What is the problem with modern boiler PCB's?

[matthew4444]

Hello all

I have a Potterton Performa 28 which can't be more than 6 years old at the most. I'm with BG homecare and the boiler has recently had to have a new PCB.

If I dug out my old Sinclair Spectrum (circa 1981) I'm pretty sure it would work without a problem. The printed circuit board consisting of resistors, capacitors, switches, chips etc would not need replacing. In fact on most household items it is extremely rare to have to replace a circuit board. Could someone explain why boilers are any different and that a PCB on my boiler presumably consisting of the same sorts of components as my Spectrum needs to be replaced after such a short period. (Looking through other posts it seems to be a fairly common problem.)

Regards

Matthew

 

[Diyisfun]

Its probably the working environment & that items are made a price.

 

[chess]

Very good point indeed!

I guess the previous guy hit the nail on the head somewhat - the environment gets hot and is certainly liable to water damage from leaking seals/joints although 6 years doesn't seem long at all.

But the manufacturing market is the same the world round: made to breakdown, not to last. Cynical I know but probably some truth in it.

 

[nickso]

it may be made cheaper now but there is still plenty of equipment from 1981 that doesnt work due its poor quality.

modern boilers have more in them to go wrong and they do, quite a lot. i suppose the same could be said for most things these days.


BTW i have 3 sinclair spectrums and none of them work, i think i could make a working one out of the three though

 

[Coniferman]

I read that the first batches of the Xbox 360 had about a 30 % chance of failing already and all will eventually fail. Microsoft were forced to extend the warrantee period. The reasons given were because of it overheating and the lead free solder failing. (and lack of experience with the lead free during manufacture)

I don't know if this is true and/or if it relates to boilers ????

 

[corgiman]

I still cannot understand that a good PC mother board will cost you about 50 quid but a PCB that looks like a kid with "Making PCB's for dummies" cost nearly 300???

 

[Corgigrouch]

Hmm.. I have a theory that is based on no fact whatsoever.. Especially regarding those boilers with £300 PCBs which will remain unnamed but would not be my Ideal choice... Many of these boilers are sold to builders for use in New build developments...Builders being the tightfisted gits that they are will only consider one thing..The bottom line and will regard the cheapest boiler as the best boiler... Boiler manufacturers are aware of this and so will (Perhaps) cut the price of a new boiler to a developer down to the bone.. Question is how does the manufacturer make a profit on the boiler....Idea!!! make the PCB so flimsy that it fails and if it fails out of warranty, then sell the customer a new PCB for a stupid price.. He needs it and has no alternative.

 

[nickso]

Hmm.. I have a theory that is based on no fact whatsoever.. Especially regarding those boilers with £300 PCBs which will remain unnamed but would not be my Ideal choice... Many of these boilers are sold to builders for use in New build developments...Builders being the tightfisted gits that they are will only consider one thing..The bottom line and will regard the cheapest boiler as the best boiler... Boiler manufacturers are aware of this and so will (Perhaps) cut the price of a new boiler to a developer down to the bone.. Question is how does the manufacturer make a profit on the boiler....Idea!!! make the PCB so flimsy that it fails and if it fails out of warranty, then sell the customer a new PCB for a stupid price.. He needs it and has no alternative.

thats a dangerous game to play with your brand name. i can see what you are saying but i doubt its true.

having said that plenty of brands dont seem to care much about their percieved quality.

 

[corgiman]

Well There is a combi out there that has a sort of tray thing that runs under all the parts of the boiler that will drip out a fair amount of water after it has been drained.

this tray has a fall on it from front to back leading to the front of the boiler, it then turns into a sort of funnel on to a lip that is directed over the PCB so that, if you are not careful to put down ALOT of tissue or remove the pcb, when the water runs it would drip straight onto the PCB.

Now IMHO this is not an accident and I have been caught for a new PCB after changing a pump so the Maker sells a 125 odd PCB due to the boilers design.

I would be Potty to name the manufacturer and I would question my performance to mention the boiler

However Baxi call it a 105



Is this a well thought out design or am I just a total cynic??

 

[Corgigrouch]

True that it might not be 100% accurate but it does sometimes appear to be the case, just call me Mr suspicious.. As has already been said, PC motherboards are far more involved than a simple boiler PCB and yet are a fraction of the price.. All boiler PCBs do pretty much the same thing but are so designed to be slightly different so that they are not interchangable and so you have to buy from the manufacturer.. As for not designing them to fail...

Take a look under the bonnet of your car and have a look at the air conditioning pipes.... Look closely at what they have used to clip the Aluminium pipes in place with...Mild steel clips? all in an area where a liberal spraying of salt water is likely and what does school boy physics tell us about dissimilar metals in an electrolyte? the design is either deliberate or the designer is totally incompetent. I'm just a suspicious guy

 

[Corgigrouch]

The manufacturers aren't interested in their brand name. They want sales of spares and market share

 

[gas4you]

Then after selling a cheap c r a p boiler refuse to do a fixed priced call out because you are too busy attending warranty calls

Oh and while your at it for those who take out the extended warranty, keep all callers who need help on hold for 30 mins

 

[ChrisR]

Spent some years in Electronic D & D, and covered QC and all that pretty thoroughly.
PCB's in pumas , and that generation, were mostly plain cheap, with obvious lack of effort for longevity. For a start the holes are/were too big for the legs of the components going into them, so you're relying on lots of solder, which is a pretty poor material for the job it's been given.

The boards in general seem to have got better, but relays are very marginal on ratings, designs are lacking obvious protection components, and on and on.

A boiler is NOT a harsh environment for a pcb. Having been given horrendous requirement specs for military applications, and got the reliability they require, sorting say a 10 year MTBF for a boiler board would be a breeze.

It would only cost a few pounds more to make a reliable pcb, but the retail price is always the same multiple for the company. Usually it's 10 - 15 times the marginal cost of the board. So your current Suprima board probably costs a tenner or so to make.

We're told that margins are tight on boilers, which makes sense. My feeling is that some manufacturers particularly, definitely aim to make a lot on parts, so they design-in fairly short life. OK, so be it. They're in business to make money, not marvellous products per se.

I'm sure they've done their work on finding which factors influence buying choice. WIth boiler designs changing every couple of years we really can't predict far ahead, so we're guessing. So things like the weight of the boiler become far more important to the installer and therefore the price, than whether the pcb is designed to last 5 or 10 years.

I had a guy working for me once who'd been at Frod in the days when the design-life of the car was 60k miles. A wheel bearing was reliably (statistically) lasting more like 90k, so of course, they wanted it fixed, ie cheaper, and matching the 60k spec. You wouldn't think it worth the change, but when you're making big numbers, it matters.

 

[Corgigrouch]

LOL every now and then a manufacturer shaves just a little too much off and catches a cold when too many parts fail whilst still in warranty...Statistically speaking they will allow for a margin of error but sometimes it just comes round and hits them hard where it hurts most

 

[Gasguru]

Here's the fan control part of a MicroGenus II board I came across today. The fan winding had shorted out blowing the 2 Amp fast blow fuses. Unfortunately the Triac bailed out with the current surge, clearly undersized to cope with this scenario.

It's an unusual design for non condensing boiler. Non UK versions can be set up with crude weather compensation. A 2 speed pump is fitted to the boiler and the fan speed is modulated to reduce excess air at lower heat loads. The optocoupler on the right fires the triac with the snubber components in the middle. Most manufacturers make do with a plain and simple relay.

Fortunately the fan and pcb together are about £160 which is a bargain compared to many other manufacturers.