Erratic Operation of Rheem Gas Furnace RGDD-06NC-ER

Old 01-11-11, 08:26 PM
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Erratic Operation of Rheem Gas Furnace RGDD-06NC-ER

For the past year the operation of this furnace has been erratic; short heat cycles, cold start-up sometime required repeated off then on reset of thermostat (to get furnace to run), the HSI ignitor would glow, pilot would light, burners would come-on approx 4 sec then quit. Most times the furnace worked properly, but seemed to stumble when room temperature dropped (like the middle of the night). The room temperature would always run lower than the thermostat setting.

I've been researching hot surface ignition furnaces on the internet & found this particular furnace uses the ceramic ignitor to both start the pilot, then is the flame sensor (safety device to keep gas on). Lot's of problems with this set-up.

I decided to adjust the ignitor forward so the tip was as far as possible into the burner. The ceramic block is slotted so I loosened the holder & carefully slid the ignitor forward. I was very careful not to touch or hit the pilot light manifold, also very careful not to touch the heating part of the ignitor (just handled the base).

I'm happy to say that the adjustment solved the erratic operation of the furnace. I guess the ignitor tip has more contact with the burner flame which results in more reliable temperature sensing. It stands to reason the problems would be more pronounced with colder air temperatures.

I did order a couple spare ignitors from Arnold's Service Company $26 each plus shipping. Their website was very helpful as was this forum (

Other tips I learned; work safe (turn-off power), keep the filter clean, keep the furnace clean.
Old 01-11-11, 08:47 PM
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Possibly the igniter was never in all the way. I thought most have screws that only allow one position. If you could slide it in and out it would be a nightmare for the manufacturer for recalls and warranty issues.

Mike NJ
Old 01-13-11, 07:19 AM
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Sounds like the flame sensor is dirty and/or burners are dirty.
Old 01-13-11, 07:43 AM
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I had a similar problem a year and a half ago shortly after having a new high efficiency Rheem furnace installed beneath the house in the crawlspace to replace the old one installed in a mechanical closet inside the house. Point is, that meant installing a new flue. Originally, we had a 2-1/2" diameter exhaust running fairly horizontally for about 6 feet. Changed the exhaust to a 4-inch pipe to reduce the back pressure and the furnace has not hiccuped since. Might be worth investigating in your case.

GC Builder/Remodeler

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