Rheem Furnace Problem (Condensate)

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I have a 12 year old 90% efficient furnace built by Rheem for Nordyne. It is a "drum-type" furnace (identified by a round "port" with bolts on the front of the furnace and a small viewing window into the combustion chamber. Don't know if your furnace is drum-type or not, but perhaps my observations will help.

I am having similar intermittant run problems and here is what I found. There are two drain hoses (one from the vent stack and one from the secondary heat exchanger) that empty water into a condendate trap (small plastic canister). These were originally latex tubing, which recently gave out. I replaced the tubing with clear poly-vinyl. My problem is that the inducer blower (exhaust fan) comes on, then the main burner ignites, the system runs for about 5 minutes, then clicks and shuts off the gas. A couple of minutes later the whole process starts over again. It takes 5-6 of these cycles to warm the hose up in the morning. What I found was that water is collecting in the tube from the secondary heat exchanger. Once it rises to the point that it backs up onto the heat exchanger, it blocks air flow in a smaller hose that goes to the pressure switch (a small round piece with two smaller hoses going to it). This action cuts off the gas at the valve.

On a couple of occasions the burner failed to light at all and the inducer fan just runs continuously. I found that a drop or two of water had gotten into the small hose coming out of the secondary heat exchanger to the pressure switch and would not let the gas valve open. Pulling this hose off and blowing through it usually temporarily solves this problem. However, I have not yet been able to find a solution to my overall condensate problem yet.

I have also found that in extremely cold weather my air intake pipe sometimes "frosts over" at the inlet, does not let enough air into the combustion chamber, and the burner will not light then either. In this case, the inducer blower cycles on, then the gas valve clicks on and then right back off, the blower fan comes on for a couple of minutes and then the whole thing shuts down. It then starts all over again in a few minutes.

Hope this helps. Godd luck.