Need more info!
Secondary heat exchanger is likely plugged.
you need to provide some intelligible data on this. What were the combustion analysis numbers and what is the appliance doing or not doing? How did you come to this conclusion? By *rich* what do you mean?
Craig1 is probably correct, but you need a flue gas analysis. You needto know how much co is in the exhaust.
The usual amount is 'higher PPM than my TPI is capable of reading'.
If what I think you’re talking about is true I would also suspect a clogged secondary. I encountered many carriers with clogged secondary’s and the symptoms were always the same, awful smell at exhaust, extremely high ppm on my combustion analyzer.
OK relax, here is some data. Found 4 inch filter very plugged (removed), supply temp. at 100 degrees, return temp. 70 degrees, factory spec is 40-70 delta T. Found gas manifold pressure at 3.5 inch water column. Took CO reading in house and readings were 0. Did not take readings out at exhaust. (Stupid) Did notice pressure tape fitting on gas valve on manifold side connected to combustion fresh air intake.
Thanks for the help!! Will return and take CO readings on exhaust and let you all know the results!!
Does the exhaust have a bad smell? Or what led you to believe it was rich?
Customer was complaining, and when I arrived I could smell it. Then I went over to the exhaust and it just smelled rich to me. Hope that helps.
Just took CO readings and it was off the scale, so i am a commercial HVAC guy, can you give me an idea how hard it is to change out a secondary heat exchanger and time involved?? (Still waiting to hear back from Carrier about warranty details)
I wouldn't bother replacing the secondary, they changed there design because it was so problematic. Last one I found with bad secondary they gave like 500 or 1500 towards a new furnace I think.
That one smelled terrible on lp.