Johnny B Good laid this down on his screen :
No it didn't - during test the LED survived for a couple of days, since I reduced the cap value to the ones I suggested, the entire set of LED's have so far survived a couple of years in circuit with zero failures.
I used so far as possible the components I had to hand, with only a rough idea of the LED spec..
JoeJoe used his keyboard to write :
I cannot remember what level sensing system they used, but as an engineer, I would quite often come across similar automatic condensate pumps in a/c systems, where the sensing systems would become choked with dirt. The usual fix was to replace them with a peristaltic condensate pump, which used a pair of temperature sensors, one in the ambient air, the second one in the output of the a/c unit. As soon as the cool sensor detected cool air from the a/c, the pump would be triggered to run.
The point I am trying to make, is that I would ever just replace any item, without examining the failed item to work out in what way it has failed - even if that involves destroying the item and a thorough bench test. It might be as simple a fix as cleaning out the collection tray and the sensors.
Andy Burns has brought this to us :
That is what I would expect - call for the boiler to run, will be via the pumps 'safety circuit', which confirms that the condensate pump is not flooded and working normally.
Bridging that connection across the pump, should enable the boiler to run when called.
Under the floor is probably one of the worse places for bacterial slime to occur and build up, could you not find somewhere more accessible for it to be installed?
If you do have it replaced, ask for the old unit and bench test it after cleaning it out - bet it works perfectly.
Could it be they have wired the pump in such a way that it can inhibit the boiler (by removing power) should it fail in some way? There is a certain "fail safe" logic that would stop a potentially damaging condensate related leak.
To be fair, I was only guessing that LEDs would have a lower average to peak ratio current handling spec based on the larger forward volt drop compared to an ordinary silicon rectifier diode. I may have under- estimated their peak current handling abilities using 'faulty logic' - I've never checked LED data sheets like I've checked out rectifier diode data sheets.
It's good that you at least considered the potential risk of switch on transients and added a surge limiting resistor even though, to my mind,
220 ohms seems a little on the low side to guarantee safe operation in a worst case scenario. However, given a low enough C value, the virtue of 220 ohms versus 10K (or even 2K2) ohms is that it makes the switch on transient mercifully brief.With the use of "Super Bright" LEDs and a starting point of 470nF, I'd have thought the motivation to try a 100nF cap would have been to reduce the blinding glare rather than to stop them burning out. :-) Indeed, if you'd decided to use those new funky blue LEDs, you'd have landed up using 4.7nF caps for the same reason.
BTW, where I'd misremembered fitting a single gang "Protected Supply" socket, it turns out that all three sockets I'd modified with indicator LEDs were dual gang. Only one is now still in use in my office come workshop. The other two are no longer serving IT kit so that gave me a chance to check them out to verify the C and R values I'd actually used in my LED indicator lamp circuit.
I've only been able to look at one of the two unused sockets so far and the values used here (100nF and 2K2 ohms) aren't quite as I remembered them but this socket may not be typical of the other two which may well be using 47nF caps instead.
Even the surge limiting resistors might well prove to be different as well - all three socket mods would have effectively been 'prototypes' so no guarantee of 'consistency' (at least as far as the C values used). The R values would probably have all been 2K2 but even here there may have been some experimentation so 10K is still a possible maximum value.
Without undoing the other two sockets to examine the indicator lamp components actually fitted, I can only speak for the one I've examined so far and I'm not going to assume that I used the exact same component values in all three cases (other than for the actual 1970s vintage 3mm red LEDs themselves).
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