More a point of interest than a query really.
I have recently had to fix my combi boiler - a Potterton Puma 80 - for a fault which has been very intermittent for the past 5 years but which has recently been occurring much more frequently and has got to the point when I can't rely on the boiler to light.
The problem was that the boiler would fire on demand but would sometimes stop after a time ranging from a few seconds to a few minutes. It would then fire up again, often remaining lit but sometimes repeating the same light-fail-light-fail sequence. Problem occurred whether demand was for hot water or central heating. Obvious causes such as water/system pressure switches, pilot thermocouple etc were all checked and OK.
Luckily however, during a particularly bad episode, I happened to notice the sound of a relay "chattering" with an accomanying flicker of the demand LED on the PCB (cover was off at the time). Wiggling the wires to one of the multi-connectors was found to make the problem go away (or return if the boiler was firing!).
Removing the PCB and inspecting the tracks proved to be something of a revelation. This particular problem proved to be caused by the fact that the connector pins are soldered directly through the PCB without any further mechanical support, so pushing home a connector puts pressure directly on the solder pad and consequently the PCB tracks themselves. In this instance the whole of the copper track had broken free of the board and had fractured. The sporadic nature of the fault was probably thermal in origin and linked to the expansion of the materials as the boiler fired.
In this case it was a simple job to create a wire bridge across the break. Aside from the obvious weakness of this construction, further examination of the PCB revealed 14 - yes FOURTEEN - solder joints which I would have been ashamed to have made myself. Some were incomplete and allowed movement of the component lead. Some looked like possible dry joints and had a very "crystalline" look. I resoldered all of these. Ten minutes work to solve a problem which had been bugging me for five years.
What I'm really trying to say is that, if you were faced with a similar issue, then it would be well worth having a good look at the PCB before consigning it to the bin. By putting right what the manufacturer couldn't be @r$ed doing in the first place might save you a couple of hundred quid.
I have recently had to fix my combi boiler - a Potterton Puma 80 - for a fault which has been very intermittent for the past 5 years but which has recently been occurring much more frequently and has got to the point when I can't rely on the boiler to light.
The problem was that the boiler would fire on demand but would sometimes stop after a time ranging from a few seconds to a few minutes. It would then fire up again, often remaining lit but sometimes repeating the same light-fail-light-fail sequence. Problem occurred whether demand was for hot water or central heating. Obvious causes such as water/system pressure switches, pilot thermocouple etc were all checked and OK.
Luckily however, during a particularly bad episode, I happened to notice the sound of a relay "chattering" with an accomanying flicker of the demand LED on the PCB (cover was off at the time). Wiggling the wires to one of the multi-connectors was found to make the problem go away (or return if the boiler was firing!).
Removing the PCB and inspecting the tracks proved to be something of a revelation. This particular problem proved to be caused by the fact that the connector pins are soldered directly through the PCB without any further mechanical support, so pushing home a connector puts pressure directly on the solder pad and consequently the PCB tracks themselves. In this instance the whole of the copper track had broken free of the board and had fractured. The sporadic nature of the fault was probably thermal in origin and linked to the expansion of the materials as the boiler fired.
In this case it was a simple job to create a wire bridge across the break. Aside from the obvious weakness of this construction, further examination of the PCB revealed 14 - yes FOURTEEN - solder joints which I would have been ashamed to have made myself. Some were incomplete and allowed movement of the component lead. Some looked like possible dry joints and had a very "crystalline" look. I resoldered all of these. Ten minutes work to solve a problem which had been bugging me for five years.
What I'm really trying to say is that, if you were faced with a similar issue, then it would be well worth having a good look at the PCB before consigning it to the bin. By putting right what the manufacturer couldn't be @r$ed doing in the first place might save you a couple of hundred quid.