| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 889 Registered: 6-2009 |
Gentlemen, I know that a number of engineers haunt these environs, so I thought I'd ask about this here. All this spins off of a cranky gas water heater. The manufacturer is now insisting that the problem is not the main control box, but instead the pilot light assembly. Even more specifically, the tech rep said, "There's a diode in these things that tends to go bad." So, they've sent me a new pilot assembly, but I'm curious about the thermocouple portion. Entire Pilot Light Assembly - Pilot End  Electronic bit in thermocouple  Underside of electronic bit  Can anyone tell me what that electronic bit is and what purpose it serves? Also, what's the feeling about what the technical support person told me (even if the thing pictured is not a diode). Is it likely this electronic component has died in service on the existing pilot light assembly? Am I likely to have this failure again on the new one because there's a design flaw? Any insights appreciated. Brian | ||
| Randy Roberson Prolific User Username: wascator Post Number: 240 Registered: 5-2009 |
is it a pilot light, or one of the newer ignition units which generates a spark to ignite the burner? If so it might be a capacitor. Just guessing here... | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 890 Registered: 6-2009 |
Randy, It is a pilot light. There is a piezoelectric lighter for the pilot itself, you can see the red-orange lead and spark generator at the end of the ceramic fitting. Once the pilot's lit, though, it stays on and is what's used to fire up the burner. The thing I'm wondering about is definitely part of the thermocouple. Brian | ||
| Bob uk Unregistered guest Posted From: 94.197.122.91 |
The pilot light heats a thermocouple which produces millivolts the boiler controls shut down if the millivolts disappear The diode allows the millivolts to go to the control but blocks any volts going to the couple When the diode goes pop it goes open circuit and the boiler shuts down It is illegal to interfere with gas and in the UK prison So I am afraid you have to do as the gas man says and pay for a big New bit rather than a sixpenny diode (Message approved by david_gore) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 891 Registered: 6-2009 |
Bob, The water heater is under warranty so I already have the replacement pilot light assembly, which I took photos of. What you say makes perfect sense. I've just never seen a diode that looks like the circular disc on this thing. I'm wondering if the "can" is a heat reflector of some sort since this thing sits very close to the actual burner itself. You'd think this thing would have been much further away and nearer to the control box so that it didn't have to deal with the heat. Tomorrow will be the installation. Brian | ||
| Bob uk Unregistered guest Posted From: 94.197.122.88 |
I shall sleep soundly knowing that it is free I notice that this part has followed the bath tub curve of failure The New one will be trouble free for years then fail I am often asked mates etc about gas boilers and I just look and tell them to get a registered gas guy One of my uncle's worked for the London gas company and he used to check for leaks with a lighted match I remember him holding a match to a gas valve on a London gas cooker and showing me a small flame and then lapping in the taper using brasso followed by a tap with a hammer to seat the valve While a bread pudding cooked in the oven (Message approved by david_gore) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 892 Registered: 6-2009 |
Bob, Now I can sleep soundly since the new pilot assembly is installed and functioning as intended. Not having to worry about waking up without hot water to bathe with is far more conducive to sleep! Brian, who wonders how long it will take for the new pilot diode to fry (there is no change in design at all) - I hope the original problem was one of those "1 in every 10000 units" affairs | ||
| Bob uk Unregistered guest Posted From: 94.197.122.73 |
A gas fitter told me that a problem he has seen is the boiler is running constantly because the house owner is running at 30 deg with windows open for fresh air The control bits get cooked (Message approved by david_gore) |
