Gas Pilot Sensor

"R-Guy" wrote

Not sure, but they describe a kit that detects 'blown-out' and also produces sparks to relight the pilot at web page

so I assume you could get one of those and build something like you want from the detector front-end part.

I know it's a pain to build a project using standard thermocouples because they give you like 30 millivolts, tops, so you need really really big metal {and tightly connected} fittings to avoid high resistance. But that same web site describes a somewhat rare 'Millivolt Thermo-pile' thermocouple,

whoah, it turns out my house uses one in this ancient {circa 1970's?} in-wall gas furnace, so I slapped a vom on it and it puts out a full 300 millivolts under load! This voltage is high enough that it has just a regular pair of wires dangling out the end, and spade terminals on those wires, instead of a screw-on coaxial design. If you can find a source for that part, you should be able to design or hire a repairman {or ham radio operator} to design an interface circuit.

We call that "bassifying" a solution. It'll involve about fifteen relays and a Napco LCD keypad programmed to read "Attention Burglar. Go ahead, make my day."

sounds a little 'fishy' ;)

"Frank Olson" wrote

If you've got external power available for this project, there's no real reason to prefer a thermocouple anyway; just mount some metal in the pilot frame, and attach a thermal switch on that metal, far enough back from the flame that you don't burn up said switch. Problem; does it false-trigger when the room is too cold?

That solution won't work. When the pilot lights the main gas jets, you're liable to melt any "thermal switch" in the vicinity. Anyone thought of using a flame detector? It will be "in alarm" for the whole time the pilot's lit, so you'll have to wire your outputs a little differently from the "normal" to achieve an "alarm" when the pilot "snuffs". On the other hand, you could use a combination of sensors to achieve the same purpose. A temperature sensor that will "alarm" when the room temp falls below a certain point (which will happen if the pilot "snuffs") and a natural gas sensor which will alarm in the event the thermocouple fails to shut down the gas to the pilot light. Granted, this won't provide an "instant" alarm as a flame detector will, but it wil provide sufficient warning to the homeowner before there's a risk of freezing.

"FIRETEK" wrote

Hmm, the area below the burners seems fairly cool in the gas appliances I've seen. I was thinking of a fairly long metal probe, but yes, this would take some trial-and-error...

I've seen many "do-it-yourself" type solutions to everyday "problems". Invariably they are both illegal (code wise) and unsafe. Stick with the proper technology when it comes to furnace and fire/flame sensors. A "Mickey Bass" solution may sound good but may also leave your ass hangin' out a country mile.

if unit does not already have code required system bilt in to shut unit and supply off whn this happens, you shld get tech to determine who sold you this thing.

many units have contacts or circuit that provides spark initiator or other to re-light pilots whenever this happens.

reverse/down draft from stack should not affect pilot, if it is, u have stack problems!

get a tech manual on the controller first

& dont screw with your house/family's safety.

I don't have a problem with the gas not shutting off. I don't want anything to re-light the pilot automatically. I don't have a stack problem. I am not screwing with anyone's safety.

We sometimes get severe wind storms here and I am simply looking for a way to know if the pilot gets blown out.