TimB Posted February 26, 2013 Share Posted February 26, 2013 Just about every gas fired furnace nowdays has a flame rod, and as an HVAC/R tech, I've seen many, but lately I been having trouble with a batch of them I got in. The flame rod is nothing more than a metal rod, insulated from ground by a ceramic insulator that also mounts the flame rod, and holds it in the flame of the gas burner. The flame transmits an electric current that the rod picks up and transmits through a wire, back to the ignition module. This is how we prove flame on these such appliances. Anyways, the flame rod is designed to contact the flame, and frequently glows red the entire time the burner is burning. Seldome do we have a problem with these burning in half, or melting, warping, or crystalizing, but on this latest batch, I seem to be having all the above happen. A flame rod that I had installed 2 weeks ago, now has a "plumage" running the 3" of its length. It looks like a bloom, or a small pile of fileings atop a magnetic point on the side of the flame rod. This track can run the length of the rod. My question is, would this be evidence of impurities in the rod, or of improper flame properties, like too little air (May cause a carburizing flame). I don't see any problems with my equipment but I would like to better understand what the rod is telling me. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 26, 2013 Share Posted February 26, 2013 Just about every gas fired furnace nowdays has a flame rod, and as an HVAC/R tech, I've seen many, but lately I been having trouble with a batch of them I got in. The flame rod is nothing more than a metal rod, insulated from ground by a ceramic insulator that also mounts the flame rod, and holds it in the flame of the gas burner. The flame transmits an electric current that the rod picks up and transmits through a wire, back to the ignition module. This is how we prove flame on these such appliances. I want to hear how you get flame to transmit electric current. I always thought that the electricity was sent from the module to the probe, and the heat of the flame made the a conductive connection from that heating that allowed it to returm to the module, proving the flame exists. Quote Link to comment Share on other sites More sharing options...
doc Posted February 27, 2013 Share Posted February 27, 2013 This last batch of rods didn't happen to have been made in China did they? Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted February 27, 2013 Share Posted February 27, 2013 Wot did the makers of the rods say? Quote Link to comment Share on other sites More sharing options...
ciladog Posted February 27, 2013 Share Posted February 27, 2013 You may want to check this BBS. It has a fairly good explaination. http://hvac-talk.com/vbb/archive/index.php/t-96637.html Quote Link to comment Share on other sites More sharing options...
SmoothBore Posted February 27, 2013 Share Posted February 27, 2013 I want to hear how you get flame to transmit electric current. I always thought that the electricity was sent from the module to the probe, and the heat of the flame made the a conductive connection from that heating that allowed it to returm to the module, proving the flame exists. It's been a few DECADES since I used Flame Rods in the Gas burners on Die Casting Machines, ... but if memory serves ..... On the Burners that I've had experience with, the tip of the Flame Rod, was only used to sense the Pilot Flame, ... and never came in contact with the "Main" flame. The Burner Control charges the Flame Rod with a minute "AC" current. A "blue" flame will, ... through the process of Ionization, ... conduct Electrons through the "blue" Pilot Flame, ... to Ground. The Burner Controler senses this tiny current, and will then allow the Temperature Controller to open the Gas Valve, that supplies the "Main" flame. . Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 28, 2013 Share Posted February 28, 2013 It's been a few DECADES since I used Flame Rods in the Gas burners on Die Casting Machines, ... but if memory serves ..... On the Burners that I've had experience with, the tip of the Flame Rod, was only used to sense the Pilot Flame, ... and never came in contact with the "Main" flame. The Burner Control charges the Flame Rod with a minute "AC" current. A "blue" flame will, ... through the process of Ionization, ... conduct Electrons through the "blue" Pilot Flame, ... to Ground. The Burner Controler senses this tiny current, and will then allow the Temperature Controller to open the Gas Valve, that supplies the "Main" flame. . cool thanks, there are not a lot times that I have to address plasma or Ion issues as an electrician, now I gotta read up on that Quote Link to comment Share on other sites More sharing options...
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