Problems with Rheem RGPL in dual fuel setup


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Old 01-03-09, 01:29 PM
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Problems with Rheem RGPL in dual fuel setup

Here's my system: Rheem 2-stage gas furnace (RGPL-07EBQR) with Ruud HP and a Honeywell 8321. Installed about 3 years ago. Itís set up at the stat as 3-stage heat, 2-stage cool; but I believe that the 2 gas stages are jumpered together so that the IFC at the air handler picks which runs.

Here's what it started doing last night: when the system comes on calling for heating, the compressor starts up outside, and the air handler fan starts. The system doesn't really run long enough to heat things up, maybe a couple of minutes. I can hear the relays click in the thermostat (sounds like 3 total), and the backlight flashes for a moment. Then the "Wait" indicator comes on, and the compressor shuts down. It waits until the stat's compressor timer expires, then does the same thing again.

I tried several things today (a bit scattershot as I tried to figure out and get parts before the one local supply shop that was open on Sat closed at 1PM). I replaced the 24VAC transformer, although it may have just been a burned out fuse. I also grabbed another thermostat, but programming that identically led to the same operation.

Hereís where things stand now: Both the power and status LEDs on the IFC control board are lit. With the thermostat in test mode: the fan will not run (Test 2), the compressor will run, but not the fan (Test 3, options 1 and 2); for Test 3, option 3, which should run all 3 stages, I get the repeated 3 relay clicks and a backlight flash.

Iím looking for suggestions for how to tell whether the furnace board is bad, or if thereís something else going on that I should check.

Thanks. I'm undecided about whether to DIY this or call a pro come Monday AM, but I'd like to know what's going on. I have been learning more about how it's wired up, b/c I wanted to run the HP lockout from the stat instead of the fossil fuel kit at the HP. But I literally hadn't touched a thing before it went on the fritz.
 
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Old 01-04-09, 01:50 PM
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I've looked at this a little more today. When I set the fan to run at the stat, I can measure voltage across the G and common terminals at the furnace. But the fan doesn't run.

It's a variable-speed fan with many wires back to the furnace control card. Any suggestions on how to tell if it's the card or the fan itself that's having problems?

Thanks!
 
 

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