I called our Rheem rep here and asked about it. If you had a model number he could plug it in and be able to tell. He did talk a recall back in the mid to late 80's that involved heat exchanger replacements that ran for quite a few years. The was also a lifetime guarantee on heat exchangers, in some models however, the heat exchangers are no longer being produced so they are offering money to the people affected. He also gave me beginning of some model numbers that should raise a red flag. For Rheem: RGEV, RGEA, RGED, RGKA & RGJA. For Ruud replace R with U. These heat exchangers are the cell type. For Rheem: RGEC, RGED, RGKB & RGKC. For Ruud substitute R for U. These are for the drum style heat exchanger. Long story short, there might be a problem but without a model numbers he has no way of knowing. Hope it helps a little.