Anyway BG,on each occasion changed the overheat sensor and seemed to fix problem for a while.

Cancelled BG contract as it seems they can't fix the problem. Last thing they did on request was to leave with a new sensor fitted.

OK, so the problem has returned. Same symptoms as above. I can switch off/on for a while until it stays fired up for a while, but unless I stand over it, the CH starts to run cool/cold and HW same. Usually find boiler green light flashing every second or so, or trying to restart and failing with green light flashing every second. No red light seen at all - ever.

From the info gleaned here, I have tried a simple test. I removed the cover, removed the overheat sensor (still connected electrically) and let it cool down and let it hang free. Restarted system (still with cover off) and everything works a dream.

So, unless I am missing something, simply replacing the sensor (again!) should get the system back up and usable,

However, why should my system eat through these sensors? (BG say they rarely had to change them)

I know about the safety infringements, but at the moment, until I can get the issue fixed I will need to run without the cover/sensor (under supervision of course)

I have tried finding a source for the sensor (it is just a small plastic cap with a tiny blob at the end of the 2 wires poked into a hole in the pipe fitting(loosely).

Would anyone here be able to point to a source, or part number or any other help info appreciated.

The cost must be minimal as the part looks so tiny and flimsy - can't be much in the making of them.

 

[45yearsagasman]

What an idiotic thing to do,running it with the cover removed! What advice do you expect to get on here? You know what to do.

 

[leshay]

Well thanks for that, very revealing.

I am not an idiot! Of the two of us, there is only one idiot.

 

[powell30]

Breaching the combustion chamber is illegal and dangerous......that constitutes stupid to me.

As for you removing the overheat sensor.....that is a system safety device and if a gsr did that and left it so it would be riddor reportable! Regardless of the fact you were testing it it's stupid!!

That said if your o/h stat keeps tripping look elsewhere on the system for faults.....pump, sludge, blockages.....

Or get someone who knows what they are doing!!! you don't

 

[Gasop]

It would be best that you call back BG again.

Your description of the component you are fiddling
with is not the overheat thermostat!

 

[Agile]

Well thanks for that, very revealing.

I am not an idiot! Of the two of us, there is only one idiot.

It may be better if the readers make that judgement!

For a start, the component you describe is the NTC heat sensor!

For the middle, it should not be loose in its housing. It should be packed with thermal transfer paste!

To end, you are so (over) confident that you can "safely" disconnect what you thought was the overheat stat! But has it ever occured to you that you dont actually KNOW what temperature your boiler actually reaches ? Have you ever considered that it might be reaching an over heat temperature?

An ex trainee had a very similar problem with that model and called me for help. Until he had under my instruction replaced something mentioned above, he was very sceptical about my suggestion! But he called back later to confirm that it had solved the problem at a cost of about 30p.

Whilst you seem to believe that those who repair boilers are "plumbers" and by definition they must be thick as they all left school at 16 with three or fewer GCSEs, could it be that at least a few actually know more about boilers than you do?

And for the sake of safety you should not be opening the combustion chamber!

Tony

 

[Andygasman2010]

I will need to run without the cover/sensor (under supervision of course)

Under supervision??? What exactly will you be waiting for, CO poisoning???

You need to pay someone who knows what they're doing. BG would have fixed it eventually. You could even go back to them for a fixed price repair, it sounds likely that the boiler isn't even at fault.

This site is for DIY advice only and i'm affraid what you're doing is beyond the scope of DIY.

Do not run the appliance with the case off.