purge motor keeps running


Old 02-05-03, 01:35 PM
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Unhappy purge motor keeps running

Hi All,
We have a Rheem Hi-efficiency drum gas burner. What has been happening lately is the purge motor comes on and runs&runs before the ignition fires up and the gas gets turned on. Normally it only runs about a minute or two.We typically have to turn the furnace power off, let it sit for 10 minutes or so, and turn it back on. The blower works ok when switched to fan. The intake and exhaust pipes are mounted horizontally, and sticking out the south side of the house. The reason I mention this is because a friend said there may be a problem with wind blowing into the intake, causing a problem with a sensor. Maybe the wind is blowing up my shorts! The last time the problem happened, the wind was blowing due north, straight at the pipes.
If that isn't it, what could be causing this intermittent problem?
I'm very technical and handy, so I can check some things out.
Has anyone seen this before?
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Old 02-05-03, 02:02 PM
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By purge motor you mean the combustion air fan motor? You're seeing this happen when the thermostat IS calling for heat? Or does it happen when the thermostat IS NOT calling for heat? Does the correlation between wind direction and the problem occurring seem to be consistent? How are the pipes terminated?
Old 02-05-03, 02:46 PM
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purge motor running

Hi, Thanks for the reply . When I said "purge motor", I did mean "cumbustion fan motor". This problem happens when the thermostat is normally calling for heat. I've only made this one correlation between wind direction and event. The wind has shifted since then from south to west & north. And we have not had this problem since then. But again, this is an intermittent problem. As for "termination" of the pipes, I'd say they are not terminated. The 2-3" dia. PVC pipes just stick out of the house, with nothing on the end. Hope this helps. Thanks..
Old 02-06-03, 02:57 AM
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Just to be sure we are on the same page, you're sure the pipes are 3"? Do they reduce to 2" before penetrating the wall? [from outside to inside] Do they stick straight out or do they go up about a foot or so then have an elbow that puts the pipe back on a horizantal plane? Look inside the intake pipe, there should be a wind deflector vane glued in there. Rheem makes piping termination kits for these furnaces. It sounds like the installer didn't use one. Can you post the model/serial numbers from the furnace nameplate?

Last edited by bigjohn; 02-06-03 at 04:55 AM.
Old 02-06-03, 03:07 PM
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Rheem purge motor info

Both intake/exhaust pipes start as 2" (I.d.) PVC, leave the furnace, then make a 90 parrallel with the ground, out thru the side of the house.There, the intake ends just about flush with the outside of the house. The exhaust changes to a 1.5"(I.D.) and extends another 2' past the house. It's still parallel with the ground. About 3' high.
I checked with a flashlight. Neither pipes have any divertor in it. I can see the 90 bend when I look down the intake.
The model is a Rheem Imperial Drum 90+, with hot surface ignitor.
The model # is RGED-07EMAGS. It's 75,000BTU.
We had a wind from due south today at 15mph, but not any problems..Hope this helps! Any suggestions?

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