Potterton Profile problem

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A neighbour of mine (female) has a 10 year old PP, it's having spells where the ignition sparks every second and you can see the flame size cycling up and down at the same time. From a thread in 2001 it could be a break in the spark lead. However their local corgi guy is talking about a failed gas valve but apparently he doesn't really inspire confidence. If it were mine I would have a play, but I can see this repair getting expensive, say if the guy replaces the valve and then the board. My gut feel is that if they can't do a "cheap" fix she should consider a replacement boiler. Or am I being unfair to Potterton?
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I'd be bl**dy wary about mending Gas appliances for neighbours. Wont you be at risk of "it was OK and didn't do something else wrong before you touched it" and all that sorta stuff?. Apart from if anything should go wrong otherwise.
Apart from the fabled Potterton electronics:-(...
--
Tony Sayer


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By "flame size going up and down", do you mean that it's variable, or that the main gas is coming on and going off again?
I can't remember if the main valve is a two stage one, but it is switched by a relay on the pcb, either on or off.
If it starts sparking while it's in normal running mode, the pcb should be switching the main valve off.
Loss of flame sensing can be caused by a) a faulty pcb b) a break in the HT lead c) bad earthing d) the electrode not being in the pilot flame (e.g. the electrode tip breaking up)
--
geoff

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On Sat, 07 Feb 2004 22:16:28 +0000, geoff wrote:

Profiles are tough and generally relaible boilers. It is subseqent models that have got Poxi Batterton into problems.[1] They have a two stage ignition sequence with a double gas valve unit. Firstly the pilot gas vavle is open the sparker sparks the pilot lights (hopefully). Secondly the pilot flame is detected by the one and only PCB. Which turns of the sparker and lights the main gas by opening the main gas valve.
There is no modulation it's either all on or all off.
It is possible that when the main flames come on the flame then moves out of the way of the sensing electrode whic hthen cuts the main gas, the pilot flame then moves back into position and the PCB open the main gas again.
From the sypmtoms described I'd say the gas valve is not even worth thinking about changing the PCB just possibly, a service very much what's needed.
There is only one PCB it does 'everything'.
[1] In fact there are significant numbers of Suprimas being installed in new build. Probably because architects have not clocked the problems with them and are still specifiying them.
--
Ed Sirett - Property maintainer and registered gas fitter.
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One would have hoped that they have eventually sorted the "electronics" problems of this boiler but from what you say this doesn't seem to be the case:-(
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Tony Sayer


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wrote:

That depends on the lifetime cost to the manufacturer of leaving alone vs. doing a design change.
Do you remember the Ford Pinto debacle? This was that if this car was rear ended in a particular way, the doors would jam and the fuel tank would explode, incinerating the occupants.
There were numerous incidents of this and eventually it was noticed by IIRC a consumer action group. It turned out that Ford had known about this for some time but had worked out that it was cheaper to pay out compensation than modify the car.
.andy
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Andy Hall wrote:

What about the Mini? It had an inherent fault in that the fuel filler stuck out from the body and was within a few inches of the rear lights so in the event of a rollover there was a strong probability that fuel could leak and had a source of ignition as well.
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James...
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Another death trap. Fortunately I survived a crash where that happened. A five year old friend of my daughters didn't.
Poxy design:-(
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Andy Hall wrote:

In the case of the Pinto (so wonderfully satired in one of the Naked Gun series of films) it eventually cost Ford dearly when the "smoking gun memo", I think it was known as, an internal document that detailed Ford's decision became public. Courts then awarded massive compensation payments that totally ruined Ford's cost calculations and forced them to actually fix the fault.

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One might have thought that those who spec boilers would have noticed this now. I wouldn't have thought that any self respecting plumber would fir them as replacements!...

Yes, disgusting!......
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Tony Sayer


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wrote:

Well.... the industry is conservative and Potterton continues to live on its earlier good name.
If you've been into a plumbing/heating merchant, there are plenty of manufacturer loyalty schemes with quite nice rewards.

Apologies for raising what must be a difficult subject for you.
.andy
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What does a PCB re-design cost? Pennies, I'd say.
--
*And don't start a sentence with a conjunction *

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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On Sun, 08 Feb 2004 17:06:17 +0000 (GMT), Dave Plowman

.. then the remanufacturing, sparing, quality control, ISO9001, EMC and safety recertification, documentation .....
As a general rule when I did hardware design, it was reckoned that 5% of the task was getting to a first prototype, post engineering such as PCB layout was about another 15% and the rest were the processes to get the thing into production and deal with lifetime issues.
Even a fairly minor component change can be a real headache.
It really is an iceberg.......
.andy
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Well, given that several of these weren't properly done in the first place, and warranty claims must be considerable, I'd say it would be worth it.

Perhaps it's just their priorities are all wrong. I never cease to be amazed by the way makers will pare things down to the absolute minium on a product which has perhaps the most hostile environment for electronics found in the home.
--
*Real men don't waste their hormones growing hair

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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On Mon, 09 Feb 2004 11:07:29 +0000 (GMT), Dave Plowman

Pennies count. It isn't just the electronics either.
There is the urban legend (which I think has some truth) of the days when Plessey made televisions. I once worked with an engineer who had worked in their design department. He would produce a correct design and then the chief engineer would come round with his clippers, look at the circuit diagram and start clipping components out until it stopped working.
Geoff is probably best fixed to commenton boiler electronics, but I suspect that it is the usual sorry tale of inadequately specified components, inappropriate ones for the job and lack of attention to temperature environment as high on the list..
.andy
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Yes they all used to do that:-(
But this was consumer grade product.....

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Perhaps they would be better saved off the MD's perks. then?

I've heard this one many times - but with the company changed to protect the innocent. And when the factory closes due to the dreadful product, and the sales go to overseas, it's put down to the poor British workforce...

Yup. Poor soldering seems common these days though, and not just on boilers.
--
*(over a sketch of the titanic) "The boat sank - get over it

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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On Mon, 09 Feb 2004 18:08:16 +0000 (GMT), Dave Plowman

Well no, because she needs to be rewarded for being the entrepreneur. They miss out the "de pompes funebres" bit.

It comes from the same book as the old one where the little boy is asked what he wants for Christmas and he asks for a cowboy outfit. So his dad bought him (insert your favourite TV manufacturer or parliamentary party,.

.and there's really no excuse for that at all
.andy
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Andy Hall wrote:

There must be a gag here somewhere, let me think, something about cowboy outfits and dogs, ahh got it! CORGI.
--
James...
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What I don't understand about counting pennies is how you can charge about 100 for e.g. a Netaheat or Profile pcb which carries a couple of dozen components
The worst offence which boiler pcb designers commit (IMHO) is the direct switching of reactive loads (fans, gas valves etc) without the use of any kind of snubber to reduce relay contact wear.
The worst offence which I see in the manufacturing process is the really rubbish soldering, especially on Molex connectors
Of course each pcb has it's own weak points, and I have difficulty understanding why these are quite often not addressed when they produce a new issue of that board ... unless of course, no it can't be true, that they don't build them to last - heaven forbid
--
geoff

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